Post by Ron Walker on Apr 16, 2022 11:52:20 GMT -7
Posted by: Ron Walker Dec 13 2006, 02:20 PM
Just a quick news flash.
Aaron Phillips just sent me a "HomeStar" planetarium projector for review.
He is the owner of "The Karakuri Corner" which imports a lot of nifty "toys". He is the distributor of the two other planetarium "pin-hole" projectors reviewed on these pages. I look forward to reviewing this unit because it is optical "lens" projection rather then "pin-hole" and should be very interesting as to the quality of sky.
More to follow.
Check out the various "goodies" at Aaron's site.
www.karakuricorner.com
Posted by: mrgare5050 Dec 14 2006, 01:54 PM
OMG! i have been wondering what the homestar does for soooo long. the thought comes then, what if you combined it with one of those mirrors yall have been talking bout (thats tennessee talk)...
gare
Posted by: Ron Walker Dec 18 2006, 04:13 PM
This is not the full review, it will follow. All I can say is BUY ONE NOW!!!!.
Yes, it's expensive. $240 for a toy planetarium. Outrages you say at first, but the image this "toy" puts out is truly outstanding!
Just a bit of how it works and then a couple of pictures to wet your appetite. If your not planning on spending really big bucks or spending untold hours building (and even if you are) this little machine is for you.
First I can tell you this machine is basically a small slide projector. It makes use of an excellent wide angle lens to project its star field on any flat surface. I plan to make some further experiments with projection into a dome and into a dome mirror, but they will follow later.
The image projected can be most apply compared to a rotating star chart. We all have one of these. Dial it to and day and time and it will show you (on a flat two dimensional plane) what stars are up for an average mid Northern latitude.
This projector is set up for Japan and will work very well for all of us.
Now I'm planing one of my typical reviews as time goes on but it will take a bit of time to prepare so I just wanted to give you all a heads up as to my first impression of this thing.
My "media room" is the largest in my house and has a cathedral celling 12 feet above the floor at the peak. There are large beams that are placed six feet apart that span the distance from the peak beam to the room walls. Between these beams is a white ceiling. From the floor, this little device projects a sky approximately 18 feet in diameter.
Now my first experience with this "toy" was nothing short of jaw dropping. An internal motor rotates the sky around in six or so minutes and I found myself laying on the floor looking up at this rather beautiful sky. The impression being that the white sections of ceiling between the beams were actually glass panels and I was looking up through them at a most spectacular sky!
I must have been laying there for a while, finding constellations, for my wife came in wondering where I was and what I was doing. Upon looking up all she could say way "wow" and then joined me on the floor looking up. I pointed out stars and constellations to the best of my ability and we must have been there the better part of an hour before reluctantly going to bed.
I have taken a few pictures to try and convey to you how "spectacularly" this projector works. The only comparison are the two projector kits I have put together and I will show you their output.
I do want you to know, however, that if you would like a small planetarium that probably looks better then anything available commercially for under a couple of grand, and you don't plan on building a dome to project in, this little unit fills the bill.
The following picture is a look up from my floor looking at the projection on my ceiling as described above.
imageshack.us
Posted by: Ron Walker Dec 18 2006, 04:36 PM
This picture does no justice to this projector. My first image was a ten second exposure with a very rough focus. The unit in reality projects extremely sharp star-fields.
Again the original star-field.
imageshack.us
As a comparison I placed the two other planetarium kits at the same location and took pictures of their projections. They were much dimmer so these photos are 30 sec time exposures.
First the $30 planetarium kit:
imageshack.us
The star images are a bit elongated because in a pin hole projector one is basically just projecting an image of the bulb filament up on the screen. It is easy however to make out the constellations. Again, a good basic teaching tool.
The $50 planetarium kit:
imageshack.us
While there are many more stars, the constellations are much harder to find, and the size of the first magnitude stars is almost laughable.
I went back to this new projector and did a 30 sec exposure as well for a true comparison.
imageshack.us
Constellations easy to find, even Cassiopeia in the Milky Way. I could fall asleep under the stars every night! No problem, there is a self timer to turn it off. But how long will the bulb last, no problem as it's an LED. Remember a true optical lens projection planetarium does not rely on a small filament for pin point stars.
There will be more to come about this truly unique unit.
Posted by: Ron Walker Jan 6 2007, 03:13 PM
OK, a little more about this projector. First it is an optical unit. That is unlike most small planetarium projectors that use "pin-hole" or simple light and shadow projection, this unit uses an actual lens to project the slide of the star field. Designed by the same fellow who designed the "MegaStar" professional projector, this unit only uses one lens for the entire hemisphere, while the big brother uses 18. This is also true of the Zeiss and Goto larger projector and is why their star fields look so good. It is also why this unit costs as much as it does. However, I would rate its cost as a bargain.
imageshack.us
This first picture shows the unit with projection lens pointing up. The lens is surrounded by a large "focus" ring which allows focus from just a few inches to probably infinity. Please note a second smaller projector to the right of the main one. This is also an optical projector and projects a meteor "shooting star" about every thirty seconds or so. This projector is motor driven by the same drive that rotates the sky "diurnal motion" of the sky which runs a day in about ten minutes or so. The meteor is always in the same location with respect to the projection surface which gets old, but since the sky is constantly changing most would not notice unless observing for some time.
imageshack.us
The slide that is projected is circular and beautifully made. The black around the stars is extremely black thus projecting a most beautiful star field. It is round so that when inserted into the projector the star plate can be easily rotated by the motor mechanism within the unit.
imageshack.us
The star plate is inserted into the slide carrier and slid into the center of the projector just above the operational controls. Two slides are included. One of the sky as seen from Japan (works fine for most of North America) and a second one with constellation outlines (the connect the dot kind). It is my understanding that a disc for the Southern Hemisphere is also available for an additional price.
Posted by: Richard B. Drumm Jan 6 2007, 03:30 PM
I like it! Especially the Milky Way image!
Verrrrry Nice!!!
Now all we need is a cheapo, easy-to-setup dome...
