simple eyebox question

If I have two scopes and I am looking across a field at dusk.

scope A is lets say a 2.5-10x56

scope B is lets say a 5-25x56

lets say they are the same brand and glass quality is equal.

If both scopes are set to 10 power.......will scope A be harder to get a perfect image since its magnification range is maxed out?

or will the image quality be the same on both?

Thanks

Yes.

In my somewhat extensive experience, I've never seen a difference but frankly have never compared scopes side to side for that particular test.

I DO however feel that a 56mm objective is unnecessary in a scope that only has 10x as it's maximum magnification and with good quality coated glass I think anything beyond 40mm is just adding to weight and size with no measurable advantage and that opinion comes from having a several scopes with big objectives and several with 40mm objectives with no observable clarity or brightness until you get above about 20x.

Quality of glass and coatings in a scope trumps size every time.

nwmnbowhunter said:

Yes.

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X2!

Exit pupil size should be the same in both. Right?

Philward said:

Exit pupil size should be the same in both. Right?

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The spec sheet should tell you that.

I've done a similar comparison with scopes with smaller objectives and to my eye, the image quality was the same.

Philward said:

Exit pupil size should be the same in both. Right?

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Yes, Exit pupil = Objective lens size / Magnification. In this scenario 56mm/10 = 5.6mm exit pupil for both scopes at 10x.

LDHunter said:

In my somewhat extensive experience, I've never seen a difference but frankly have never compared scopes side to side for that particular test.

I DO however feel that a 56mm objective is unnecessary in a scope that only has 10x as it's maximum magnification and with good quality coated glass I think anything beyond 40mm is just adding to weight and size with no measurable advantage and that opinion comes from having a several scopes with big objectives and several with 40mm objectives with no observable clarity or brightness until you get above about 20x.

Quality of glass and coatings in a scope trumps size every time.

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The exit pupil size should match the amount of dilation of the eye's pupil, approximately 4mm in daylight and 5-7mm when it's fully dark-adapted. A 40mm objective on a 10x scope gives a 4mm exit pupil, a 56mm objective on the same 10x scope gives a 5.6mm exit pupil. The larger the exit pupil, the larger the eye box and the less precise your eye has to be aligned with scope, allowing for quicker target acquisition.

An exit pupil smaller than your eye's pupil dilation will restrict the light entering your eye, making the image darker and the eye-to-scope alignment much more critical. Increasing the exit pupil beyond the diameter of your eye's dilated pupil will have no effect on the image quality (all else being equal) because your eye's pupil diameter becomes the limiting factor, it does however affect the eye box and provides a larger area for your eye to move around in and still collect the maximum amount of light from the image.

Elkwonder said:

If I have two scopes and I am looking across a field at dusk.

scope A is lets say a 2.5-10x56

scope B is lets say a 5-25x56

lets say they are the same brand and glass quality is equal.

If both scopes are set to 10 power.......will scope A be harder to get a perfect image since its magnification range is maxed out?

or will the image quality be the same on both?

Thanks

Click to expand...

All things equal, eyebox will be better on scope B. Depth of field will probably better on scope B, too but no guarantees there.

I think you are onto something, but optical design can be a deep subject.

For starters, how does the field of view compare between scope A and scope B at 10x? ... no guarantees that's equal either!

I dont know why, but guns and ammo seem so straight forward and are easy to understand if you are willing to dig in and do the research. However scopes.........oh lawdy! It seems the more I dig in, the more confused I become. I dont think I have ever wanted to just buy something and call it a day to be done. It seems the more I dig in, the farther I am away from making a decision. lol

There are many things to consider but the OP's question was about "image quality".....

You can talk science til you're blue in the face but huge objectives on scopes without a pretty high magnification range are mostly a waste. If you're gonna spend that kind of money you're better off getting something like a 3-15x56 or even better a 4-24x56 at least.

I frankly don't see the point in a huge objective lens on a scope with 10 power on the high end. You can talk exit pupil all day long but in the real world it's a waste of all that size and expense if you don't match it with a higher magnification.

Consider this... a 4.5-14x40 scope has been one of Leupold's best sellers in history and I never heard anyone complaining about needing a way bigger objective lens.

I've had Bushnell Elite 4200 scopes that were 6-24x40 and the clarity and brightness were astounding even at the highest power. The lens glass and coating on the Bushnell scopes is very hard to match but sadly their erector assemblies left me wanting more. Yes they would have benefited from a bigger objective but it wasn't nearly as important as the quality of the glass and lens coating.

Science is wonderful but in the real world stacking scopes will teach you some very valuable lessons and I've done it several times and people are usually in disbelief when all that internet jargon is not visible in the field and some of the big name optics companies with huge price tags get shamed.

Elkwonder said:

It seems the more I dig in, the farther I am away from making a decision. lol

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Optics are so personal, and there is no 'perfect' scope, haha, I get it for sure;

Jump in! If you are careful and buy used you'll be able to get your money back when it comes time to sell.

Hunt for a season, find your own preferences.

Like a vehicle, a test ride is going to tell you a lot more than a spec sheet

I wish NF would introduce a NX6. 3-18 X 50. That would be perfect in my opinion.