Re the Bino mirror mounts
I made the mirror mounts myself , not really following any plans
but I found two sites very helpful in designing my own version
http://www.fvas.net/bino.html
http://home.interlynx.net/~mullers/skybox.html
I first built the mirror mount for the 7 x50s. For this I used a First Surface Mirror that I bought really cheaply -a few dollars-from surplus shed
http://www.surplusshed.com/
Somone in another forum asked for dimensions and details so I made up a little poster and I am happy to post that here if anyone is interested.
This worked so well I decided to build a mount for my 20 x80s Oberwerks
For this I couldnt use the surplus shed mirrors-too small so I had to buy a mirror from FS mirrors in the US
http://www.fsmirrors.com/
Before buying from the US I did a lot of research around Sydney and found it would cost almost double -even if I were to buy optical glass and get it mirrored .
So I took a deep breath and forked out whatever it was-the site above has prices - to buy from the US. Freight is expensive though!! I bought an 8mm thick 6 inch by 8 inch mirror
This mount which is made of pine sits on a computer turntable so it moves smoothly in azimuth. I have a handle that I can use to control the mirror angle-the altitude. A clutch mechanism allows the tension with which the mirror axle is gripped to be adjusted so the mirror stays in place when the handle is released yet moves (rotates) reasonably smoothly
Now how does it work?
Firstly notwithstanding whatever they say in the marketing literature, there is some loss of brightness. So it's not as good as looking straight at an object. Is it acceptable? I think so but someone else may not.
Secondly if your binos are even the slightest bit out of collimation this system is very unforgiving. Its a good test for the quality of your binos!
Thirdly it is harder to find things because your maps need to be mirror imaged
But once you are past these issues, the benefit of not having to crick your neck to look up all the time is enormous. You can scan star fields literally for hours without discomfort. You are looking down, its a very comfortable position, you can sweep across the sky slowly, and take your time enjoying the sky
I really enjoyed observing Comet Q4 through this system earlier this year.
The fact that the binos are mounted adds at least a magnitude compared to hand holding.
So, there are pluses and minuses, but for me it works.