Rich
Posted by: Ron Walker Jan 6 2007, 03:45 PM
The projector is powered by 5 volts DC from either a "wall wort" or a small battery case. Instructions are all in Japanese and thus useless to me as well as an audio CD which has a bunch of high school students talking in Japanese about the night sky (I guess). The controls on the projector are straight forward and in English.
imageshack.us
From right to left they are; POWER (turns the unit on and off); SS (Shooting Star-Turns the lamp on and off for the shooting star projector); MOVE (turns on the motor to move the star plate and SS projector motion. This is labeled N and S but I think it should be labeled E and W.; TIMER (there are three times 15, 30, 60 minutes which will automatically turn the projector off after the indicated time periods so you can fall asleep under the stars.
As I mentioned before, the light source is a very bright LED with a daylight color temperature, giving the stars a very realistic "cold" blue look. The SS projector has its own LED thus it should be a long time before you ever need to change a lamp!
A small DC electric motor drives a gear train that supplies rotational power to a rubber roller which is in contact with the outside edge of the star plate, rotating it around in about 10 minutes or so. There is also a small rubber belt which delivers power to the SS projector. If anything would "die" in this projector it would be this, but it appears very well built and should last a long time.
I have shown you how this projector looks reproducing the sky on a ceiling and I think all of you would be very pleased with its performance. For those of us "really" into planetariums, the question of how it would work projecting into a dome or hemispherical mirror comes up.
Posted by: Ron Walker Jan 6 2007, 04:36 PM
Rich you are so right.
I have been putting together an experimental dome approximately four feet in diameter to make as many mistakes as possible before attempting the construction of the large one. It is far enough along to use in this experiment. The trials and tribulations of dome construction can be found elsewhere on this forum.
As I have said, this projector projects a beautiful reproduction of the night sky and as Rich has commented on, the Milky Way is outstanding. Projected onto a flat wall or ceiling the reproduction is much like a flat star chart (wheel). The question is how well would the sky look projected into a dome. The answer in a word is "spectacular".
I have not mentioned this before, but the system is designed in such a way as to accurately rotate the sky around the pole star. In order to fill the entire four foot dome, the projector needed to be placed about two feet below the spring line (horizon).
imageshack.us
Here is a view looking directly up into the dome. The wood circle at the top is part of the support structure of the dome and will be covered by a circular white plate. You can, I believe, get a fairly good idea of how good this looks. You can easily find the big dipper pointing to the north star with the Milky Way high overhead as in summer. I did not have a wide enough lens to get the entire width of the dome in the shot, but let me assure you this look fantastic.
imageshack.us
Looking from the side across the dome, you can see the dark "spring line" support at the top. The stars remain sharp and fairly round even at the edge of the dome.
imageshack.us
Another view at a different time of year/night from the side.
If I ran a small or large museum/planetarium and had an exhibit about the Milky Way, this set up would be in the center of the room!
The final experiment was projecting this unit into a dome mirror. First a shot of the ceiling with the projector projecting directly up. The image is approximately 12 feet away and the entire sky is approximately 18 feet in diameter.
imageshack.us
Again, the feeling that I was looking through glass panels between the beams.
imageshack.us
Now the image not only fills the entire width of the room, 30 feet, but also projects down the walls to the floor. This shot is of the same area as the picture before and you can see the real negative to this type of set up. The larger the angle on the dome mirror to the projector, the larger and more elongated the star images become. This is, however, not how this type of projection would be used, as a computer would be required to "correct" for the distortion. I have reservations about this type of projection and am coming to the conclusion that it should be used for "special effects" only. The main star field should be projected by a good old optical projector, or if you must have video projection, use a system that uses an extreme wide angle "fisheye" lens.
Anyway, as to the "HomeStar" projector. Buy it! If you are at all into planetaria but don't want the expense and hassle of construction, you would be hard pressed to find a better introduction into the indoor night sky.
Posted by: Launch Vehicle Jan 8 2007, 12:48 PM
Ron, I have a 100" fabric dome. Based on your observations - and depending on how it's positioned - what percentage of its inner surface might be covered by Homestar's field without noticeable distortion or bloating of the stars? Also, how dark is the background sky? Any light leaks? At your projection radius, approximately how big was Sirius? Thanks!!! -Bob
Posted by: Ron Walker Jan 8 2007, 03:08 PM
Hi Bob,
My experimental dome is about 48" in diameter and the projector needed to be about two feet below the spring line for it to fill the entire dome. At twelve feet the projector would project an image approximately 18 feet in diameter. I would guess that you could fill your entire 100" dome with the projector placed 4 to 5 feet below the spring line. This will fill the dome all the way down to the horizon.
There is a slight elongation of the stars (as one would suspect) as they approach the horizon but this is slight and not bothersome to my eye. Now I am a bit of a perfectionist so I would think most would be very happy with this unit. As it is an optical lens-ed projector the stars are projected as very small and fine dots.
The designer has ( in most of his projectors) made the brightest stars overly large, but not anywhere as big as in his other "pin hole" projectors. I'm guessing Sirius would be about 1/2" in diameter on your dome. If I were making it, I think I would have made the first magnitude stars a bit smaller, but the other aspects of this machine (especially the Milky Way) are so outstanding that you will soon overlook the shortcomings.
Since it is optically projecting a "kodalith" type "slide" the background is jet black, as good as any optical projector of this type. Looks like a Zeiss sky background. Black as pitch, you will not be disappointed. Also the projector is designed extremely well so there are no light leaks either up at the screen or down towards the floor. When working in a dark room it is actually hard to see the projector.
If there is any drawback at all it is that the projection disk is designed for the latitude of Tokyo, Japan and can not be adjusted from that point without leaving some of the dome without stars. Since this is about mid America the unit is very useful as a "home" teaching tool.
While it is not perfect by any means, for $240 you would be hard pressed to find or make anything near this good.
Posted by: Launch Vehicle Jan 9 2007, 07:24 AM
Thanks, Ron. I think many of us could live with a 1/2" Sirius. It would be interesting to see if those stars near the horizon could be sharpened with some sort of overlay corrector lens. Anyway, who says a dome must be completely hemispherical? Some of those flattened ceiling "half domes" (used to enhance the placement of high-end chandeliers) might be just the ticket in a dual-duty family room. Perhaps this could be combined with your evolving dome setup -- by blotting out all the stars outside the galactic plane, and carefully "registering" what is left, Homestar might serve as the ultimate full sky Milky Way projector. One final question, the constellations outside the galactic plane were easy to make out in your photos. Were they more difficult to trace inside the Milky Way?
