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  • Writer's pictureMaria Chernetska

What is practical exposure tips?

Point-and-shoot cameras apart, an exposure measuring system (built-in or hand-held) allows you choices and control at three main points: (1) the ISO speed set for the film, (2) the parts of the subject you actually measure, and (3) the alternative ways of dividing exposure between lens and shutter.

If you must get more sensitivity out of the film in dim light, or subject contrast is very flat

and needs a boost, try up-rating (‘pushing’) the film. This means raising the ISO film-speed figure (or using a ‘minus’ setting on the exposure compensation dial on auto-setting cameras). In both cases you then follow this up with extra development. Take care to use a film the makers describe as suitable for up-rating treatment.

Down-rating (‘pulling’) or use of ‘plus’ compensation helps to reduce contrast and grain when followed up by reduced development. This applies principally to monochrome films; it is unwise to down-rate and hold back colour films beyond one stop.

Using the ‘plus’ compensation is also a handy way of compensating for subjects measured by general reading against the light or with large bright backgrounds, which you know will otherwise result in settings which make them underexposed. Or you might use it to allow for a film’s anticipated reciprocity failure when given a long time exposure. Consider the plus or minus settings on the exposure compensation dial as a lighten/darken device for purely creative purposes too, like the controls on many instant-picture cameras.

Always think carefully about what area(s) of the subject you measure. The meter sees the world as an average 18 percent grey (the reflectance of grey card) and as such you, as the photographer, are responsible where you point the camera. Decide the priorities between various tones of your picture. If there is only one really key tone, and the camera does not have spot reading, try to make it fill up the whole frame. With a close-up you can do this by just moving forward (don’t refocus – extra extension may change the reading). If your key subject is inaccessible, take a substitute reading from something convenient that matches it in tone.

The eye is good at judging comparisons. A grey card has already been suggested, but you can read off your hand, lining it up and turning it at angles in the light to match a far subject tone, or find some part of the ground or sky with the right-looking tone. Some cameras have an ‘auto-exposure lock’ (AE-L) button but if yours does not, keeping the shutter button half-pressed will hold this exposure setting when you pull back and recompose the picture, or use manual exposure mode (see above).

Photographing flat objects such as line drawings, photographs, paintings, etc., often brings problems over how best to take a reading. Areas of dark and light are unlikely to be equal. Sometimes you can ‘home in’ on a midtone of sufficient size in a photograph or painting, but the best approach is to read off a grey card (or take an incident-light reading). You can see how important it is when using a built-in metering system, in that it allows you to take a reading and then retain the settings unchanged after reframing the picture, removing the grey card, and so

on. You will have to activate the auto-exposure lock or use manual exposure mode, otherwise the meter goes on taking new measurements.

A more specialist problem concerns exposure reading when using a moving light source to ‘paint with light’ an architectural interior or still life, spreading the light and forming a softer, more even source. Provided the lamp is moved in an arc maintaining the same subject distance throughout the exposure, you can accurately read the light when it is still.

Whatever your technique for measuring the light, deciding the best way to deliver the exposure by means of aperture and shutter controls is always something of a balancing act. Each shot has to be considered on its depth versus movement merits. Occasionally, requirements and conditions work together to give plenty of options, as with a scenic landscape with all its elements static and distant, in strong sunlight.

At other times, they all conspire against you, as in a dimly-lit shot of moving objects at different distances which must all record in detail. In this instance you must think how to improve conditions – perhaps by adding supplementary lighting, altering camera viewpoint to reduce the range of distances, or up-rating or changing to faster film but still keeping within grain and sharpness tolerances.
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