Home Forums Hunting & Shooting Hunting Optics 40mm vs 50mm? same scope. will I notice the difference?

the 2.5-10x42 zeiss will take you way past legal conditions and works well under moonlight

I won't own a 50mm scope,because I don't like having to mount them that high.I also don't like a 50mm scope fits in a scabbard for horseback hunts.

I see alot of used "x50" scopes for sale here. I suspect that a lot of these sellers are younger, new shooters that like the way they look and the new scope is purchased with that in mind. They soon find that they are better of with a smaller, lower positioned scope of better quality.

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SuperCub,

Do you happen to know the mounting height difference between a 40mm scope and a 50mm scope in fractions of an inch?

I am real curious.

I agree with Alaska Cub. The difference is in the exit pupil. This has a direct affect on twilight performance.
The Zeiss website has a brief read on this in their little online optics school. http://www.zeiss.com/C1256BCF0020BE5F?

The larger the objective lense is the larger the exit pupil. If the exit on the 40mm is larger than your eye pupil then the even larger exit pupil will not add much but on the higher powers it will allow more light to reach your eye and make it apppear brighter.

Here is the math on 20 power.
40mm / 20 power = 2mm
50mm / 20 power = 2.5mm
In very low lighting that .5mm is noticable. Could make a 10 minute of usable daylight difference. That's when it counts the most.
Turn the power down and it gets less important as they are bigger than your own pupil.
40/9=4.44mm
50/9=5.55mm

This is why on the lower powers most will say it makes no difference. The extra light can't be used by your eye though I will say it is more comfortable to use a scope with a very large exit pupil.

I don't know. I don't use either for hunting rifles. All my scopes are either 2x7, 2.5x8 or straight tube.

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SC and Ringman,
I just went through the mounting height deal with a couple of recent scope installs. The difference between a medium ring height and a high ring height in a Leupold ring is .770" to .900" or .130 if memory serves me correctly. On some rifles a set of low rings may work with a 40MM scope. Not sure what the low ring height differnece is but am guessing at another .130" or so. The O.D. difference is around .400" (10MM)making it roughly .200" in increased ring height depending on the brand of scope. I have found that going from a low to a medium or a medium to a high will get a guy from 40MM to 50MM in scope objective size on the same rifle. Hope this is what you were looking for.

Dave