-DannyMy warehouseMy Channel
Quote:Perhaps the best approach is to obtain not one monolithic mirror, but two smaller ones of, say, 80X110mm. You're more likely to get flatter specimens, and you can mount one so as to refine collimation.
Jeff Morgan - Wile E. Coyote School of Telescope Making
Quote:I love my SkyWindow for my Fuji 10x50's. But if I wanted to go high-power I would definitely get a pair of Newtonian diagonals. Pricey yes, but the comfort is unbeatable, and SkySafari solves the mirror reversed image "problem"
"A craftsman relies on science when knowledge allows it, tradition and experience when it does not, and makes art whenever he can." 14 built scopes from 4.25 to 18" and a 24" in (perpetual) progress. 15 ATM awards. Co-mounted CPC 1100 EdgeHD/TAK FS-102/Orion ED80T on a trash-cart for when I'm feeling lazy. "Simple minds discuss people. Good minds discuss events. Great minds discuss telescopes." http://stardazed.com/
Quote:That's funny. I was rummaging through my attic this morning and found my old SkyWindow. It seemed like a good idea at the time and really helped with neck comfort, but it wasn't quite flat enough across it's width to keep acceptable bino-collimation with my 14X70 Fugis--no neck ache.
Quote:Note that it's not required to have the two mirrors share a common plane. One can be higher than the other.
Quote:All that's important is that each mirror not have an edge fall inside the circle defined by the entrant light bundle.
Quote:At such a large exit pupil, you can get away with a wavefront error of perhaps 2 waves, and certainly 1 wave, across the objective aperture. This implies a *surface* flatness of 1/2,that, or 1/2-1 wave over 70mm.I know that float glass mirrors are typically rated as having 4-6 waves per inch error, on the surface I'm reasonably certain, which if so is a wavefront error of 8-12 waves per inch on reflection.It's entirely possible to find float glass with portions rather better than this. To illustrate... An older friend observes through 2 sheets of window glass with 100mm binos up to 30-40X. The image leaves much to be desired, but the view for him is serviceable.
Quote:Unfortunately Sky Window isn't being made anymore. Also, I contacted Trico Machining (the manufacturer) and they had no "spare" mirrors left either.What do you mean "SkySafari solves the 'problem'"?