Light gathering scopes

Glass & coating quality. Some of my 40mm objective lens scopes are brighter & transmit more light than some of my 50mm objective lens scopes, both set at the same power. Generally, Leupold is a good deal.

Perceived brightness:
Perceived Brightness = cube root of realistic light gain

"Perceived brightness is the perception of target light thru the scope relative to the perception of the amount of target light with a single un-scoped eye. Perceived brightness is calculated as the cube root of light gain which is the basis for computer color space brightness scaling & is also the perceived brightness of a 5-degree target in the dark with a uniformly dark background."

Then it gets into stuff like the lumen gain difference between un-scoped & scoped eye light gain that reaches the eye pupil. Like if 1 lumen for un-scoped eye & 50 lumens for scoped eye (50 times more) the difference would appear to be 50**1/3 or 3.7 times as bright.

Low light performance:
"This calculation derives Low Light Performance as the average of light gain and resolution gain through magnification. as a measure of target image acuity gain in low light similar to Twilight performance specified by scope manufacturers. Low Light performance is much more useful than Twilight Performance as Twilight Performance is the average of just the objective lens diameter times magnification while Low Light performance is the average of the actual Perceived Brightness times magnification which includes the exit pupil/eye pupil relation, light transmission, approximated diffraction and perception of relative light gain. Resolution & contrast are not included. Lower quality optics will yield relatively less gains at higher magnifications."

My experiences are similar to tt35's. My Leupold 6.5-20X40 & 6.5-20X50 give good low light performance, better than comparable 20% lower priced Vortex scopes of similar magnification & objective size. No Razor's.

Imagine - dust covered rodents sitting on same color dirt in deep shade at 270 degrees (west) late afternoon. Next scope will be more spendy & brighter.

Elementary astronomy lession - never, ever look at the sun with your optic - it's that cube root stuff.
 
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tt35,

What is your procedure for testing?
Pretty simple. I spot a jackrabbit then switch to my rifle and see if I can see it well enough to shoot it. Of the scopes I've tried, the ATACR is the one I can shoot them the latest/ darkest. "Whether He is a sinner or not, I do not know. One thing I know: though I was blind, now I see."
 
tt35,
I use some 13" wide fork deer antlers 131 yards from the porch set in the woods. When I can not discern it well enough to call it legal I note the time.

The Swarovski z5 5-25X52, Leupold VX6 4-24X52, and the Bushnell 6500 4 1/2-30X50 went down in the same minute. The Leupold VX5 3-15X56 lasted six minutes longer. The Swarovski voice 2.7-18X56 lasted another fourteen minutes.

I had a Nightforce 12-42X56 that was way better than the first three, but didn't have the antlers set up when I still had it so I don't know how much better in minutes.
To whom much is given much is required.
 
WAAAAY more scientific than me! I just shoot and after a while it becomes apparent what's working. I must say that as content as I was with my NXS scopes, I was impressed on several fronts with the ATACRs. I've never taken the plunge on a SWARO rifle scope. (I run one of their spotters.) Maybe I should!
 
I don't know if anyone has already said it but there is no such thing as a light gathering optic. An optic just transmints some percentage of the light incident on the objective lens to the eyepiece. This amount is specified as transmisivity coupled with an exit pupil size. So for more apparent light at the eyepiece, look for high transmisivity values.
 
I don't know if anyone has already said it but there is no such thing as a light gathering optic. An optic just transmints some percentage of the light incident on the objective lens to the eyepiece. This amount is specified as transmisivity coupled with an exit pupil size. So for more apparent light at the eyepiece, look for high transmisivity values.

Now why did you bring that in? We trudge merily along using incorrect nomenclature and you bring this in. How are we ever going to cope??

I think I'm going to be triggered.
 
Don't get caught up in the marketing figures, percentages doesn't take into account sample variations and other factors. Either you can see to make a shot or you can't. Look for something with the largest apparent fov possible, you'll also want something that can maintain IQ at power, it's one reason bins appear better than scopes, more area is a huge thing when hunting 45-50 minutes after sunset. Swaro z6 and z8's, Zeiss v8's or the older diavari v series, the Leica magnus is also up there, a good sample of any will get you there. As a cheaper option the Steiner Predator 4 is outstanding, it outclasses anything remotely close in price imo. Again, either you can see or you can't, that's all that matters assuming we take into account the scope works of course.
 
Casscade,
My single experience with a z6 5-30X50 was terrible. I was not as good as the other scopes on the porch at the time. The owner sold it the next day.
 
Should have been more clear because the 2 high power scopes in that group have a smaller apparent fov for what ever reason than the 15x and under scopes, where as the z8s all have the same 24 degree field regardless of power.

Either way it still should have had good glass unless it was a dud which is more common these days it seems. I've noticed especially in the last few years I'm seeing more and more inconstant samples than past years with Zeiss, Schmidt, and swaro.

Not sure what's going on but when I have 2 of the same scopes and one is incredible and the other is a dud it makes it hard to buy blind without seeing first.
 
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I currently own 3 nfc 50 mm few Zeiss, few Leupold's. Was wondering the best light gathering scope to get me a few more minutes of shooting time. I was watching some deer this evening with my 10x42 swaro hd but my zeiss 4-14 44mm couldn't make out. I'm 63 and my eyes have changed was wondering the best out there.

Swarovski
 
Just gonna throw this out there.
I've spent some time with the new Steiner T6Xi. I have several high end optics to compare to. I haven't been this impressed with an optic for quite some time. Not just build, quality, glass, but the low light ability with the 2-5-15x50 is identical to my Swaro Z6i. Super impressed. Might be my favorite over all riflescope.
 

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