Posted by: Ron Walker Jan 9 2007, 10:58 AM
Hi Bob,
The beauty of this hobby is in the experimentation. If you are happy with a dome starting at 45* up, go for it. I was very happy with it on a flat ceiling just because it was so spectacular. I was more impressed in the full dome (even though it was small at 4 ft.) because it just looked more like the sky outside as to where the stars were in relation to my viewing perspective.
A corrector lens might work, but I kind of doubt there would be a stock one. The cost of manufacturer would be so high as to make the answer moot. If they made star plates for the entire sky (like the plates on the Chronos) I would be tempted to get 32 of these machines and make a true optical star projector! I would probably black out the first magnitude stars and add separate brighter projectors for them but all this is wishful thinking.
As for the constellations in the Milky Way itself. The pictures I took both in the dome and of the ceiling do not do the image justice when compared to the naked eye. I can very easily see Cassiopeia and Cygnus the swan as well as Lira the harp. It is like the first time seeing a Zeiss sky. After you start breathing again and start looking around, the constellations become visible amid the 10K stars.
While the last thing I need right now is another planetarium projector, I'm thinking of getting one of these just for the way it projects the Milky Way. More for a separate exhibit with the four foot dome about the Milky Way. If I could incorporate it into my evolving machine then there would be no question, I'd buy it yesterday, but it is designed to be the entire sky from one latitude and would not work properly when one moved to different locations on the Earth.
With other slides It could be turned into a special effects projector as well since it has such a wide angle lens. Might be worth the cost just for the lens. Decisions, decisions....
As to star sizes again, the stars projected on my ceiling are about twice the size in diameter as you would expect in your dome if you filled the entire thing. Do to the time exposure and not perfect focus they are, if anything, larger in diameter then they truly are. To get an idea of size, the bottom of the large beam is six inches and the small beams are four inches. Only the first magnitude stars approach 1/2 inch in diameter so they would be less then 1/4 inch on your dome. However, remember, the stars are closer to you so they would appear very much the same size no matter how far you projected them away.
No planetarium projector is perfect and this one sure isn't. Remember the original Zeiss Mark II projected Sirius two inched in diameter. True it was a 68 foot dome, but that star sure looked like a circle. They soon added separate projectors for all the first magnitude stars and all was well. Again remember this is only a $240 projector, and in my very humble opinion, well worth it. If you don't like this, start saving your money, because the next stop is "The Twilight Zone", and were probably talking six figures.
Posted by: Launch Vehicle Jan 9 2007, 01:45 PM
Ron, wouldn't it be interesting if someone were to do a long exposure of a dark sky (or Zeiss-projected full dome of stars) with a 180 degree fisheye lens, then adapt the resulting transparency to fit Homestar? Of course, this would be done at your local latitude. Better yet, how about some high resolution slides of the moon and planets? Center the nucleus of the Whirlpool Galaxy and watch it spin!
Posted by: Ron Walker Jan 9 2007, 11:18 PM
How right you are Bob. I'm thinking it would probably be fairly easy to make an adaptor for 35mm slides and use them in this projector. That way you could get some pictures (even ones you take yourself) of different objects to use in this machine. 2X2 inch super slides would be great! Not sure about using a "fish eye" lens to take an image but it sure would be a great experiment. The spinning Galaxy would indeed work extremely well.
I'm thinking of some experiments with "ink jet" transparency film and some of the things you could make with that. I'm all ready planning on doing some "constellation outline" figures for my main projector once I fine some good drawings.
My work schedule has gotten a bit heavy this month and there just aren't enough hours in a day to do all the things I want to do. :roll:
Posted by: Ron Walker Jan 9 2007, 11:22 PM
Also I should point out the this projector is set up in such a way as many stars (and constellations) do set and then rise later as the day/year progresses. There not all up there all the time. Just the circumpolar stars at the Tokyo latitude.
Posted by: mrgare5050 Jan 10 2007, 06:35 AM
wanted to get my 2 cents in on this interesting discussion, but dang it, im still smarting from not having 300 bucks to outbid a space toy collector on steve pielocks spare renwalls cosmorama, now here's another expensive yet intriguing 'more than a toy' projector, and this one we've all been looking at and wondering about for a long time!
first of all, its got a meteor projector! that alone makes it cool, use it once a show if nothing else. its small ... small projectors can be moved.. swirled.. as you say ron, and as we said with the smaller kodalith unit, all kinds of interesting special effects come to mind. maybe it could be rotated and then condensed outer to inner like youre being sucked down a wormhole, to the sound of 2001 a space odyssey. stuff like that!
if i had one i'd do the blink test. set it up next to my regular projector and look at one sky, then lights out, then the other .. what would my first impression be? its the old argument, should a sky be real or should a sky fire the imagination by being just a little beyond .. oddly, one of my best memories of the adler shows i attended was the one where the guy showed the dull sky we were all used to in chicago, even in the 60's, the one where i poked around with my 2.4 inch and filled notebooks of excited entries. THEN he turned up the stars .
over the years ive sortof more gotten used to fighting to see them, sometimes my perfect planetarium sky gets boring.. no clouds to see them poking out of .. no dwindling light cones over cities as we head to the country .. no moon .. airplanes .. somehow this quest for a perfect sky sometimes loses the charm .. the too many star worries that at times i feel like im the only one who shares .
anyway just some thoughts on this remarkable projector! gare
Posted by: Launch Vehicle Jan 10 2007, 10:33 AM
Gare, exaggerations are what make planetariums "work". Remember Zeiss' one (2? 3?) minute Moon? -Bob
Posted by: Ron Walker Jan 10 2007, 01:01 PM
Gare,
The seeing conditions as they look from Chicago is exactly the reason that you need to be able to show a full sky. You can start (as they did at the Adler) with only a view of a couple of hundred stars (or even fewer as I've seen from some cities) and then talk about the effects of light pollution or the real reason the ancients saw creatures in the sky and we can't. Because they could see stars that we can't.
I remember the Adler shows where they would take the down to the Chicago level of light pollution and talk a little about finding your way around the night sky. You could see the Big Dipper but not all of the Little Dipper. The the lecturer would use the big Zeiss as a time machine and say he was going to take us straight up three miles above all the smoke, haze, and light pollution and "see the true beauty of the night sky". There would be that great "gasp" from the audience that any previous attendee would know was coming.
The sad fact is that a full and spectacular Zeiss night sky is not an exaggeration but an accurate depiction of what we should see an a clear moonless night.
