Commercial Photography Technique - Good Lens Technique and Solving Common Problems
1 Stay Sharp
When hand holding, the basic rule is to use a shutter speed of at least 1/focal length.
For example, shoot at 1/60th or faster with a 50mm lens and 1/250th for a 200mm. For image-stabilised
lenses the shutter speed can be approximately two stops lower. When using long lenses or shooting at
shutter speeds slower than 1/60th second, a tripod (or bean bag) is essential. For long exposures of 1/30th
second or slower use a remote release and/or mirror lock-up. Locking the mirror up prior to shutter release
avoids internal camera vibrations.
2 The Right Aperture
The ‘right’ aperture really depends upon the lens you’re using and the effect that you want to create.
Architecture usually requires a small aperture whereas wildlife of sports require a fast shutter speed and
therefore a wide aperture. For some subjects you’ll have to make a compromise. Just enough depth of field to
get the main subject in sharp focus, but not so much that the background becomes distracting. A midway
aperture of around f/8 is often best. It’s also vital that you select an aperture setting that provides sufficient
shutter speed to stop subject movement.
3 Accurate Focusing
The most important aspect of any picture is that the main subject is in sharp focus. If your camera has multiple
focusing points, select just one rather than a cluster, so that you have full control over the point on which the
lens focuses. The central focusing point is the most sensitive (and accurate). Make sure that the focusing
point is directly over the optimum part of the picture. For example, the subject’s eye or the foreground
interest of a landscape. If necessary, use focus lock and then recompose. Alternatively, switch to manual
focusing or ‘LiveView’ for ultimate control.
4 Identify and Fix Common Lens Problems
All lenses suffer from some or many inherent problems, such as flare, vignetting, and barrel distortion. See the
next section for practical ways to overcome them.
5 Make the Most of a Superzoom
There’s always a tendency to zip straight to either end of a superzoom – wide angle and telephoto – as they
provide the most extreme view of a scene. But you should use the full range of the lens. Some points to
remember:
Superzooms are slow – often f/6.3 at the telephoto end. This leads to slow shutter speeds so make sure you
support the lens and camera well, particularly when shooting at the long end.
Be aware of ‘zoom creep’. Pointing the lens directly up or down, you may notice that cheaper lenses zoom
slightly in or out.
Don’t expect miracles, optically, with zooms that take in such a huge range of focal lengths. You’re paying for
convenience in a small package. But they will allow you to react faster to situations that someone carrying two
or three lenses covering the same focal lengths.
6 Keep your lens clean
A clean lens free of dust, smears and moisture will perform to its full potential. See ‘Lens Hygiene’ section.
Common Lens Problems
1 Flare
Lens flare appears as brightly coloured polygons or streaks across the picture and it can also reduce contrast.
This often occurs when the sun is very close to the edge of the frame, such as landscapes and backlit subjects.
Zoom lenses are more susceptible than primes. To limit flare use a prime lens if possible, fit a lens hood and
shield the lens to prevent the sun’s rays from directly striking the front lens element. Flare spots can be
removed in Photoshop using the Cloning Tool and contrast can be restored using Levels and Curves.
2 Vignetting
Vignetting (or light fall off) is the unwanted darkening of the corners of an image caused by less light reaching
the edges than the centre of the frame. This may be due to an physical obstruction, such as an added filter or
the result of light hitting the aperture at an acute angle. Wide-angle lenses are particularly prone to this
problem, especially when used at wide apertures and it’s most noticeable with a plain background, such as the
sky. To avoid physical vignetting shoot without filters, zoom in a little and attach the lens hood properly.
Overcome optical vignetting by shooting at a smaller aperture. Many RAW converter packages have vignetting
reduction tools for use in commercial photography.
3 Barrel distortion
Barrel distortion is a lens effect that causes straight lines to be bent aqway from the centre of the image
producing a barrel shaped appearance. It’s a common problem of wide-angle lenses (particularly cheaper
models) and is most obvious on images of architecture. It’s impossible to avoid this aberration in the field, but
Photoshop offers a dedicated solution. Choose Filter>Distort>Lens Correction.
4 Colour Fringing
Colour fringing is caused when a lens is unable to bring all colouirs to the same point of focus. This is seen as a
coloured ‘line’ (usually magenta) around the edges of subjects particularly when backlit. It’s most evident with
long telephoto lenses and very wide angles and digital cameras worsen the effect. Top-end apochromatic
(APO) or ultra low dispersion glass lenses have been corrected to solve this problem but these are expensive.
5 Pincushion Distortion
Pincushion distortion is the opposite of barrel distortion and is a defect that causes straight lines at the edge of
the frame to bend invwards at the centre. It occurs most frequently with telephoto lenses ( especially at the
tele end of a zoom) and is quite common with compact cameras. To reduce this problem in the field, shoot
with a shorter focal length lens or compose the main subject in the centre of the frame and crop it later.
How to look after lenses
A lens that’s covered in smudges or dirt will reduce image quality, so it’s important to clean them regularly. First, use a brush to remove dirt that might scratch the lens. Then add a few drops of optical cleaning fluid onto a lens cleaning cloth or microfiber towel. Gently rub the lens from the centre outwards to remove smudges. Once dry, breathe on the lens and use a dry lens cloth to remove any residual cleaning fluid.
This article shows the quality and variety of techniques that customers benefit from as part of our commercial photography and architectural photography service. Call now to discuss your requirements and timescales on 079101 68536.
Copyright - Adam Coupe Commercial Photography 2008
