ATM Binocular collimation? part OT

[Andrew Grisdale <roadwarrior@techieguy.com>]

Hi all, 

This is 2 questions really, the first is probably off topic,   but here is the only place 
I know to get a knowledgable answer and it has some relevance to the second.

My father has a seemingly excellent pair of Zeiss Jena 20x50 binoculars, we used them 
terrestrially for years, leaning on our elbows on something of course. When finally I got 
a bino clamp and put them on a tripod a couple of years ago, turning them heavenward I 
was shocked to see two of everything, the collimation was so off it made me dizzy trying 
to see anything. Terrestrially this seems hard to notice, maybe the brain can more 
readily match up more complex images. Anyway, this came to mind the other day as I was 
looking at and through a pair of 7x40s in a store, that I could have put on my christmas 
list, and with the store lighting being diffused strip lights spaced real close, I 
realised I didn't have a hope of telling whether the collimation on these was good enough 
for astro or not. So, the question is, is there a simple in store way to check these 
things reliably? 

Secondly. I have 2 fairly similar 40mm refractors (these are old enough to be pretty good 
quality, one pre '70 one pre '80, japanese optics) I want to mount them side by side to 
use as high mag binoculars on a tripod. What would be a good way to go about collimating 
them in a restricted indoor enviroment? The longest indoor space I have is about 30ft, 
doubling this with a mirror will give me 60, I guess that isn't really enough to 
collimate well for objects at infinity if using a single point source. I have not really 
finalised a design for mounting them together, I am thinking ahead to the collimation so 
that my mounting design may ease it. I intend to set them up for my interpupilliary 
distance only. Any advice on how the eyes behave when looking through binocular 
instruments would be welcome also.

thank you for any assistance you can give. 

steady hands and steady skies!

Andrew G.



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