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Backyard Marksmanship
| REVIEW: Copperhead reflex sight |
fluzwup (M/oklahoma) |
9/6/00 9:09 pm |
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When I purchased my Crosman 1008, it came
packaged with a cheap red dot, or reflex sight. These
sights sell for about $10-20 in the US, and are the low
end of the reflex sight line. The Copperhead reflex sight is a tube sight, with an integral 3/8" mount (which should also handle 11mm rails). It is battery operated, with two dot intensities. The effective lens diameter is 17mm. Elevation and windage are adjusted by two screws which rotate the scope body relative to the mount, so as long as you don't bend or break the plastic, it should keep working. There is a small amount of wobble in the scope, but that's not going to be of any consequence. The battery is a CR2032, a common 3v lithium battery often used in calculators. Battery life is in excess of 24 hours of continuous use, since I've left it on overnight at least once. The low power setting is good for shooting indoors or on overcast days outside, while the high setting will handle even noon in the summer. Now remember that theory about the dot being focused at infinity? Well, that's only if you're using perfectly parabolically ground lenses of the right section, and have the reticle located exactly at the focal plane of the lens. Since life ain't perfect, you end up with lenses that are spherical, reticles that are slightly off the focal plane, and mirrors or lenses at wrong angles. This results in parallax errors and dots that focus at less than infinity. For comparison, I tested my Tasco ProPoint II red dot scope (about $100 in the US) at 2, 5, and 10 meters and tried to measure the parallax. I clamped the scope in a vise, aimed it at a grid at the given distances, centered the dot, and watched how much it moved as I moved my head so the dot moved from one side of the scope to the other. Measuring the distance the dot moved across the grid gives me the parallax error at each distnace. The distance to the target was measured from the front optic, and the eye relief in both cases was 24", also from the front optic. Here's what I found: Tasco PDP II 30mm reflext sight, parallax error, in inches: 2m: Approx .25" in all directions 5m: No discernable error 10m: No discernable error Now, the same test with the Copperhead 17mm reflex sight: 2m: Approx .25" down, .5" left, right, and up 5m: Approx .5" down, 1" left, right, and up 10m: Approx 1" in all directions Keep in mind that the error in the Tasco was the result of nearly 15mm of eye movement, while the error in the Copperhead was the result of 8mm of eye movement. Now this doesn't mean that the Copperhead sight is inaccurate, it just means that for it to be accurate, you need to get the dot centered in the lens. The Tasco's lack of noticable parallax effects just means that the dot doesn't have to be centered at those ranges, so you can fire the shot a little faster. � |
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