I, for one, will know that I have made a projection display worthy of sharing when I get my first (gasp -Oh My [Wow]) from any member of the audience. Some might look down on that as a "bad teaching attitude" or "ego showing" or whatever, but (being a bit of a showman) that's what will make me feel good about doing and sharing this fascinating hobby.
Posted by: Ron Walker Jan 10 2007, 01:07 PM
Another thought. Remember that you can always do an introduction to the night sky and constellations with the star intensity down a bit and the twilight light not totally off. This way you can get your audience adapted to the night sky they will see that night outside as well as not have stars "get in the way". By the end of the presentation they will be so dark adapted that giving them that pure black night sky will indeed induce a response. And I'll bet that's what they'll remember from the whole show.
"You should have seen all the stars, wow!" They'll probably come back and bring others, and that's what it's all about, isn't it???
Posted by: mrgare5050 Jan 11 2007, 05:26 AM
good points all around! the discussions have endless potential, 'wow' vs managing expectations (if that kid in the corner goes out tonight and doesnt see what he saw in the planetarium, will he want more or simply go back to xbox?), emotional exhileration vs. science, enhanced images vs reality, it goes on and on. it gets down to what is the purpose of a show, entertainment, education, inspiration, or a little (or a lot) of all of them mixed in. i think you guys are right on in advocating a blend, for example in my manifesto i say tip the horizon and show people the southern cross to ignite that mystery etc. i suppose all this has been debated for years. in the end, as operators of our own theaters it will inevitably come back to what drives US, and rightly so, that we have the unique opportunity to share a little part of our own souls with other souls. isnt that lovely ! gare
Posted by: Ron Walker Jan 11 2007, 10:16 AM
Your right "what drives us". If we didn't have this drive would we even be building planetariums in the first place. Why would anyone (in their right mind) want to build a planetarium in the first place. I'm doing it an am not at all sure why. :roll:
I've taught college level courses for over ten years and the only way I ever got through was be being a little entertaining. But that could be just because that was the way I learned best.
How many of you out there remember the old "Bell Science Series" of TV programs that then became a mainstay of educational support programs in high school in the 60's. I loved them and still do. Some of them are available on DVD and the entire series was available on laser disc. I have them all and used them in teaching my daughters. They are fifty years old, but the basic science is still good. My girls took to them the same way I did.
Education through entertainment (in my opinion) always works, which is why a bit of dramatics doesn't hurt. If one just shows the sky the way it looks outside, there is less wonder about why. The problem is it can't be all entertainment (which seems to be the way a lot of the bigger locations are going). Combine that good old star projector with a tad of "wow" and some of the audience will look for more, which is what were really doing this for (I guess).
Actually that is a good question: Why are we doing this?
Posted by: Launch Vehicle Jan 11 2007, 04:12 PM
Gentlemen, amen to all of the above. Ron, with regard to your last question- the very fact that someone who has put so much into this near-religion, and can still ask himself why, speaks to human emotions rich and deep. If we could easily put a finger on it, all this projected magic would be reduced to the level of Golf. I change my mind on that---to Tiger Woods, Golf is a religion. When a passion becomes a "religion," it's only fun if you're extremely good at it. Tiny, intense starlight, blazing above a jet black space, has an almost spiritual effect on people-which is why you work so hard to get it right.
Posted by: Hamon Dec 21 2009, 04:49 PM
I had a quick question since the homestar use's disk like the uncle milton planatarium when it projects does the stars cover the whole celing on a flat roof or does the corners look like an acualy circle ? also do the stars move randomly like on the laser stars projecter, and does the shooting star appear randon or in the same place every time ? thank you.
Posted by: Ron Walker Dec 21 2009, 07:38 PM
QUOTE(Hamon @ Dec 21 2009, 04:49 PM) *
I had a quick question since the homestar use's disk like the uncle milton planatarium when it projects does the stars cover the whole celing on a flat roof or does the corners look like an acualy circle ? also do the stars move randomly like on the laser stars projecter, and does the shooting star appear randon or in the same place every time ? thank you.
It projects a circle of the true night sky (the stars in their proper locations) and does a day in about 12 minutes if I remember correctly. The shooting star appears at the same physical location each time but because the sky is rotating about, it appears to be in a different constellation each time.
Posted by: Ron Walker Mar 29 2010, 11:17 AM
I receive a fair amount of correspondence off of the threads and from time to time get questions that might be of interest to others. Thus the following.
QUOTE
Hi Ron,
I've just been having a look at the post regarding Homestar planetarium projector.
I was wondering if you could tell me how this works. When I first saw the images it looked as if it was a 3D sculpture made from Fiber optic lights suspended then I saw it was actually a projector. Can you tell me how you are able to get the 3D effect you have and also how you are able to project onto black.
Kind Regards,
Jodie
Hi Jodie and welcome to OCP.
I'm assume you are talking about the review found at: www.observatorycentral.com/index.php?showtopic=504&st=0
I'm not at all sure which picture you're talking about. I'm assuming that it is either the final picture in post #4, or the first three pictures in post #8. The picture in post #4 is of a cathedral ceiling that is 12 feet high. It is white between the darker beams. The picture is simply a 30 second time exposure of the projected image on the ceiling which looks very much like what one sees with the naked eye. The three pictures in post #8 are shot the same way but the projection is in a small white dome. Because of the curvature of the dome, the projected sky looks much more realistic and perhaps more "3D" but all of these pictures are actually just of a "2D' projection on a dome.
The projection surface is white and the photographs were taken in a totally darkened room. Without any "extra" light, the surface will look black except where the stars are projected, thus creating the illusion of a dark sky full of stars.
I am going to post this on the thread listed above as I believe there are others that may have the same impression and question.
Again welcome to OCP.
Posted by: xiaoshatongxue May 31 2012, 12:41 AM
Talk about Miniprojectoronline.com in here and it is therefore some weaker than Miniprojectoronline.com 1. But it's all good and why it is called a mobile phone the projector. You can have any of its place, suitable for in your pants pocket 2 back to 1 GB of internal memory, you can download films or pictures, and display it whatever you want to. If the 1 GB is not enough, you can insert 1 scan disk memory card, and make room for anything you want Miniprojectoronline.com
Posted by: newfromCANADA Nov 20 2013, 12:28 AM
Hi,
I am very very interested in buying the homestar Extra for home. I live in BC Canada. Does anyone know where I can buy this? thanks so much
Just a quick news flash.
