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GlennLeDrew
professor emeritus
Reged: 06/18/08
Posts: 620
Loc: Ottawa, Ontario, Canada
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Re: Sega Homestar Planetarium - Off of the Bino to
06/23/08 02:37 AM
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Zoomster,
I suspect that the Homestar lens could project at as small as a 45 degree angle, possibly 60, and 90 tops, so in a dome you'd illuminate a pretty small sector nowhere close to the usual 180 degree hemisphere. I'd be willing to bet, though, that because of the fairly short focal length and/or numerical aperture of the lens, focus would not be a problem on the curved dome surface--the depth of field should be able to accommodate it.
I'm surprised that you think of the Starlab as being inadequate in some way. For what it is, I feel it delivers a pretty good star field. At least the cylinder which employs collimation lenses for the brightest stars.
Here's one thing I strongly suggest you do for a *much* more realistic presentation, if you don't already. And that's to not have the dome as black as the hobbs of Hades. A really dark interior actually detracts from the effect. Try out a neutral, diffuse illuminator to fill the dome with an even glow more like the real night sky (even the the darkest sky is surprisingly bright). The stars will almost magically appear sharper, and the brightness range will be more realistically represented. Moreover, by varying the brightness, you can effectively simulate light pollution MUCH more dramatically that with the so-called Urban Starfield cylinder.
I tried this out for the first time by simply aiming my flashlight downward at the carpet. The scattered light nicely filled the dome with an even "sky glow."
Cheers!
--------------------
Home-made 11X50 right angle bino, 8.1 deg. FOV
Modified 26X100 bino, 3.5 deg. FOV
Mediocre minds discuss people. Good minds discuss events. Great minds discuss ideas.
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