Lyndhurst Garden House

Lyndhurst Garden House
Lyndhurst Garden House

Monday, February 26, 2018

Laser Projectors and Planetariums

Here is a new inexpensive light show projector device I purchased for my living room Relax scene with the main lights turned off.  The light show is very colorful and nice.  My friend thinks it is great.  

I bought it as a replacement for the now very faded (the lava has turned nearly white from fading) and somewhat dysfunctional 25 year old lava lamp, which I decided isn't good enough anymore.  Lava lamps generally take awhile to warm up, but the worn-out lava in my old lamp takes a couple hours to get moving, and when it does finally get moving, the faded white and broken-into-bits lava isn't very cool looking.  I could still use the lava lamp base, however, to house a multicolor LED bulb.  I use the base of another worn-out lava lamp for the soft yellow light in the Kitchen.

One minor annoyance for me is that when I switch on the Relax scene from my Kitchen Insteon multi-switch panel, it can switch on the soft light in the Kitchen, but in the living room it takes an additional press-and-hold on the pushbutton of the light projector itself, which is on top of a bookcase.  Since I have an auto-turn-off feature in my Insteon program itself, I don't need the auto-turn-off of the light projector, I could just bypass the internal switch if I could find a way to do that.

Here's a home laser show projector that looks pretty interesting, from a company which sells laser projectors from very cheap to very expensive (this one is in the middle of their range, about the largest one could imagine in a small home).  This looked like my "dream" home laser show projector.  But I decided I should focus on getting a real video projector and screen for the living room before getting an extra frill of this cost.  In the past year, I've seen very nice video projectors at the houses of 3 of my friends.  Since I have a movie party every month, I'm way behind on getting my own video projector.

I was also inspired to get a home planetarium.  Home planetariums have had their ups and downs over the years.  This appears to be a down phase.

Here's a page devoted to a Planetarium Museum which has some very impressive planetariums used in museums and schools over the past century.

Here's a good discussion of the leading home planetariums that were available recently.  I'd love to have the Homestar Extra, but they are now collectible and collectors are asking around $1500 on ebay.  The #2 rated Uncle Milton Star Theater Pro is similarly unavailable, with collectors asking well above $200 for used units.  But I found I could buy the identical Nashica online for around $200 brand new from a seller in Asia.  Then since it is one of the 3 machines supported by Miller Engineering, I was able to buy their upgraded star discs.  I got one upgrading my star count from 10,000 to 1,200,000, I got another showing Aurora Borealis, and a 3rd showing the star constellations (which have always been nearly impossible for me to figure out...and one big reason why I wanted a decent planetarium since I was 3).  Though let me say I find "my" constellations...such as the Big Butterfly...more intuitive than the traditional ones (Orion the Hunter).

Update: I now have my Nashica planetarium projector with 3 discs from Miller Engineering.  ME is correct, the star discs that come with the Nashica are not realistic in the least.  Imagine bright stars all over the sky, that's what the Nashica looks like.  The ME discs are quite realistic, even with the low power of the Nashica light (which actually seems quite sufficient).

Now, however, I see a major fly in the ointment.  NONE of these disc-based projectors can paint anything close to a realistic sky for two big reasons:

1) They don't have the Moon and Planets!  This goes way back, home planetariums have basically never had the moon and planets.  To do the planets, you need either a complicated mechanism which positions each planet image individually, as in the classic and gigantic Zeiss "dumbbell" shaped planetariums in big theatres (like my first love, the Planetarium at Los Angeles Griffith Park, which my family should have taken me to monthly instead of 2 times), or you need computerized imaging, which is still difficult even for big million dollar planetarium projectors (the most expensive Zeiss now available combines "static" star imagery which is simply too detailed for any kind of video system with the dynamic objects like planets synthesized in synchronized video...an enormous amount of engineering went into making the two very different things synchronize).