Aaron Phillips just sent me a "HomeStar" planetarium projector for review.
He is the owner of "The Karakuri Corner" which imports a lot of nifty "toys". He is the distributor of the two other planetarium "pin-hole" projectors reviewed on these pages. I look forward to reviewing this unit because it is optical "lens" projection rather then "pin-hole" and should be very interesting as to the quality of sky.
More to follow.
Check out the various "goodies" at Aaron's site.
www.karakuricorner.com
Posted by: mrgare5050 Dec 14 2006, 01:54 PM
OMG! i have been wondering what the homestar does for soooo long. the thought comes then, what if you combined it with one of those mirrors yall have been talking bout (thats tennessee talk)...
gare
Posted by: Ron Walker Dec 18 2006, 04:13 PM
This is not the full review, it will follow. All I can say is BUY ONE NOW!!!!.
Yes, it's expensive. $240 for a toy planetarium. Outrages you say at first, but the image this "toy" puts out is truly outstanding!
Just a bit of how it works and then a couple of pictures to wet your appetite. If your not planning on spending really big bucks or spending untold hours building (and even if you are) this little machine is for you.
First I can tell you this machine is basically a small slide projector. It makes use of an excellent wide angle lens to project its star field on any flat surface. I plan to make some further experiments with projection into a dome and into a dome mirror, but they will follow later.
The image projected can be most apply compared to a rotating star chart. We all have one of these. Dial it to and day and time and it will show you (on a flat two dimensional plane) what stars are up for an average mid Northern latitude.
This projector is set up for Japan and will work very well for all of us.
Now I'm planing one of my typical reviews as time goes on but it will take a bit of time to prepare so I just wanted to give you all a heads up as to my first impression of this thing.
My "media room" is the largest in my house and has a cathedral celling 12 feet above the floor at the peak. There are large beams that are placed six feet apart that span the distance from the peak beam to the room walls. Between these beams is a white ceiling. From the floor, this little device projects a sky approximately 18 feet in diameter.
Now my first experience with this "toy" was nothing short of jaw dropping. An internal motor rotates the sky around in six or so minutes and I found myself laying on the floor looking up at this rather beautiful sky. The impression being that the white sections of ceiling between the beams were actually glass panels and I was looking up through them at a most spectacular sky!
I must have been laying there for a while, finding constellations, for my wife came in wondering where I was and what I was doing. Upon looking up all she could say way "wow" and then joined me on the floor looking up. I pointed out stars and constellations to the best of my ability and we must have been there the better part of an hour before reluctantly going to bed.
I have taken a few pictures to try and convey to you how "spectacularly" this projector works. The only comparison are the two projector kits I have put together and I will show you their output.
I do want you to know, however, that if you would like a small planetarium that probably looks better then anything available commercially for under a couple of grand, and you don't plan on building a dome to project in, this little unit fills the bill.
The following picture is a look up from my floor looking at the projection on my ceiling as described above.
imageshack.us
Posted by: Ron Walker Dec 18 2006, 04:36 PM
This picture does no justice to this projector. My first image was a ten second exposure with a very rough focus. The unit in reality projects extremely sharp star-fields.
Again the original star-field.
imageshack.us
As a comparison I placed the two other planetarium kits at the same location and took pictures of their projections. They were much dimmer so these photos are 30 sec time exposures.
First the $30 planetarium kit:
imageshack.us
The star images are a bit elongated because in a pin hole projector one is basically just projecting an image of the bulb filament up on the screen. It is easy however to make out the constellations. Again, a good basic teaching tool.
The $50 planetarium kit:
imageshack.us
While there are many more stars, the constellations are much harder to find, and the size of the first magnitude stars is almost laughable.
I went back to this new projector and did a 30 sec exposure as well for a true comparison.
imageshack.us
Constellations easy to find, even Cassiopeia in the Milky Way. I could fall asleep under the stars every night! No problem, there is a self timer to turn it off. But how long will the bulb last, no problem as it's an LED. Remember a true optical lens projection planetarium does not rely on a small filament for pin point stars.
There will be more to come about this truly unique unit.
Posted by: Ron Walker Jan 6 2007, 03:13 PM
OK, a little more about this projector. First it is an optical unit. That is unlike most small planetarium projectors that use "pin-hole" or simple light and shadow projection, this unit uses an actual lens to project the slide of the star field. Designed by the same fellow who designed the "MegaStar" professional projector, this unit only uses one lens for the entire hemisphere, while the big brother uses 18. This is also true of the Zeiss and Goto larger projector and is why their star fields look so good. It is also why this unit costs as much as it does. However, I would rate its cost as a bargain.
imageshack.us
This first picture shows the unit with projection lens pointing up. The lens is surrounded by a large "focus" ring which allows focus from just a few inches to probably infinity. Please note a second smaller projector to the right of the main one. This is also an optical projector and projects a meteor "shooting star" about every thirty seconds or so. This projector is motor driven by the same drive that rotates the sky "diurnal motion" of the sky which runs a day in about ten minutes or so. The meteor is always in the same location with respect to the projection surface which gets old, but since the sky is constantly changing most would not notice unless observing for some time.
imageshack.us
The slide that is projected is circular and beautifully made. The black around the stars is extremely black thus projecting a most beautiful star field. It is round so that when inserted into the projector the star plate can be easily rotated by the motor mechanism within the unit.
imageshack.us
The star plate is inserted into the slide carrier and slid into the center of the projector just above the operational controls. Two slides are included. One of the sky as seen from Japan (works fine for most of North America) and a second one with constellation outlines (the connect the dot kind). It is my understanding that a disc for the Southern Hemisphere is also available for an additional price.
Posted by: Richard B. Drumm Jan 6 2007, 03:30 PM
I like it! Especially the Milky Way image!
Verrrrry Nice!!!
Now all we need is a cheapo, easy-to-setup dome...
Rich
Posted by: Ron Walker Jan 6 2007, 03:45 PM
The projector is powered by 5 volts DC from either a "wall wort" or a small battery case. Instructions are all in Japanese and thus useless to me as well as an audio CD which has a bunch of high school students talking in Japanese about the night sky (I guess). The controls on the projector are straight forward and in English.
imageshack.us
From right to left they are; POWER (turns the unit on and off); SS (Shooting Star-Turns the lamp on and off for the shooting star projector); MOVE (turns on the motor to move the star plate and SS projector motion. This is labeled N and S but I think it should be labeled E and W.; TIMER (there are three times 15, 30, 60 minutes which will automatically turn the projector off after the indicated time periods so you can fall asleep under the stars.
