Vignetting

Vignetting is the darkening of a photo toward its corners and edges compared with its center. Every lens does it to some degree, it is strongest on wide and fast lenses used wide open, and it can be a flaw you correct or a tool that pulls the eye toward your subject.

The useful thing to know is that “dark corners” has at least three different causes, and each one answers differently when you stop down, change lenses or edit. Once you can tell which cause you are looking at, you know whether to change your aperture, take off a filter, tick a box in your editor, or leave it alone because it helps the picture.

What vignetting looks like and how big it is

Vignetting is measured in stops, the same unit as exposure. A corner that is one stop darker than the center received half as much light; two stops is a quarter; three stops is an eighth. In practice:

• Under about half a stop is hard to see in most scenes. It shows up only in flat, even subjects such as a clear sky, a white wall or a snowfield.
• About one stop is visible in a sky or plain background as a gentle shading toward the corners.
• Two to three stops, common on fast lenses at their widest aperture, gives obviously dark corners that most people notice at a glance.

Optical vignetting is a smooth gradient that starts somewhere between the center and the edge and deepens toward the corners. A hard-edged dark shape in the corner is a different thing, covered under mechanical vignetting below.

The three causes of dark corners

Natural vignetting: the geometry of wide angles

Light reaching the corner of the frame arrives at an angle, and that alone costs brightness, even in a perfect lens with nothing blocking the light. In a simple, idealized lens the corner gets cos⁴ of that angle compared with the center, which is why it is often called cos⁴ (cosine fourth) falloff. The angle depends on the focal length and the sensor size, so wide lenses suffer most.

Stopping down does nothing to natural vignetting. It is set by the angle of the light, not by the size of the aperture, so a 14 mm lens at f/8 still has dark corners.

The numbers behind the chart, with the corner angle measured from the center of the lens to the sensor corner (half-diagonal 21.6 mm on full frame, about 14.1 mm on APS-C):

Lens designers fight this with large rear elements and designs that bend the light so it meets the sensor at a gentler angle, which is why a real 14 mm lens does much better than 9%. But the trend in the table holds for every lens: the wider the view, the more the corners fall off. It is also why a full-frame lens on a crop sensor shows less vignetting. The smaller sensor sits in the middle of the lens’s image circle and never sees the darkest part.

Optical vignetting: the lens barrel shading its own light

Look into the front of a lens from straight ahead and you see a full, round aperture. Look at it from an angle and part of the opening is hidden behind the lens’s own rim and rear elements, so it looks like a cat’s eye or a lemon. Light heading for the corners of the frame sees that smaller opening, so the corners get less light. This is optical vignetting, and it is the big one on fast lenses: one to three stops at the corners wide open is normal.

Stopping down cures most of it. As the aperture shrinks, the off-axis beam is no longer clipped by the barrel, and the corners catch up. Most lenses lose nearly all of their optical vignetting by about two to three stops down from wide open, which on an f/1.8 lens means around f/4 to f/5.6. Whatever is left after that is mostly natural falloff, which stopping down cannot touch. See stopping down for what else changes when you do it.

You can see the same clipping in out-of-focus highlights. Background lights near the middle of a wide-open photo are round; near the corners they turn into cat’s-eye shapes, because each one is a picture of that clipped, lemon-shaped opening. Cat’s-eye bokeh and optical vignetting are the same thing seen two ways, and both go away as you stop down.

Mechanical vignetting: something in the way

Mechanical vignetting happens when something physical blocks the corners of the picture: a lens hood made for a longer focal length, a stack of filters, a thick filter ring, a step-up ring, or an adapter on a lens that was not made for the camera. It shows up as dark, fairly hard-edged shapes in the corners, sometimes with the outline of the ring visible, and sometimes black.

