Light Transmission

[swpc629]

I may have ask this question before, but my ADHD seems to have taken over. Does objective and tube size effect light transmission? Or is it just a matter of how the lenses are coated?

 

[theo98]

I may have ask this question before, but my ADHD seems to have taken over. Does objective and tube size effect light transmission? Or is it just a matter of how the lenses are coated?

Larger objective sizes pull in more light and lens coatings enhance colors (such as game) that all but disappear at twilight.

Larger tubes can offer greater mil-moa turret adjustments for long range shooting and create a more rigid scope body...however at the expense of added weight.

 

[Sully2]

All of the above!

 

[bruce_ventura]

We'll sort of. What really matters is exit pupil size. Exit pupil = objective diameter / magnification. If the exit pupil is larger than your eye pupil, the image is as bright as it's ever going to get with that scope. If the exit pupil is smaller than the eye pupil, the image has lower brightness by a factor of (exit pupil/eye pupil)squared. This ends up being a bigger effect than the typically small differences in anti-reflection coatings, especially when comparing scopes at a similar price point.

FYI, dark adapted eyes have an exit pupil of about 5 mm (older people) to 8mm (younger people).

 

[lloydsmale]

for low light performance in order of importance in my opinion is first lense quality and coatings, second objective size and tube size means nothing

We'll sort of. What really matters is exit pupil size. Exit pupil = objective diameter / magnification. If the exit pupil is larger than your eye pupil, the image is as bright as it's ever going to get with that scope. If the exit pupil is smaller than the eye pupil, the image has lower brightness by a factor of (exit pupil/eye pupil)squared. This ends up being a bigger effect than the typically small differences in anti-reflection coatings, especially when comparing scopes at a similar price point.

FYI, dark adapted eyes have an exit pupil of about 5 mm (older people) to 8mm (younger people).