Thread: Low light detail? – Binos vs scope

Originally Posted by uk_exile

Think is just my combo of mid-range Nikon scope and shitty unbranded binos. Have noticed in the last 30 mins before dark the detail I see in binos really falls off but it remains clear in scope until last few minutes. As expected being higher quality the scope is always clearer but difference shows much more as light level fades.
Is low light difference caused by 35 binos vs 42 diameter scope, or is it the superior scope glass quality, or is it a combo of size and quality?
It’s obvious regardless of scope zoom. When set at same 7x as binos the difference is really noticeable as light falls.
Scope is Nikon Monarch 5 3-15x40 ED SF and binos are unbranded 7x35.
Would similar value scope and binos perform similarly in low light? Or similar diameter necessary to perform similarly?

FYI I do plan to get better binos sometime however Mrs out of work (anxiety) so budget constrained and these binos were available for the right price, free.
If it’s simply the binos quality I’ll persist as is and use scope at last light with safety on & no ammo in chamber.
If it’s bino diameter I know when I do buy some in future to get bigger diameter, like 8x42 or 10x42.

Higher magnification requires thicker, denser lenses, so more weight, and a bit less brightness through the thicker glass.
Larger objective lenses mean larger lenses, so more weight.

Question one is, how old are you? If you are 50+, chance is your pupils won't be able to dilate much above 5mm diameter and so don't bother with super bright binos with large exit pupils.

You get the exit pupil by dividing the objective lens with the magnification. The exit pupil is the cylinder of light streaming back from the eyepiece.

i.e. 10x40 binos has a 40/10=4mm exit pupil, not optimal at dusk for anyone, but better at all other times than dusk due to the higher magnification.
8x40 binos have a 40/8=5mm exit pupil, optimal for a 50+ year old.
7x35 binos have a 35/7=5mm exit pupil, optimal for a 50+ year old.
6x30 binos have a 30/6=5mm exit pupil, optimal for a 50+ year old. Brighter image than 8x40s due to thinner glass required for 6x magnification.
7x50 binos have a 50/7=7.14mm exit pupil. Great at dusk for a 21 year old who can dilate his/her pupils that far, but not worth the extra weight for a 50+ year old.

Have a think what you need. If you are a dusk hunter, you are talking shorter distances anyway, so maybe bright low-magnification will be more suitable.

But as someone (not me) on this forum said, the best binos are the ones you have on you when you need them.