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40mm vs 50mm

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/06/2007 at 10:26
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How much more light transmission would get through a 4x12 50mm than a 4x12 40mm? 

 

From what I read your eye can only open to 7-8mm.  Is the extra exit pupil light wasted?

 

Would it be noticeable at dusk? 

 

What about the disavantages of a high scope mount of a 50mm vs 40mm. 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/06/2007 at 12:55
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The other thing you get with a larger objective is better resolution, picking up fine details.  Now, what you will find is the larger diamiter to be more forgiving at higher powers in lower light.  On lower quality scopes, you will see less differance. 

 

Scope mount 1/2 of 10 mm is 5mm or ~.20 inches higher.  That is less than a quarter of an inch. So now it is about stock fit ;)

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/08/2007 at 06:48
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The larger objective will allow you to use higher power setting in low light without exceeding the exit pupil size.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/08/2007 at 20:00
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Exit Pupil can be variable too. I fit 22yo with no medical history maybe able to utilize a 7mm exit pupil. A 47yo male will certainly not. Possibly only 5mm. There are a lot more variables as age progresses.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/09/2007 at 05:47
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Originally posted by tophet1 tophet1 wrote:

Exit Pupil can be variable too. I fit 22yo with no medical history maybe able to utilize a 7mm exit pupil. A 47yo male will certainly not. Possibly only 5mm. There are a lot more variables as age progresses.


Agreed, its actually a continually changing equation as far as human ability to achieve pupil dilation. The unchanging part is the optics end as shown in the chart above. No matter what your eye pupil is capable of though....... the larger objective will still always allow more magnification to be used by a given user. Magnification doesn't increase brightness........but.........it brings the object closer all other things equal and allows it to be seen better. You can have your eye doctor check your eyes dilation ability at your next check-up, you might be surprised how large a middle aged eye can still dilate in some people.

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/03/2007 at 13:57
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As a 56 year old male, I can tell you that I have a hard time keeping my pupil lined up with an exit pupil of the same size.

The other issue is focal range.
I got a VX3 6.5x20x40 side focus and a VX3 6.5x20x50 with side focus
The 40mm can just barely focus at infinity with 6.5X and just barely focus at 50 yards with 20X.
The 50mm OTOH, can focus way closer than 50 yards at 20X.

I have an old VARI-X-III 6.5x20x40 boosted to 13x40x40 with focus on the objective bell that has no trouble focusing up close at high power.

In varminting I am constantly changing the power and the focus. The side focus is easer to reach, but has some design compromise in the VX3 40mm.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/04/2007 at 12:02
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If my math is not to far off today I think the 50mm objective has about 25% more area for light to hit than the 40mm objective so it starts with more light but after this all kinds of variables enter into things coating etc. Easy test take both outside and look through both scopes and do a subjective comparison which you lke best. Brighter is not always clearer or as good of resolution.

 

Duce 

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