It behaves the opposite way to optical vignetting when you stop down: the dark shape stays and its edge gets sharper, because a smaller aperture renders the obstruction more crisply. On a zoom it usually appears only at the widest end and vanishes a few millimetres longer. The fix is physical: remove the extra filter, use a slim one on wide lenses, or fit the correct hood. A hood that is twisted slightly out of its bayonet position gives the classic sign, dark petals in two corners but not the other two.

Pixel vignetting: the sensor’s share

Digital sensors add a small amount of their own. Each pixel sits at the bottom of a tiny well, and light arriving at a steep angle near the edge of the sensor is collected less efficiently than light arriving straight on. Sensor makers tilt and shift the microlenses over the edge pixels to compensate, and cameras correct what remains. You rarely need to think about it, except that it is one reason a lens adapted from another system can show more falloff on a digital body than it did on film.

Which cause is it? A quick diagnosis

Shoot the same plain scene at your lens’s widest aperture and again at f/8 and f/16, with in-camera lens corrections off or in raw, and compare the corners.

Most wide-open falloff is a mix of optical and natural. The f/8 frame shows you how much is natural, and the difference between it and the wide-open frame is the optical part.

Seeing other faults in the same test shots, such as soft corners or uneven sharpness? How to test a lens walks through a full check, including how to spot a decentred lens.

Correcting vignetting in camera and in editing

Most cameras correct vignetting in their JPEGs automatically using a profile of the attached lens, and many raw converters apply the same profile by default. So a photo that looks evenly lit may have had its corners brightened by two stops or more before you ever saw it. Some modern lenses are designed with that correction in mind and would look much darker without it.

In an editor you have two ways to fix it:

• Profile correction. Turn on the lens profile and the software applies a falloff map measured for that lens at that focal length and aperture. This is the quickest and most accurate fix. The lens corrections page covers it alongside distortion and color fringing.
• Manual correction. A vignette amount control brightens or darkens the corners, and a midpoint control sets how far toward the center the change reaches. Use it when there is no profile, for adapted or old lenses, or to fine-tune.

Correction is not free. Brightening a corner by two stops amplifies everything in it, including noise, just as raising the ISO two stops would. In a bright daytime shot you will never notice. In a night sky shot at 14 mm and f/1.8, fully corrected corners can be visibly grainier than the middle, which is why many astrophotographers correct only part of the falloff.

Shooting stars with a fast wide lens and fighting dark, noisy corners? How to photograph stars and the Milky Way covers the trade-off between opening up and keeping the corners clean.

Using vignetting on purpose

The eye goes to the brightest part of a picture first and tends to stay inside the frame when the edges are darker. A gentle vignette uses that: darker edges hold attention on a subject in the middle and stop a bright corner from pulling the eye out. Printers have done it for over a century by burning in the edges of a print in the darkroom, and many photographs you admire have it without you noticing.

Some things to know when you add one:

• Use a post-crop vignette, not the lens correction control. Editors usually offer a separate vignette effect that follows your crop. The lens correction control is centered on the original frame, so after a crop its darkening lands off-center.
• Keep it below the level where people notice it. A good test is to toggle it off: if the picture suddenly looks flat and the eye wanders, it was doing its job; if you could see it before you toggled, it is too strong.
• Use feathering. A soft, wide transition reads as light. A narrow, hard one reads as an oval drawn on the picture.
• A vignette can be light as well as dark. A white vignette suits high-key subjects such as snow or a pale portrait background.
• It does not have to be centered. A radial or brush adjustment can darken just the side that competes with the subject.

Heavy, obvious dark ovals are the look of one-click filters and toy cameras. That can be the point, as in a deliberately vintage look, but used by default it makes a photo look edited rather than seen. Overdone vignettes are one of the signs listed under over-editing.

Would rather guide the eye with light while you shoot, instead of in editing? Photography lighting covers how to place light so the subject is the brightest thing in the frame.

