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 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.

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.

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.

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.

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.

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.

Rayleigh rangecalculator

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.

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.

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.).

Rayleighdistance far-field

M2 = Beam quality (laser-dependent) k = Correction factor, depends on A and D (ideally 1.27; more typically between 1.5 and 2.0) A = Aperture of the scan system D = Beam diameter prior to focusing (typically 6 – 70 mm) λ = Wavelength (typically 193 nm – 10.6 μm) f = Focal length (typically 30 mm – 2,000 mm)

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.

Rayleighlength numerical aperture

By transforming lasers into universal tools, scanning solutions help to add functionality and value to materials. SCANLAB's broad palette of scanning solutions fulfills demands for higher speed, more precision, greater efficiency or improved environmental compatibility.

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.

Beam waist formula

Rayleigh rangeGaussian beam

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.

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

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!

Gaussian beamRayleigh rangecalculator

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.

Beam waist

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.

Beam waist calculator

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.

Here you'll find explanations and definitions of key technical terms from the fields of optics, scanner technology, laser technology and laser processing.

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.

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.

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.

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.

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.

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.