I will be looking for a fixed 8x scope fore nightshooting and have been looking at various premium 8x56 scopes. I was wondering if there is any practicle difference in brightness with 56mm VS 50mm. My thinking is that as we get older, our pupil diameter shrinks down from 7mm when we are young, down to 6mm or so when we pass 40. Therefore is there any night time advantage to the 7mm exit pupil of 56m scopes versus the 6.25mm exit pupil of 50mm? Has anyone (not teenagers with perfect eyes) actualy tested two similar quality scopes with 50 and 56mm objectives?
I want the brightest possible, but didnt want to go for the extra 56mm size if it is wasted on 40 yr old eyes.
I,m talking scopes like Swarovski, S&B, Zeiss, Docter etc

cr,

Yes, I have read that with age a person's pupil diameter gets smaller; which would therefore reduce the amount of light entering a person's eye. Other than accepting this at face value - I dunno - personally can't tell & I'm not a Medical Doctor; furthermore don't want to know all the In's & Out's, just want to hunt when it's dark with the best piece of legally allowed equipment I can afford.....using an artificial light source or a night vision device in conjunction with a scope (aiming device) is illegal in Germany.

I have a a Doctor 2.5-10x48 (pretty good night time scope), an older Zeiss 2.5-10x48 (good night time scope), a Zeiss 3-12x56 (very god night time scope) and a Zeiss 8x56 (excellent night time scope). The straight 8X power with the 56mm objective is the best night time scope for my eyes. It's on my night time rifle and for that specific purpose; it is IMO the best scope I own for my nightime use - period.

Many ask my opinion and the vast majority desire a variable scope. I try to disuade them to forego the variables and go for the straight 8x56 scope's are considerably less expensive than the variables in similar power ranges. Even when I use the two 10X's and the 12X when hunting at night for any length of time they get cranked down to 8X anyway; which is where is see the best.

Yes, in the Fatherland we can hunt at night - all night.

Your pupil of the eye determines the cone of light that will enter the eye. Anything larger than that is unuseable. If your eye pupil dialates to 7mm, which is max for a perfect eye, any exit pupil of the scope over 7mm is not useable by your eye.
For us old guys, that maximum dialation is less than 7mm, so the scope's exit pupil doesn't need to be that large.

Don

I can't answer your specific question, but speaking as someone whose been in bifocals since age 27, I doubt there's much difference. You will find, as you likely know, much better performance from a higher quality scope than a larger objective.

CDNN has a bunch of Kahles for sale including some 6x42, 8x50, 8x56, & 10x50 fixed power models.

Kahles scopes at CDNN

LWD

The 56mm will be slightly brighter to your eye than the 50mm.

Dave