My question is; how do I establish what quality of mirror will be needed for This level of magnification.
I do not know how to calculate if I would need 4 wave, 1 wave or 1/4 wave and there is a LARGE price difference.
I am hoping someone has used one of known mirror quality, for a known magnification.
Or even better is someone knows how to calculate this.
My 5c worth is that the worst part of the optical train dictates how good your view is going to be: and 1/4 wave is the only one of these that wont make your image worse. Anything less is a compromise: but if you are going to compromise I would suggest you don't go for 4 wave... I suspect it would be like looking at a reflection in a lake, or using your binos through a window!
Do you have a link to the glass source I could look at ? It really depends on the kind of error and how localised it is . 25X will certainly not require 1/4 wave quality nor would the average binocular be any where near this quality .
Thanks
I haven't yet found a glass source as I dont know what I am asking for.
I am aware that Edmond Scientific sell some front surface mirrors but still searching for other sources. There are some on ebay but I need to know what questions to ask to ascertain if they are suitable.
A good quality refractor objective is capable of up to 50x magnification per inch of aperture. 25x100 binoculars are of lower quality and are working at about 1/10th of that. You'll be looking at an angle much of the time so you need to at lease double the wavefront error. Maybe something better than this but you definitely don't need a 1/4 wave mirror.
If you want to get an idea on the cheap, try a piece of new dark tinted plate glass on the moon Jupiter or Sirius. Get one side sand blasted or grind it yourself then spray paint the sandblasted side with black paint. View them at different magnifications.
The ones from "Big Binoculars" are 1/4 wave and should be great but they are 4 inch by 9.5 inch I could use 2 of these line them up right. With a 4 inch objective lenses I am guessing they will need to be absolutely perfectly aligned.
I saw the ones at edmund optics but wasnt sure if 4-6 wave was enough.
I emailed FSM to try establish what quality their mirrors are.
Graham
Which Mirror for a Binocular reflector mount ??
I am hoping someone has done it or knows how to calculate it. 
