6 common camera lens problems – and how to fix them
Some of the most common digital camera lens problems can be solved with a bit of know-how. Here’s a list of the best lens fixes, from chromatic aberration to vignetting
Camera lenses don’t always perform flawlessly. By understanding when they’re likely to let you down, and knowing how to take corrective action when taking the picture, or in software later, you’ll get results that meet your expectations. And don’t forget that lens problems can also be embraced as creative solutions in their own right…
LENS PROBLEM 1… Lens flare
Include a bright light source in the frame or allow stray light to glance across the front element and you’ll end up with pictures that have a ghostly, contrast-reducing sheen to them. You may also notice polygonal bright spots in the viewfinder, which can be distracting in the final shot.
To get the best from your camera lenses, keep the front element spotless and fit a lens hood. If you don’t have one, or it’s not deep enough to be of use, hold your hand or a piece of card out of shot just to the side of the end of the lens to shield it from the unwanted glare.
Before: ghosting and flare are obvious in this shot of a photographer…
After: by shifting position slightly and shielding the front element from the sun, both are removed.
This is characterised by a darkening of the corners of the frame, and is caused by the lens actually capturing its own sides. It’s particularly noticeable when you’re shooting a clear sky. The problem is usually associated with wide-angle lenses at wide apertures, although it only becomes a concern when you’re shooting on a full-frame camera, which makes use of the full diameter of the lens. Vignetting can be a positive, creative tool as well, helping to draw attention to the centre of the frame.
If you notice dark corners, try zooming in a touch, or set a narrow aperture. Alternatively, Photoshop’s Lens Correction filter (Filter>Distort>LensCorrection) does an excellent job of eliminating (or enhancing) vignetting.
Vignetting can add to the mood of a shot.
You’ll usually see this when you’re shooting architecture from ground level with standard to wide-angle lenses. Tilting the lens has the effect of distorting the scene’s perspective, causing the building’s verticals to converge towards the top of the frame.
Either hire or buy a dedicated tilt-and-shift lens, which can be used to straighten verticals, or apply a perspective tweak with the Photoshop Lens Correction filter.
An extreme example of converging verticals.
4… Barrel distortion
Pictures look like they’ve been wrapped around a barrel, with central areas looking larger than they should be.
Rather than standing close and zooming out to fit everythingn in, step back and zoom in. You can also fix subtle distortion using Photoshop Elements’ Correct Camera Distortion filter.
Take a step back and zoom in to reduce the effects of barrel distortion.
5… Chromatic aberration
This is also called ‘colour fringing’, as it produces either red/cyan, blue/yellow or green/magenta fringing around an image’s high-contrast edges – you’ll often notice it when you zoom in on pictures of trees and buildings photographed against white skies. It’s caused by the lens focusing different wavelengths of light at different points.
To reduce chromatic aberration, lens manufacturers typically combine pairs of lens elements with different refractive indexes that work in tandem to cancel out refraction. High-quality (expensive!) lenses often include elements made from specialised hybrid glass to minimise the dispersion of light, such as Nikon ED (Extra-low Dispersion) and Canon UD (Ultra-low Dispersion) glass. The effects of chromatic aberration can also be easily reduced when processing RAW files in the likes of Photoshop CS and Lightroom – we used the Adobe Camera Raw plugin for CS to reduce the fringing in the shot of a palm tree below. The Elements version of ACR isn’t as advanced, yet – you can try a manual approach, by selecting the fringing and reducing the saturation of the area using Hue/Saturation dialog to remove the specific colour.
Before: viewed at 100%. the effects of chromatic aberration are noticeable on the left of the trunk and frond edges…
After: by using the Lens Corrections tab in Adobe Camera Raw, the effects are reduced.
6… Lens diffraction
If you’re using good technique and your images are still losing important detail, it may be due to lens diffraction. It’s caused by using a very small aperture to gain a greater depth of field, and results in a slight softening of the image.
Pretty simple this – where possible, avoid using your lens’s smallest aperture (such as f/22 or f/29). Many landscape pros set an aperture of f/16 by default for precisely this reason.
Using your lens’s smallest aperture – f/22 in this case – can lead to softer images because of lens diffraction.
on Friday, May 13th, 2011 at 11:35 am under Beginner.
Tags: camera tips, lens, lens problems, lenses, Photoshop