Gun Optics: What Are Aberrations?

by
posted on June 27, 2017
spherical-aberration-disk.jpg
Any difference between the image of an object viewed through a riflescope and the ideal image of that object is called "aberration." Here are some of the more common types of aberration that you might hear about when optics are being discussed.

Chromatic aberration
This is a color flare or color fringe along the edges of objects in the image.

Spherical aberration
This occurs when light rays passing through the center of the lens do not focus at the same point as rays of light passing through the lens edges. The result is a low-contrast, soft-focus image.

Pincushion and barrel distortion
This is the tendency of straight lines to "bow in" or "bow out" from the center of the image to its edges.

Astigmatism
This is the inability to focus the image due to imperfections in the lens system.

Curvature of field
The image is not flat. Straight lines appear to be bent.

It is important to recognize that no optical system can be completely free of aberration. All optical systems are a design compromise that minimizes some types of aberration while necessarily allowing others. Many of the lens elements in a riflescope are included for the purpose of correcting various types of aberration.

Aberration is not simply the result of imperfect lens grinding or improper design; some types of aberration are basically inevitable, due to the fact that different wavelengths of light focus at different points. Also, some types of aberration result from the characteristics of spherical lenses (lenses whose curved surfaces are ground with an equal-radius curvature). Some forms of aberration can be eliminated by the use of aspherical lenses.

Latest

Taurus Raging Hunter
Taurus Raging Hunter

Launching 2023: Taurus Raging Hunter 10.5" in .460 S&W Magnum

If your big-game adventures take you into big-bear territory, here's the big-bore revolver to bring along.

Fun Friday: Old Sheriff's Favorite Dumb-Criminal Moments

Your average lawbreaker ain't exactly Professor Moriarty.

Launching 2023: Bergara B14 Wilderness Ridge Carbon Rifle

Bergara quality at a family-friendly price? Yes, please!

Throwback Thursday: History's Longest Duel

It started with an insult and glove-slap, but ended in "bromance."

Rising Shooting Stars: Morgan Leonhardt

She may not be old enough to drive, but this New Orleans phenom is racing to the top of the competitive shooting world!

7 Simple Follow-Through Tips to Improve Your Accuracy (Right Now!)

You've just finished squeezing the trigger, but hang on...you're not done yet.

Interests



Get the best of NRA Family delivered to your inbox.