Common mistakes and misconceptions about vignetting

• “Stopping down always gets rid of it.” It removes optical vignetting, not natural falloff. A wide lens keeps some darkening at every aperture.
• “Dark corners mean a bad lens.” Fast primes, often the most expensive lenses, vignette most when wide open. It is a trade-off designers make for size, weight and a wide aperture, then fix with a correction profile.
• “My filter is fine because it fits the thread.” On a wide lens, a thick polarizer or a stack of two filters can put its rim into the corners. Check the corners at the widest focal length and at f/11, where it shows most clearly.
• Using a hood from a longer or crop-sensor lens. A hood is shaped for one angle of view. On a wider lens it cuts into the corners.
• Calling an uneven polarized sky vignetting. A polarizer on a wide lens often makes one part of the sky much darker than another. That band follows the sun’s position, not the frame’s corners, and stopping down or correcting the lens will not fix it.
• Forgetting the profile is already on. Adding a manual correction on top of an automatic profile overcorrects, giving corners brighter than the center.
• Stacking a creative vignette on uncorrected falloff. Correct the lens first, then add the vignette you want, so you control how strong it is.
• Stitching panoramas with uncorrected frames. Each frame’s dark corners repeat across the result as dark bands in the sky. Apply the lens profile to every frame before you stitch.

Want to check you can tell vignetting apart from the other flaws a lens can show? The Lens Aberrations Quiz asks about vignetting alongside chromatic aberration, distortion and diffraction.

Try this: measure your own lens in 10 minutes

1. Find a plain, evenly lit subject: a clear or evenly overcast sky away from the sun, or a white wall in shade. Fill the frame with it.
2. Set the camera to raw (or turn off in-camera vignetting correction), manual focus, and focus as close as the lens allows so any texture blurs away.
3. In aperture priority, take one frame at each full stop from wide open to f/16. If you have a zoom, do it at its widest and longest settings.
4. Repeat the widest-aperture frame with your usual filter and hood fitted.
5. Open the frames side by side in your editor with lens corrections off. Read the brightness of the center and of a corner with the editor’s color readout, or simply look.

How to judge it: the aperture where the corners stop getting brighter is where optical vignetting ends, and the darkening left at f/16 is the natural falloff of that focal length. If the filter or hood frame has hard dark corners the plain frame did not, that accessory is causing mechanical vignetting. Finally, turn the lens profile on and see how much brighter the corners get; that is how much correction your camera has been quietly doing.

Not sure what “a stop” of difference means in exposure terms? Understanding f-stops in photography shows how each stop halves or doubles the light, which is the same scale vignetting is measured on.

Vignetting questions

Does vignetting get worse on full frame than on a crop sensor?

With the same lens, yes. A full-frame sensor reaches further out into the lens’s image circle, where both natural and optical falloff are stronger. A lens designed only for crop sensors has a smaller image circle, so on its own body it can vignette as much as a full-frame lens does on full frame. See full frame vs crop sensor for the other differences.

Should I always turn on vignetting correction?

For most daytime photos, yes; it is accurate and you lose nothing visible. For night skies or high ISO shots, a partial correction often looks better, because full correction raises the noise in the corners. If you like the way the falloff frames your subject, leaving some of it is a legitimate choice.

Why do my phone photos never seem to vignette?

Phone lenses are wide and do vignette, but the phone corrects every shot automatically. The darkening is still being undone in software, which is part of why corners of low-light phone photos are often noisier than the middle.

Can a lens hood cause vignetting?

The correct hood, properly seated, does not; it is cut to the lens’s angle of view. A hood made for a longer lens or for a crop-sensor lens, or one twisted out of position, will put dark shapes in the corners.

Is vignetting the same as light falloff from a flash?

No. Vignetting is the lens and camera darkening the edges of the frame whatever the subject. Flash falloff is the light itself getting weaker with distance, so it darkens whatever is further from the flash, which may be the center of the frame. The two can look similar in a photo but have different fixes.

Seeing other lens flaws alongside the dark corners, such as bending lines? Lens distortion explains barrel and pincushion distortion, which the same lens profile usually corrects.