There are eight common faults camera lenses may have that are described in this article. A lens may noticeably suffer from all of them or maybe just one of them. The degree to which the problems occur will also vary from lens to lens.
With most of these problems there is very little you can do. If your lens has one or more of these problems you are stuck with it. The only solution is to trade your lens in for a better quality, more expensive option.
Not surprisingly paying more for a lens either reduces the severity of the problems or makes them go away altogether. A lot of the issues described here only become serious issues if you plan to make large prints of your photos or if you view them at full resolution on a computer screen.
How much these issues bother you will depend on how much you treasure ultimate quality. If you are looking to sell any of your photographs the faults listed here can seriously decrease your chances of making a sale.
Chromatic aberration adds a colour to the edges of an object. Purple is the colour that occurs most often. This is why chromatic aberration you may see it referred to as purple fringing. I have also seen examples of chromatic aberration in red, blue and green.
The fringing usually appears around the edges of light objects, especially white ones. Another place where is can be seen is at the top of trees where they meet the sky. Normally it is at its most prominent where a light object is surrounded by a much darker colour. It can also occur where a reflective object is caught by a light source such as the sun.
This is quite a common fault in compact digital camera with extra long zoom lenses. I have also noticed it in kit lenses that come with entry level Digital SLRs.
Lens flare can easily ruin or detract from a great picture. It occurs when a light source, usually the sun, reflects off elements within the lens. This is more likely to be a problem with cheaper zoom lenses. Prime lenses are least likely to exhibit the problem.
There are a number of ways to reduce the problem. To start with, look out for lenses with anti reflective coatings. The coatings reduce reflection levels and therefore reduce unwanted flare. Next up is a lens hood. These are a great little investment. There are two types of hood you can go for. The first is a round hood. The second is a petal shaped hood. The petal shaped hoods tend to be the best bet when it comes to combating flare. Finally taking care with composition can help to eliminated lens flare.
Barrel Distortion is most noticeable in any photograph where there are straight lines. Therefore the easiest way to test for barrel distortion take a photo of a grid, newspaper or a brick wall. If the centre of the grid appears to bulge out towards you then the lens suffers from barrel distortion. This is similar to a fisheye effect.
It tends to be most noticeable with wide angle lenses or a telephoto lens being used at the wide angle end. If a lens suffers from barrel distortion it is likely to become more noticeable as you move in closer to photograph a subject.
Camera Lens Introduction
Buying Your First Lens
Camera Lens Types
Camera Lens Brands
Buying Second Hand Lenses
Digital SLR Crop Factor
Caring For Your Camera Lens
Common Lens Faults
Camera Lens FAQs
Pincushion distortion is the opposite to Barrel Distortion with the centre of the image appearing to become more distant. It tends to crop up more with telephoto zoom lenses.
Vignetting is where the corners of a photo are darker. On occasion vignetting is used by the photographer to draw attention to the centre of the photograph. Normally it is unwanted.
Lenses are more prone to vignetting when the aperture is wide open. Therefore decreasing the aperture may help to resolve this problem.
In general the quality of the lens you use will have little impact on the vividness of the colours produced by your Digital SLR. On the whole the colours produced are down to the technology built into the camera body. One area where the lens can have an impact though is the level of contrast showing in the photograph.
Maximum contrast is usually achieved with mid range aperture sizes. So if you are not content with the contrast levels in your photos try changing the aperture size to see if this improves the overall look of your photos.
If you make larger prints of your images you may see a clear difference in the sharpness of your prints when comparing photos taken with cheap and expensive lenses. This is especially true when pushing the lens to its limits with the aperture either wide open or narrowed down as much as possible.
The biggest difference is often as you move away from the centre of the photograph and out towards the edges of the shot.
Bokeh occurs in areas of photographs that have been thrown out of focus. Bokeh appears as jagged looking circles. While all lenses produce Bokeh a good quality lens will produce it with a much softer look. This helps to make it blend into the background or even give it its own stylish look as part of a photograph. As a rough rule of thumb the more you pay for a lens the better your Bokeh is likely to look. Cheap lenses, including those that are sold as part of a Digital SLR kit can suffer a lot from bad Bokeh.