Q: I have an El Cheapo Chinese scope that is impossible to shoot accurately with. My gunsmith says it is full of parallax. Can you tell me what parallax is and how I can rid my scope of it?
A: In hunting scopes of low quality, there are a number of sources of parallax. If the reticle is not mounted precisely at the correct distance back of the objective lens the point of “no parallax” may not be at any normal shooting distances, with errors at all distances exaggerated. Reticles which are loosely mounted can move backward or forward within their mounts, and even a few thousandths of an inch will introduce changing amounts of parallax. Also, parallax can be introduced by optical deficiences in the objective – either in thedesign or manufacture. If spherical aberration or astigmatism have not been adequately corrected, images may form a considerable distance from the reticle. El Cheapo scopes may show apparent movement of the reticle as compared with the background which is different when you move your eye up and down than when you move it from side to side. This is because of a poor objective. No adjustment of the scope will eliminate these faults of optical deficiencies.
These days there are a number of good reliable scopes selling for around $500 to $600, anything cheaper than this is not likely to be much of a bargain.