Long eye relief scopes in low light
Question: Are long eye relief scopes (say, in the Styer scout configuration) harder than normal scopes to use in low light conditions?
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Gonna depend on the diameter of your pupil and the objective lens of the scope. The objective (in 2x32 its the 32) divided by the magnification gives the diameter of the image at focal length. Thats why on a higher powered scope (say a 3-9x40 at 9x) you get a small circle image until you crawl the stock a tad... 0 -
Well, assuming you have a 2-7x32. Once you settle in to the focal point, will it be difficult to use in low light? It was my understanding that the wider the field, etc, the more light it gathers, correct? 0 -
Yes, this is why the Scout Rifle concept, tried by the Germans during WWII with the Zf41 configuration, failed then and will fail now.
Too much distance between your eye and the lens.0 -
quote:It was my understanding that the wider the field, etc, the more light it gathers, correct?
Incorrect. The objective of any lens does not "gather" light. All a scope does is transmit light, and naturally it does so imperfectly. The very top rated scopes transmit no more than 96-97% of the light that strikes the objective lens. Now that is pretty good, but you simply cannot force more light through a scope by making the objective bigger and bigger. Take the diameter of the scopes objective lens, say 40mm. Divide that by the magnification of the scope, say 4x and you get a 10mm exit pupil. That is the little circle of light you see in the ocular lens of the scope when you back off past the focal point. At the focal point that circle will appear to fill the ocular. Roll the magnification up to 8x and the exit pupil drops to 5mm. See how that works? Your pupil can dilate to about 7mm. That is if you are young and have good eyes. For us older guys, it is less, maybe 5mm, 6 if we are lucky. Thus an exit pupil larger than your dilated pupil is simply transmitting light your eye cannot use. An exit pupil larger than about 6 or 7mm means you are using a scope with an unecessarily large objective, you are at the low end of a variable scope, or you are planning to hunt at night in Europe. Push that scope up to the scout rifle position and you will certainly have more trouble in low light situations. I concur with P3Skyking.0
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