As I mentioned before, the light source is a very bright LED with a daylight color temperature, giving the stars a very realistic "cold" blue look. The SS projector has its own LED thus it should be a long time before you ever need to change a lamp!
A small DC electric motor drives a gear train that supplies rotational power to a rubber roller which is in contact with the outside edge of the star plate, rotating it around in about 10 minutes or so. There is also a small rubber belt which delivers power to the SS projector. If anything would "die" in this projector it would be this, but it appears very well built and should last a long time.
I have shown you how this projector looks reproducing the sky on a ceiling and I think all of you would be very pleased with its performance. For those of us "really" into planetariums, the question of how it would work projecting into a dome or hemispherical mirror comes up.
Posted by: Ron Walker Jan 6 2007, 04:36 PM
Rich you are so right.
I have been putting together an experimental dome approximately four feet in diameter to make as many mistakes as possible before attempting the construction of the large one. It is far enough along to use in this experiment. The trials and tribulations of dome construction can be found elsewhere on this forum.
As I have said, this projector projects a beautiful reproduction of the night sky and as Rich has commented on, the Milky Way is outstanding. Projected onto a flat wall or ceiling the reproduction is much like a flat star chart (wheel). The question is how well would the sky look projected into a dome. The answer in a word is "spectacular".
I have not mentioned this before, but the system is designed in such a way as to accurately rotate the sky around the pole star. In order to fill the entire four foot dome, the projector needed to be placed about two feet below the spring line (horizon).
imageshack.us
Here is a view looking directly up into the dome. The wood circle at the top is part of the support structure of the dome and will be covered by a circular white plate. You can, I believe, get a fairly good idea of how good this looks. You can easily find the big dipper pointing to the north star with the Milky Way high overhead as in summer. I did not have a wide enough lens to get the entire width of the dome in the shot, but let me assure you this look fantastic.
imageshack.us
Looking from the side across the dome, you can see the dark "spring line" support at the top. The stars remain sharp and fairly round even at the edge of the dome.
imageshack.us
Another view at a different time of year/night from the side.
If I ran a small or large museum/planetarium and had an exhibit about the Milky Way, this set up would be in the center of the room!
The final experiment was projecting this unit into a dome mirror. First a shot of the ceiling with the projector projecting directly up. The image is approximately 12 feet away and the entire sky is approximately 18 feet in diameter.
imageshack.us
Again, the feeling that I was looking through glass panels between the beams.
imageshack.us
Now the image not only fills the entire width of the room, 30 feet, but also projects down the walls to the floor. This shot is of the same area as the picture before and you can see the real negative to this type of set up. The larger the angle on the dome mirror to the projector, the larger and more elongated the star images become. This is, however, not how this type of projection would be used, as a computer would be required to "correct" for the distortion. I have reservations about this type of projection and am coming to the conclusion that it should be used for "special effects" only. The main star field should be projected by a good old optical projector, or if you must have video projection, use a system that uses an extreme wide angle "fisheye" lens.
Anyway, as to the "HomeStar" projector. Buy it! If you are at all into planetaria but don't want the expense and hassle of construction, you would be hard pressed to find a better introduction into the indoor night sky.
Posted by: Launch Vehicle Jan 8 2007, 12:48 PM
Ron, I have a 100" fabric dome. Based on your observations - and depending on how it's positioned - what percentage of its inner surface might be covered by Homestar's field without noticeable distortion or bloating of the stars? Also, how dark is the background sky? Any light leaks? At your projection radius, approximately how big was Sirius? Thanks!!! -Bob
Posted by: Ron Walker Jan 8 2007, 03:08 PM
Hi Bob,
My experimental dome is about 48" in diameter and the projector needed to be about two feet below the spring line for it to fill the entire dome. At twelve feet the projector would project an image approximately 18 feet in diameter. I would guess that you could fill your entire 100" dome with the projector placed 4 to 5 feet below the spring line. This will fill the dome all the way down to the horizon.
There is a slight elongation of the stars (as one would suspect) as they approach the horizon but this is slight and not bothersome to my eye. Now I am a bit of a perfectionist so I would think most would be very happy with this unit. As it is an optical lens-ed projector the stars are projected as very small and fine dots.
The designer has ( in most of his projectors) made the brightest stars overly large, but not anywhere as big as in his other "pin hole" projectors. I'm guessing Sirius would be about 1/2" in diameter on your dome. If I were making it, I think I would have made the first magnitude stars a bit smaller, but the other aspects of this machine (especially the Milky Way) are so outstanding that you will soon overlook the shortcomings.
Since it is optically projecting a "kodalith" type "slide" the background is jet black, as good as any optical projector of this type. Looks like a Zeiss sky background. Black as pitch, you will not be disappointed. Also the projector is designed extremely well so there are no light leaks either up at the screen or down towards the floor. When working in a dark room it is actually hard to see the projector.
If there is any drawback at all it is that the projection disk is designed for the latitude of Tokyo, Japan and can not be adjusted from that point without leaving some of the dome without stars. Since this is about mid America the unit is very useful as a "home" teaching tool.
While it is not perfect by any means, for $240 you would be hard pressed to find or make anything near this good.
Posted by: Launch Vehicle Jan 9 2007, 07:24 AM
Thanks, Ron. I think many of us could live with a 1/2" Sirius. It would be interesting to see if those stars near the horizon could be sharpened with some sort of overlay corrector lens. Anyway, who says a dome must be completely hemispherical? Some of those flattened ceiling "half domes" (used to enhance the placement of high-end chandeliers) might be just the ticket in a dual-duty family room. Perhaps this could be combined with your evolving dome setup -- by blotting out all the stars outside the galactic plane, and carefully "registering" what is left, Homestar might serve as the ultimate full sky Milky Way projector. One final question, the constellations outside the galactic plane were easy to make out in your photos. Were they more difficult to trace inside the Milky Way?