Why do they call these things "Planetariums" if they don't actually show the planets???  (I've often wondered that.  I was first very disappointed in "planetarium software" when it first came out for that very reason.  I want to see which of the objects in the sky are the planets!  I want to see where the planets are!  I complained about this to a maker of early planetarium software and they brutally brushed me off as some kind of idiot.)

In the big Zeiss "dumbbell" projectors, the Sun, Moon, and Planets are projected by circular rotating parts in the middle of the dumbbell.  Each planet must move separately against a fixed background of stars.

2) They can't actually paint the sky at your latitude!  What you get, with all these projectors like the various "Homestar" models up to and including the vaunted and long discontinued Homestar Extra which scalpers are charging $1500 for on ebay, and the Nashica and similar units, is the view from either the north pole (with the "northern hemisphere"discs) or the south pole (with the "southern hemisphere" discs).  In this polar view, the stars simply circle round and round.

This is why the big dumbbell projectors have that shape.  One end of the dumbell projects the northern hemisphere stars, and the other end projects the southern hemisphere stars.  If one end is straight up, you get the view from the north or south pole, depending on which end is up.  To get other latitudes, the dumbbell is tilted at an angle, and the machinery combines stars from the northern and southern hemispheres, changing the combination of stars all night long as the dumbell spins around its horizontal center.  (I figure this "combination" also requires some very sophisticated electronics and mechanics as well, since it always has to cut out all the stars you don't see.)

There is, actually, a way to do this on the cheap.  And that is to have a big ball (or similar shape).  You don't actually need a dumbell shape (which also allows for projecting the planets, moon, and sun, but as long as you are not going to do those anyway, you can just have a ball shape).  You can simply tilt the ball to the correct orientation for any particular latitude, and spin the ball around the resulting tilted axis to show what stars you are going to see that night.

This is actually the principle used in the very earliest home planetarium, the Spitz Jr.  Spitz had gotten started making intermediate size projectors for schools and smaller theaters based on the same principle, but instead of a cheaply mass produced (with considerable ingenuity) plastic ball with pin point holes in it, they used a bigger polygonal shape with actual glass lenses for stars and groups of stars--but that is going to be a lot more expensive than a ball with pin-point holes in it, but produce a far more realistic image, and while it may be much less expensive that the top Zeiss models, it's still going to be far more expensive than a plastic ball.

The whole raft of more recent home planetariums have mostly given up on that principle for using circular slides with single lenses which can, in principle, and with the Miller Engineering discs, project a somewhat realistic looking sky full of stars, but with the obvious limitation that it's only at the north or south pole, and if it moves it just goes round and round the center.  Boring!  I mean the motion part is boring, it is still interesting to see all the stars in their natural arrangement.

Now, there is one home planetarium projector based on a similar principle as the Spitz Jr, but using printed imagery on the surface of the ball.  It has this feature: you can set the latitude!  And, you can see the stars process over the nighttime from that latitude.  This is the iOptron.  People complain about many aspects of this home planetarium, including the realism, but it's cheap, and I've ordered one, and will report.

The ultimate "home" planetarium projector, if it had ever been made, would have been the Nova 100.  It had the rotating star ball AND two planets, which could be assigned.  It was never put into production.  The intended price was $600.  It was actually intended for elementary school classrooms.  It was designed by Harmonic Reed, who had gotten started manufacturing planetarium projectors with the Spitz Jr for Spitz.  The Spitz company itself moved upmarket to bigger and better projectors than the small institution A series that made it successful to such giants as the STP and STS, which challenged the Zeiss projectors that had originally inspired the company founder to make low cost units.  These were the glory days of the Space Race, when science funding nationwide got an extra federal boost, and when things like the Arpanet (predecessor of the Internet) got started.

Harmonic Reed did however actually make a very nice high school planetarium projector, the Nova III, which sold for $2000 (about $20,000 today).  It's suitable for a 14 foot dome...could it work in my living room???











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