The HuntingPA.com Outdoor Community banner

1 - 4 of 4 Posts

·
Registered
Joined
·
9,848 Posts
I would choose the 3-9x40. At anything above around 5x, it will gather noticeably more light in lowlight conditions or shooting at night.
 

·
Registered
Joined
·
555 Posts
kudu58 said:
I would choose the 3-9x40. At anything above around 5x, it will gather noticeably more light in lowlight conditions or shooting at night.
I agree, mostly. To expand on it a little here is some info I posted previously on the topic (but on 50mm vs. 40mm):

Glass and coating quality trumps objective size every time. The reason a 50mm obj. "can" be better in low light is that it increases the exit pupil diameter at any given magnification.

For example, the exit pupil of a 40mm obj. set at 9x is 4.4 mm. The exit pupil of a 50 mm obj. set at 9x is 5.6 mm. Most of us have pupils that will dilate to over 5 mm so there will be a slight advantage.

If you move scopes down to 5x, the 50 mm obj. will offer no advantage as the 40 mm scope will deliver an exit pupil of 8 mm, and is about the most any of us can use.

Basically, what it comes down to is this: in scopes of the same quality, a 50 mm obj. will allow you to use a higher magnification in low light.
So, unless the 33 mm obj. has better glass and coatings than the 40 mm obj., I concur with kudu.
 
1 - 4 of 4 Posts
Top