> Hi All,
> I have a pretty basic understanding of optics, but am curious about
> "big" binoculars for astronomy. I get the part about seeing with two
> eyes is better than with one (psychology/physiology/brain wiring). But
> at the distances involved is there any real "stereo" effect?
I get a pseudo stereo effect viewing the moon because the brain seems to take other visual cues like shadows and curves to create 3D. I don't thing stereopsis is the only source of 3D.
On deep sky objects, particularly star clusters you get chromatic stereopsis. The redder the star the more your eye has to converge to concentrate on it due to the chromatic abberation of the eye. The redder the star, the closer it looks. I get this 3D impression only on telescope binos where there is enough aperture to see star colours clearly. What you get is a kind of scintillating effect where the cluster simply looks 3D. Only quite orange stars look `closer' if you concentrate on them. The other stereo effect I get is that the edge of the field is like a porthole into space, only a few feet in front, while the view is `out there'.
This leads
> me to wonder whether what makes big binocs better than a big light
> bucket with roughly twice the gathering area and one of those splitter
> gizmos. Don't want to start a holy war, just suspicious that I am
> of limited understanding on this subject...seems like lots of ATMs
> dream of that big binocular project!
Beamsplitters lose a lot of light, give significant spherical abberation with faster cones of light and also split the same signal. I tried one on my 12" ( I had to remove the focusser ) and found the view far inferior to my 8" binocular. I think they are good for long focus refractors.
In a nutshell, a true binocular give you 40% more light gathering for a given magnification over a similar monocular scope. You get much better contrast, ( dark nebula appear to me ink-black, emmision nebula appear smooth and fluid like ), colours are clearer, fainter mag. limit, and most important they are comfortable. All of these things would be accentuated with larger aperture, i would imagine.
Mark