Posted by: Ron Walker Jan 9 2007, 10:58 AM
Hi Bob,
The beauty of this hobby is in the experimentation. If you are happy with a dome starting at 45* up, go for it. I was very happy with it on a flat ceiling just because it was so spectacular. I was more impressed in the full dome (even though it was small at 4 ft.) because it just looked more like the sky outside as to where the stars were in relation to my viewing perspective.
A corrector lens might work, but I kind of doubt there would be a stock one. The cost of manufacturer would be so high as to make the answer moot. If they made star plates for the entire sky (like the plates on the Chronos) I would be tempted to get 32 of these machines and make a true optical star projector! I would probably black out the first magnitude stars and add separate brighter projectors for them but all this is wishful thinking.
As for the constellations in the Milky Way itself. The pictures I took both in the dome and of the ceiling do not do the image justice when compared to the naked eye. I can very easily see Cassiopeia and Cygnus the swan as well as Lira the harp. It is like the first time seeing a Zeiss sky. After you start breathing again and start looking around, the constellations become visible amid the 10K stars.
While the last thing I need right now is another planetarium projector, I'm thinking of getting one of these just for the way it projects the Milky Way. More for a separate exhibit with the four foot dome about the Milky Way. If I could incorporate it into my evolving machine then there would be no question, I'd buy it yesterday, but it is designed to be the entire sky from one latitude and would not work properly when one moved to different locations on the Earth.
With other slides It could be turned into a special effects projector as well since it has such a wide angle lens. Might be worth the cost just for the lens. Decisions, decisions....
As to star sizes again, the stars projected on my ceiling are about twice the size in diameter as you would expect in your dome if you filled the entire thing. Do to the time exposure and not perfect focus they are, if anything, larger in diameter then they truly are. To get an idea of size, the bottom of the large beam is six inches and the small beams are four inches. Only the first magnitude stars approach 1/2 inch in diameter so they would be less then 1/4 inch on your dome. However, remember, the stars are closer to you so they would appear very much the same size no matter how far you projected them away.
No planetarium projector is perfect and this one sure isn't. Remember the original Zeiss Mark II projected Sirius two inched in diameter. True it was a 68 foot dome, but that star sure looked like a circle. They soon added separate projectors for all the first magnitude stars and all was well. Again remember this is only a $240 projector, and in my very humble opinion, well worth it. If you don't like this, start saving your money, because the next stop is "The Twilight Zone", and were probably talking six figures.
Posted by: Launch Vehicle Jan 9 2007, 01:45 PM
Ron, wouldn't it be interesting if someone were to do a long exposure of a dark sky (or Zeiss-projected full dome of stars) with a 180 degree fisheye lens, then adapt the resulting transparency to fit Homestar? Of course, this would be done at your local latitude. Better yet, how about some high resolution slides of the moon and planets? Center the nucleus of the Whirlpool Galaxy and watch it spin!
Posted by: Ron Walker Jan 9 2007, 11:18 PM
How right you are Bob. I'm thinking it would probably be fairly easy to make an adaptor for 35mm slides and use them in this projector. That way you could get some pictures (even ones you take yourself) of different objects to use in this machine. 2X2 inch super slides would be great! Not sure about using a "fish eye" lens to take an image but it sure would be a great experiment. The spinning Galaxy would indeed work extremely well.
I'm thinking of some experiments with "ink jet" transparency film and some of the things you could make with that. I'm all ready planning on doing some "constellation outline" figures for my main projector once I fine some good drawings.
My work schedule has gotten a bit heavy this month and there just aren't enough hours in a day to do all the things I want to do. :roll:
Posted by: Ron Walker Jan 9 2007, 11:22 PM
Also I should point out the this projector is set up in such a way as many stars (and constellations) do set and then rise later as the day/year progresses. There not all up there all the time. Just the circumpolar stars at the Tokyo latitude.
Posted by: mrgare5050 Jan 10 2007, 06:35 AM
wanted to get my 2 cents in on this interesting discussion, but dang it, im still smarting from not having 300 bucks to outbid a space toy collector on steve pielocks spare renwalls cosmorama, now here's another expensive yet intriguing 'more than a toy' projector, and this one we've all been looking at and wondering about for a long time!
first of all, its got a meteor projector! that alone makes it cool, use it once a show if nothing else. its small ... small projectors can be moved.. swirled.. as you say ron, and as we said with the smaller kodalith unit, all kinds of interesting special effects come to mind. maybe it could be rotated and then condensed outer to inner like youre being sucked down a wormhole, to the sound of 2001 a space odyssey. stuff like that!
if i had one i'd do the blink test. set it up next to my regular projector and look at one sky, then lights out, then the other .. what would my first impression be? its the old argument, should a sky be real or should a sky fire the imagination by being just a little beyond .. oddly, one of my best memories of the adler shows i attended was the one where the guy showed the dull sky we were all used to in chicago, even in the 60's, the one where i poked around with my 2.4 inch and filled notebooks of excited entries. THEN he turned up the stars .
over the years ive sortof more gotten used to fighting to see them, sometimes my perfect planetarium sky gets boring.. no clouds to see them poking out of .. no dwindling light cones over cities as we head to the country .. no moon .. airplanes .. somehow this quest for a perfect sky sometimes loses the charm .. the too many star worries that at times i feel like im the only one who shares .
anyway just some thoughts on this remarkable projector! gare
Posted by: Launch Vehicle Jan 10 2007, 10:33 AM
Gare, exaggerations are what make planetariums "work". Remember Zeiss' one (2? 3?) minute Moon? -Bob
Posted by: Ron Walker Jan 10 2007, 01:01 PM
Gare,
The seeing conditions as they look from Chicago is exactly the reason that you need to be able to show a full sky. You can start (as they did at the Adler) with only a view of a couple of hundred stars (or even fewer as I've seen from some cities) and then talk about the effects of light pollution or the real reason the ancients saw creatures in the sky and we can't. Because they could see stars that we can't.
I remember the Adler shows where they would take the down to the Chicago level of light pollution and talk a little about finding your way around the night sky. You could see the Big Dipper but not all of the Little Dipper. The the lecturer would use the big Zeiss as a time machine and say he was going to take us straight up three miles above all the smoke, haze, and light pollution and "see the true beauty of the night sky". There would be that great "gasp" from the audience that any previous attendee would know was coming.
The sad fact is that a full and spectacular Zeiss night sky is not an exaggeration but an accurate depiction of what we should see an a clear moonless night.
