Astigmatism and Red Dot Optics

Does your dot look like the following:

SMEAR – COMET WITH TAIL – COMMA

It is unlikely the optic is faulty, but not impossible.

The most common reason is that some degree of astigmatism is creating this distortion, which affects 1 in 3 of the world's population and can vary with age.

This issue cannot be solved by purchasing a higher-grade red dot; whether it is a £50 Red Dot or £1,000 Red Dot, the result will be the same if you have astigmatism.

How to Check Your Optic

1. With the RDS held in your hand, slowly rotate it while keeping your head in the same position. If the distortion stays static and does not rotate, this is most likely due to astigmatism.
2. Use a camera or phone to take a picture of the dot. It should appear perfectly round.

Solutions

1. Live with it, as red dots are designed for quick target acquisition and not ultimate precision.
2. Focus at distance, not on the dot inside the optic. This can lessen the issue, as the dot is focused at infinity.
3. Ensure the brightness setting is appropriate for the light conditions. Too high a brightness can simulate astigmatism; the higher the brightness, the more the flaring will increase.
4. Use prescription glasses with astigmatism-correcting lenses.
5. Polarised glasses can help reduce the problem.
6. Use an aperture peep sight matched to the height of the RDS.
7. The use of a holographic sight (laser emitter rather than LED) could improve or worsen distortion, depending on the individual.
8. Alternatively, use a Prism 1x sight with an etched reticle. With these, there should be no astigmatism issues.