Absolutely! They’ll make your lens lighter, your images sharper, and bring aberrations and distortion down to near zero. The only downside is how much they cost.

Catadioptric lenses have relatively low contrast, quite acceptable for astronomy but a severe drawback for general photography. In addition, out-of-focus highlights will appear as doughnut shapes, distinctive and not always pleasing.

Dobsonian telescope

The aspherical glass lenses used in top-of-the-line telephoto and wide-angle lenses are particularly expensive. They’re usually ground and polished by hand.

Designers – especially with wide-angle lenses – often have to stop-down their optical systems to exclude the corners so as to avoid an excess of field curvature.

RC Telescope

Learn about the benefits of aspherical lenses (Asph Lens) in photography and why you should (or shouldn't) attach one to your camera in 2023.

3. An aspherical lens element has much more precise control of how light travels inside your lens. So much so, that one asphere can oftentimes negate the need for many of the standard lens elements that would otherwise be needed to achieve the same effect.

They also allow manufacturers to create smaller and lighter lenses since they reduce the need for numerous lens elements and lens groups.

Telescope type

In the past, only pros could afford such top-of-the-line optics. These days they’re still spendy, but at least they’re not completely the ballpark for ordinary photographers.

Aspherical lenses are used primarily in high-end optics to create sharper images and reduce or eliminate certain optical imperfections (i.e. chromatic aberrations, field curvature, etc.).

Ideally, light rays, when passing through a camera lens element, would all converge at a single point thereby creating a sharp focus. Unfortunately, this isn’t the case with many spherical lenses.

An aspherical lens is simply a lens that doesn’t have a spherical surface shape. Instead, it has an aspheric surface (i.e. non-spherical), usually with counter-curves near its edges.

Relatively small size and light weight are the main advantages for a photographer. The catadioptric design provides a very high degree of optical correction, making such lenses popular for astronomy.

Cassegrain telescope

Maybe you’re looking at buying a new lens and aren’t sure if you should fork out the extra cash for the one marked “Asph Lens,” or you’re just wondering what makes aspheric lenses expensive.

Spherical aberrations occur when incoming light rays pass through a spherical lens and focus at different points, causing blurry images and reducing overall image quality.

Fresnellens

Aspherical lenses are curved outwards on their rear element so that they can better direct light rays into a single focal point. These counter-curves help correct spherical aberration, creating sharper images.

Teryani Riggs (they/them) is an adventure, who loves all things wild and free. Teryani can often be found in the midst of a social/eco-justice campaign, hiking through wild backcountry, or hitchhiking around the world listening to other people’s stories. While their focus has historically centered on landscape, travel, and wilderness photography, they’ve also been hired to shoot genres as varied as historical fiction reenactments in the studio to product and food photography.

Chromatic aberration

Learn about the benefits of aspherical lenses (Asph Lens) in photography and why you should (or shouldn't) attach one to your camera in 2023.

As you can imagine, aspherical lenses aren’t just used in cameras. They’re a vital part of any system that needs a high standard of optical quality, from telescopes and contact lenses, to rifle sights and missile-guidance systems.

Of course, asph lenses are considerably more expensive than spherical lenses, but high-quality glass will last a lifetime, so if you can spring for the high-performing lens, go for it!

These counter-curves direct light rays hitting the edges of a lens to converge at the same point of focus as the light rays hitting the center.

Catadioptric

One way to compensate for this is by using a combination of concave and convex lens elements. Another way is by using an aspheric lens.

The optical design precludes fitting a diaphragm and the aperture of these lenses is always fixed. Light adjustment can only be by use of neutral density filters giving no control over depth-of-field, which is always minimal.

It’s really amazing how far modern optics have come. Not too long ago, only pros could afford full-frame cameras and aspherical lenses. Now those of us in the prosumer world can get them too.

Standard lenses use spherical elements, many of which aren’t natively able to direct the light reaching its edges to the same focal point as the light reaching its center.

Either way, knowing what an aspherical lens is and what it does will help you in better understanding your gear and when it comes time to purchase new types of camera lenses, you’ll have a better idea of what to buy.

1. Physically, spherical lenses have a front surface that is spherical, meaning the curve is the same from top to bottom and left to right – like a portion of a sphere.

Optolens

The lens surface of an aspherical lens corrects for this, making it possible to shoot at wider apertures and allowing us to use the entire surface of the lens.

The short broad shape of a catadioptric lens is very distinctive, as is the back of the secondary mirror visible at the front of the lens. Light is reflected by the primary mirror at the rear of the lens onto the much smaller secondary mirror and from it through conventional optics onto the film or sensor. This double folding of the light path makes the lens very short for its focal length. The large primary mirror provides most of the magnification.

Mirror lenses, or catadioptric lenses, combine curved mirrors (catoptrics) with glass lens elements (dioptrics). Used only for telephoto lenses, the design provides a much shorter, lighter, and less expensive lens than a comparable conventional telephoto lens.