Aperture vs Rx
Posted: Wed Apr 27, 2011 10:51 pm
How useful is an aperture for seeing the front sight? Compare with a good Rx lens. Is there a matter of degree of sight impairment?
An aperature isn't so much about replacing a prescription lens as it is intended to increase depth of field. Increased depth of field means you are better able to see the rear sight in 'apparent focus' (it's not true focus, as spelled out in great detail in many a treatise on photography), reducing the vagueness of the blurred gaps between front and rear sights. In very bright light one's eyes tend to do the same sort of thing, as the eye naturally shrinks its iris. An artificial iris gives the shooter control, especially with the variable aperature types, of this depth of field improvement in variable lighting conditions.
Whether or not you use an iris for shooting, it is best to be able to bring the front sight into crisp focus regardless of lighting conditions. If your eye is unable to do this easily, then you should seek a corrective lens to make it so. After that would be the time to consider an iris to then bring the rear sight into a less blurry condition, if this is a problem for your eye that is.