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comparison ATX95 vs ATM80 (amount of light) (1 Viewer)

Gduff

Well-known member
Hi,

I currently own a Swaro ATM80 HD with 25-50x zoom, and I'm interested in the new ATX95 30-70x.
I know it's better to compare images from 2 models at the same zoom, but I would like to know if there is the same amount of transmitted light between the 2 scopes at full zoom, i.e. ATM80 at 50x, and ATX95 at 70x?

These days I'm using my scope near a large river, and I'm always too short for the birds, so that I'm sure I would use the 30-70x at full zoom.

I would like to know if my camera would chose the same ISO speed between the 2 setups, and so if my photo at 70x (on ATX95) would be the same quality as the one at 50x (on ATM80).

Thank you for the answer
 
At 50x the 80 mm scope will appear 39% brighter than the 95 mm at 70x. It's just 1/3 stop in photographic terms, i.e. with the 95mm@70x you would get ISO133 instead of ISO100 (with the same shutter speed and aperture).
 
From what I have read and seen... the light transmission of the new Swaro ATX modular scope is around 91%. The Swaro 80mm ATS is around 87% (with the 25-50 eyepiece), while the Swaro ATM is around 82-83 % (with the 20-60 eyepiece). I haven't seen the specs of the ATM with a 25-50 but I have a feeling it is less. At one time another I had new ATS in 2009, sold it, and eventually bought an ATM. Both scopes used the 20-60 eyepiece and the ATM was measurably difference.

The human eye can discern a difference of 3% or more, so when I moved from the ATM back to a new ATS I recently purchased, it was measurable so I am using that as a gauge that the ATM is still less light transmission than the ATS even if both use the 25-50 eyepiece.
 
I used to use on a loan an ATS 80mm, it was some time ago. I now have a STX 95 and I find it much brighter at low light and clearer. Now, I am relying on memory. I kind of wish I went with the STX 85 though due to portability. I also have a 65mm objective that is very portable, I think the 85mm might be the sweet spot.
 
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