T2 mount & aperture??

Phil-D

Phil-D

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I have a T2 mount attached to a sleeve that fits snugly over a spotting scope eye piece, I use it on a Nikon D7200

Obviously I can only adjust SS and ISO, just out of curiosity, anyone know what determines aperture and what the reading will be?
 
As as I recall F number is the focal length of your spotting scope / diameter of the front lens. Eg 300mm / 30mm = f10? Worth a google.
 
newbie1 said:
As as I recall F number is the focal length of your spotting scope / diameter of the front lens. Eg 300mm / 30mm = f10? Worth a google.
Click to expand...

Thanks Tim, now you've said, that makes sense and I feel I should have known!

The front element is 65mm with a 25x50 wide zoom eyepiece, higher the magnification equals less light, so smaller the aperture

I'll see if I can get some specs on the scope and work out an equivalent focal length, cheers
 
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What’s the spec? 25x50 or 25-50x?

D7200 is a crop? So my guess is something like this - normal focal length for crop is say 35mm so 50x is 1750mm. Divide by 65mm gives f27.

Does that fit for what you see in practice with the camera?
 
newbie1 said:
What’s the spec? 25x50 or 25-50x?
Click to expand...

Sorry, yes should have read 25-50x

You could well be right on the button here Tim (y)

I was talking to a chap the other week who seemed to think that a scope with a fixed 20x eyepiece was equivalent to around 700mm (he didn't say how he knew ) but going off what you say it looks like he was right.

Mine at 25x multiplied by 35 will give a focal length 875mm, divided by 65mm gives an aperture of f13/f14 which sounds about right

Thanks for the help
 
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