I was holding my scopes today, and I put one to each eye. I was trying to compare the crosshair thickness. One had a 4 inch eye relief and the other had a 3 inch eye relief. Besides going cross-eyed, I noticed that the sight picture in one was substantially larger than the other.
I generally assumed that longer eye relief was better because it is easier to mount on a rifle with a two piece base (you can only move it so far back before you run out of adjustment) and of course the whole recoil thing where the scope wont give you a black eye.
Anyway I am using these scopes for rimfire so recoil is not an issue. This is what I noticed: The scope with the shorter eye relief provided a larger image through the scope. This makes sense if you think about it (your hand in front of your face looks bigger than your hand outstretched in front of you).
Now since your eye has a finite number of rods and cones (receptor cells in the retina), would it be safe to assume that the shorter eye relief would allow you to resolve more detail (given equal quality optics, magnification, etc)?
Basically the way I came to this conclusion is I was trying to make a scope cam, and the camera is wide angle so when you line it up, only the center portion of the image captured is the view through the rifle scope (the rest is just a blurry image of the knobs, rifle action, and surroundings). When the same camera is used in a telescope (very short eye relief), nearly the entire image captured shows the view through the scope. Now of course it has a higher magnification, but the point is that more pixels are recording useful information. The pixels are like the cells in the retina for the previous example. If you compare two scopes with equal optics/magnification but with different eye relief, the one with the shorter eye relief is going to show you the same image spread across more cells in your retina, thus giving the image a higher resolution.
Does this make sense to any of you? Are there any flaws in my logic? The one thing I am wondering is if eye relief is a function of the optics (i.e. exit pupil is determined by objective diameter divided by magnification). Admittedly, the two scopes I compared were not the same magnification range or objective size. If eye relief is determined by some optical equation and cannot be "set" or manipulated to a desired value then I think this would blow my whole theory out of the water.
I generally assumed that longer eye relief was better because it is easier to mount on a rifle with a two piece base (you can only move it so far back before you run out of adjustment) and of course the whole recoil thing where the scope wont give you a black eye.
Anyway I am using these scopes for rimfire so recoil is not an issue. This is what I noticed: The scope with the shorter eye relief provided a larger image through the scope. This makes sense if you think about it (your hand in front of your face looks bigger than your hand outstretched in front of you).
Now since your eye has a finite number of rods and cones (receptor cells in the retina), would it be safe to assume that the shorter eye relief would allow you to resolve more detail (given equal quality optics, magnification, etc)?
Basically the way I came to this conclusion is I was trying to make a scope cam, and the camera is wide angle so when you line it up, only the center portion of the image captured is the view through the rifle scope (the rest is just a blurry image of the knobs, rifle action, and surroundings). When the same camera is used in a telescope (very short eye relief), nearly the entire image captured shows the view through the scope. Now of course it has a higher magnification, but the point is that more pixels are recording useful information. The pixels are like the cells in the retina for the previous example. If you compare two scopes with equal optics/magnification but with different eye relief, the one with the shorter eye relief is going to show you the same image spread across more cells in your retina, thus giving the image a higher resolution.
Does this make sense to any of you? Are there any flaws in my logic? The one thing I am wondering is if eye relief is a function of the optics (i.e. exit pupil is determined by objective diameter divided by magnification). Admittedly, the two scopes I compared were not the same magnification range or objective size. If eye relief is determined by some optical equation and cannot be "set" or manipulated to a desired value then I think this would blow my whole theory out of the water.
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