DIGITAL CAMERA TESTS
The following are essential calibration tests that can be done either with a compact or SLR digital camera, and will help you to become both more familiar with your particular camera, and be more likely to get the best use from it.
RESULTS
The best way to judge the results of all of these tests is to print them out (photo in ink jet prints) at A4. Failing this, all images should be viewed (with Photoshop, or any picture viewing software) on your computer’s monitor, at a size of 200–300%. Remember that actual screen resolution is 92 dpi.
WHITE BALANCE TEST
In different lighting situations, take pictures using ‘AUTO’ white balance, and also the specific white balance calibrated for that lighting balance. These include (usually shown by symbols on your camera): sunlight; cloud; overcast; tungsten; fluorescent (often more than one of these); flash; and ‘Preset’ or ‘Custom’ white balance. For best results, take pictures using all of these for every shot. You can then get to know when your Auto white balance is good enough, and when you instead need to set the camera for the specific light balance you are in. Compare visual results carefully.
(CUSTOM WHITE BALANCE)
Take a piece of clean A4 white paper, hold it in the same light you are shooting in, and make a test shot of just this (filling the whole frame), following the camera’s instructions under the ‘Custom’ white balance setting. This is the most accurate way to achieve neutral white for the light you’re in.
ISO (ASA) TEST
ISO is the sensitivity of your recording chip, to light. Low ISOs need more exposure (slower shutter speed and / or larger aperture) or light; higher number settings need less. Generally for best enlargement capability, use the lowest ISO you can (see ‘Minimum Shutter Speed Test), since the higher ISO you use, the more ‘noise’ or grain will show in your image resolution (colour/sharpness).
Choose a light situation that will allow you to use all the ISO settings; maybe outside in daytime but not in direct sunshine. Set your exposure mode to ‘Program’, and take pictures using all the ISO settings in turn (the full range is 50, 100, 200, 400, 800, 1600, but your camera may have fewer settings). The exposure will change each time (e.g. going from 50 to 1600 ISO, exposure might be: 1/60s@f4; 1/60s@f5.6; 1/60s@f8; 1/125s@f8; 1/250s@f8; 1/500s@f8).
The best way to determine how high an ISO you can use, with an acceptable level of noise, is to print out all these images at A4. Usually anything higher than 400 ISO is thought to be too grainy for good enlargements.
MINIMUM HAND-HELD SHUTTER SPEED TEST
Similar to the ISO test, you need to find a lighting situation where you can do several exposures of the same thing, at different shutter speeds (a low ISO is best to judge the results. A subject with a lot of fine detail, sharp texture, or straight lines is best. Set your camera on Shutter priority (S, or TV), and do use the following shutter speeds, hand holding the camera (these are fraction, but appear as whole numbers on your display): 250; 200; 160; 125; 100; 80; 60; 50; 40; 30; 25; 20; 15; 10. This means you will have shot from 1/250s to 1/10s in 1/3 stop increments. Look at all of the images at 200-300% on your computer screen, and decide which first shot shows an unacceptable level of camera shake. This is usually below 1/60 or 1/50 second. The image with the slowest shutter speed showing sharp detail with no blur is your minimum shutter speed for hand held shots.
For long focal length lenses (100mm or above, for full frame cameras), you need to assume that the lowest shutter speed for hand held shots is using 1/focal length of the lens: e.g. 1/250s for a 250mm lens, etc. You can also do the same test as above, with long lenses; particularly useful for lenses with an image stabilizing mechanism (which can allow you to get away with much lower shutter speeds than otherwise).
MINIMUM FOCUSSING DISTANCE
This is an easy one. It’s a good idea anyway, if you have one, to set your camera to give you an audible signal (beep) when the lens is focussed on your subject. Also, be aware of the auto focus area in your viewfinder (usually best in the middle).
Simply move yourself closer and closer to a subject to find the minimum distance at which the lens will focus on the subject. You can try this with the whole range of a zoom lens, and also with and without any macro settings (sometimes shown as a flower symbol). Some lenses have a special macro setting at the wide angle to normal end of the lens (especially on some compact camera models), and can focus very close. The actual minimum focus distance may be different at different focal lengths of the same zoom lens (often a longer distance for the telephoto end). With this in mind and also the fact that beyond 50mm (around 35mm on small sensor sized cameras) you need to assume 1/focal length as longest hand held shutter speed, it’ useful to test both the wide angle and the telephoto end of each zoom lens,.
The best results for really close up work (down to a ratio of 1:1 or life size), you have to use a macro lens which is designed for this. Usually these are very sharp lenses, and 60-100mm focal length lenses are good for close up portrait work as well as closer macro shots.
Remember that you need to use a shorter shutter speed for longer lenses (see above); also (very important), that the closer you get to a subject, the less depth of field you will get.
LENS FOCAL LENGTHS
Whether you’re using zoom or fixed focal length lenses on your camera, it’s a good idea to get an accurate sense of the angle of view (this is how wide your lens goes) and field of view (the composition contained within the frame) each lens covers.
You can do this at each end of a zoom lens, either using your hands spread out, fingers touching, or any other visual tool that will help you to know the limits of what you will get from every lens focal length, before you pick up the camera. If you’re using a DSLR and have more than one lens, at least you will come to know which lens to put on to get the shot you want.
Remember: wide-angle lenses have a wider angle of view and distort (expand) perspective and relative distances, while telephoto lenses compress (shorten) both of these, and show a narrower angle of view.
EXPOSURE COMPENSATION
The +/- button on your camera is the most useful editing tool you have. Get used to looking at the first shot you make, on your viewing screen, and then making a decision as to whether you need to adjust the exposure to make it more accurate. You can often use one adjusted exposure for several series if the ambient light remains the same. Get an idea of how much to adjust; one third, two thirds, or a stop or more. Often 2/3 of a stop is a good default. Remember that your camera’s built-in light meter will only read light reflected off all the subjects within your composition, that will always give you an exposure based on an ‘average’ scene (18% grey), whereas many compositions will not be average. For a quick version of this, you can always set your camera to AEB (auto expose bracket), which will give you three shots spread across the exposure range you set it; and if you also use ‘multi’ instead of ‘single shooting, you can then keep your finger on the shutter button and only knock off three frames.
FLASH EXPOSURE COMPENSATION
This feature is either found in your menu or on the fascia of your camera back with this symbol: +/-. It is also good to set this and leave it at a default setting, either -1 or -2 stops, depending on how far away from your foreground subject (usually people) you are. To get more power from a built-in flash on your camera you can always set the compensation into the plus, but you may find that the results are garish and not subtle.
Remember if you’re shooting in low light (say at a restaurant) and want to use the built-in flash to give more light, not to use the Program setting. If you do, the default shutter speed (which you can’t change) is 1/60 of a second, when probably the ambient light isn’t enough for this, and you would need a much slower speed like 1/15 or even 1/8 second. Also if you use the flash on full power it will try to light everything it sees including all distant parts of the composition, which it can’t do – instead making the foreground subjects much too light.
Instead, set the camera to TV or S (shutter priority), find the correct exposure for the ‘ambient’ (existing) light, and test how much to reduce the flash output by trying one shot at -1 and one at -2 stops. Flash will freeze movement, so if you’re careful (on auto white balance) you will get an image that won’t overexpose the foreground with the fill-in flash, and also has a more realistic ambient-light background light balance by using the appropriate slow shutter speed.
© James Bartholomew 2009
Email: james@jamesbartholomew.com
Photography Made Simple 
Leave a Reply