I, for one, will know that I have made a projection display worthy of sharing when I get my first (gasp -Oh My [Wow]) from any member of the audience. Some might look down on that as a "bad teaching attitude" or "ego showing" or whatever, but (being a bit of a showman) that's what will make me feel good about doing and sharing this fascinating hobby.
Posted by: Ron Walker Jan 10 2007, 01:07 PM
Another thought. Remember that you can always do an introduction to the night sky and constellations with the star intensity down a bit and the twilight light not totally off. This way you can get your audience adapted to the night sky they will see that night outside as well as not have stars "get in the way". By the end of the presentation they will be so dark adapted that giving them that pure black night sky will indeed induce a response. And I'll bet that's what they'll remember from the whole show.
"You should have seen all the stars, wow!" They'll probably come back and bring others, and that's what it's all about, isn't it???
Posted by: mrgare5050 Jan 11 2007, 05:26 AM
good points all around! the discussions have endless potential, 'wow' vs managing expectations (if that kid in the corner goes out tonight and doesnt see what he saw in the planetarium, will he want more or simply go back to xbox?), emotional exhileration vs. science, enhanced images vs reality, it goes on and on. it gets down to what is the purpose of a show, entertainment, education, inspiration, or a little (or a lot) of all of them mixed in. i think you guys are right on in advocating a blend, for example in my manifesto i say tip the horizon and show people the southern cross to ignite that mystery etc. i suppose all this has been debated for years. in the end, as operators of our own theaters it will inevitably come back to what drives US, and rightly so, that we have the unique opportunity to share a little part of our own souls with other souls. isnt that lovely ! gare
Posted by: Ron Walker Jan 11 2007, 10:16 AM
Your right "what drives us". If we didn't have this drive would we even be building planetariums in the first place. Why would anyone (in their right mind) want to build a planetarium in the first place. I'm doing it an am not at all sure why. :roll:
I've taught college level courses for over ten years and the only way I ever got through was be being a little entertaining. But that could be just because that was the way I learned best.
How many of you out there remember the old "Bell Science Series" of TV programs that then became a mainstay of educational support programs in high school in the 60's. I loved them and still do. Some of them are available on DVD and the entire series was available on laser disc. I have them all and used them in teaching my daughters. They are fifty years old, but the basic science is still good. My girls took to them the same way I did.
Education through entertainment (in my opinion) always works, which is why a bit of dramatics doesn't hurt. If one just shows the sky the way it looks outside, there is less wonder about why. The problem is it can't be all entertainment (which seems to be the way a lot of the bigger locations are going). Combine that good old star projector with a tad of "wow" and some of the audience will look for more, which is what were really doing this for (I guess).
Actually that is a good question: Why are we doing this?
Posted by: Launch Vehicle Jan 11 2007, 04:12 PM
Gentlemen, amen to all of the above. Ron, with regard to your last question- the very fact that someone who has put so much into this near-religion, and can still ask himself why, speaks to human emotions rich and deep. If we could easily put a finger on it, all this projected magic would be reduced to the level of Golf. I change my mind on that---to Tiger Woods, Golf is a religion. When a passion becomes a "religion," it's only fun if you're extremely good at it. Tiny, intense starlight, blazing above a jet black space, has an almost spiritual effect on people-which is why you work so hard to get it right.
Posted by: Hamon Dec 21 2009, 04:49 PM
I had a quick question since the homestar use's disk like the uncle milton planatarium when it projects does the stars cover the whole celing on a flat roof or does the corners look like an acualy circle ? also do the stars move randomly like on the laser stars projecter, and does the shooting star appear randon or in the same place every time ? thank you.
Posted by: Ron Walker Dec 21 2009, 07:38 PM
QUOTE(Hamon @ Dec 21 2009, 04:49 PM) *
I had a quick question since the homestar use's disk like the uncle milton planatarium when it projects does the stars cover the whole celing on a flat roof or does the corners look like an acualy circle ? also do the stars move randomly like on the laser stars projecter, and does the shooting star appear randon or in the same place every time ? thank you.
It projects a circle of the true night sky (the stars in their proper locations) and does a day in about 12 minutes if I remember correctly. The shooting star appears at the same physical location each time but because the sky is rotating about, it appears to be in a different constellation each time.
Posted by: Ron Walker Mar 29 2010, 11:17 AM
I receive a fair amount of correspondence off of the threads and from time to time get questions that might be of interest to others. Thus the following.
QUOTE
Hi Ron,
I've just been having a look at the post regarding Homestar planetarium projector.
I was wondering if you could tell me how this works. When I first saw the images it looked as if it was a 3D sculpture made from Fiber optic lights suspended then I saw it was actually a projector. Can you tell me how you are able to get the 3D effect you have and also how you are able to project onto black.
Kind Regards,
Jodie
Hi Jodie and welcome to OCP.
I'm assume you are talking about the review found at: www.observatorycentral.com/index.php?showtopic=504&st=0
I'm not at all sure which picture you're talking about. I'm assuming that it is either the final picture in post #4, or the first three pictures in post #8. The picture in post #4 is of a cathedral ceiling that is 12 feet high. It is white between the darker beams. The picture is simply a 30 second time exposure of the projected image on the ceiling which looks very much like what one sees with the naked eye. The three pictures in post #8 are shot the same way but the projection is in a small white dome. Because of the curvature of the dome, the projected sky looks much more realistic and perhaps more "3D" but all of these pictures are actually just of a "2D' projection on a dome.
The projection surface is white and the photographs were taken in a totally darkened room. Without any "extra" light, the surface will look black except where the stars are projected, thus creating the illusion of a dark sky full of stars.
I am going to post this on the thread listed above as I believe there are others that may have the same impression and question.
Again welcome to OCP.
Posted by: xiaoshatongxue May 31 2012, 12:41 AM
Talk about Miniprojectoronline.com in here and it is therefore some weaker than Miniprojectoronline.com 1. But it's all good and why it is called a mobile phone the projector. You can have any of its place, suitable for in your pants pocket 2 back to 1 GB of internal memory, you can download films or pictures, and display it whatever you want to. If the 1 GB is not enough, you can insert 1 scan disk memory card, and make room for anything you want Miniprojectoronline.com
Posted by: newfromCANADA Nov 20 2013, 12:28 AM
Hi,
I am very very interested in buying the homestar Extra for home. I live in BC Canada. Does anyone know where I can buy this? thanks so much