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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

twilight factors (1 Viewer)

salty

salty

geordie birder
you here about the twilight factors on binos, but never for scopes. can any egg heads out there work out mine for the apo televid 77? prehaps from 20x up to 60x? its bugging me and i aint too bright when it comes to square roots. p.s. i know my binos (10x42) are 20.5 cheers.
 
salty said:
you here about the twilight factors on binos, but never for scopes. can any egg heads out there work out mine for the apo televid 77? prehaps from 20x up to 60x? its bugging me and i aint too bright when it comes to square roots. p.s. i know my binos (10x42) are 20.5 cheers.
Click to expand...

Right, hope this is correct:
@20x TF = 39.24
@30x TF = 48.06
@40x TF = 55.49
@50x TF = 62.04
@60x TF = 67.97

Unfortunately these figures do not say anything about glass types, coatings or prisms. Mathematical calculation only.
 
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