Vignetting is where the edges of a photo are darker or less saturated than the center. It can be caused optically by your equipment or added later when you edit your photo. Vignettes are a popular retro effect, so let’s explore them a little more.
A vignette can happen when you take your photo. There are a few main reasons for this:
Optical vignetting happens due to the design of the lens. Generally, the internal elements of the lens block some light that’s coming from the sides of the scene, reducing the amount of light that hits the edges of the sensor. It’s particularly common with wide-angle lenses and gets worse at wider apertures. The effect is a lot less pronounced with modern lenses, which is why it’s such a retro hallmark of film photography.
Mechanical vignetting occurs because some accessory that you’re using—typically a lens hood or filter—blocks some light from the edge of the scene from entering the camera. It can happen if you use the wrong lens hood or stack too many filters together. Again, this is more common with wide-angle lenses.
Pixel vignetting is a much smaller effect than the other kinds of vignetting and is often automatically compensated for by your camera, but it’s worth mentioning briefly. It occurs because light hits the pixels in the middle of the sensor more directly than those at the edges of the sensor, leading to a slight drop-off in brightness.
While vignettes can look cool, vignetting is normally seen as a problem. Optical vignetting is often corrected in post-production. Apps like Lightroom and CaptureOne have databases of how popular lenses render vignettes, so they can correct for them automatically.
Adding a Vignette in Post-Production
Most digital photos—especially those shot on smartphones—don’t have a noticeable vignette. So if you want to add one, you’ll need to turn to image-editing apps. It’s a good way to direct viewers toward the center of your image.
Many apps—including the iOS Photos app, Instagram, and VSCO—have a Vignette slider in their image editor. Open the photo that you want to add a vignette to, and then just drag the slider until you think that it looks good.
If you want a bit more control, turn to a fully featured image editor like Photoshop or Lightroom. Then, you can use a combination of adjustment layers and layer masks to selectively darken the edges of your image.