Metering Range

EXPOSURE MEASUREMENT-continued

If the black meter needle fails to leave the " A " or " B " positions during auto (or fails to "match" the green needle in manual), even after all possible lens-aperture/ shutter-speed combinations have been tried, then the available light is too bright or too dim for the meter's range. To correct this situation, several measures may be taken, as follows: Switch to a new film (either higher or lower ASA) that more closely matches the available light; mount a neutral density filter on the lens to de- crease the light reaching the film plane; or use artificial lighting (i.e., an electronic flash unit) to increase subject illumination. Remember, too, that the lens in use can greatly influence suitability for bright or dim shooting. For example, a 50mm f/1.4 lens (with ASA 100 film) couples from EV1 (f/1.4 at 1 second) to EV 18 (f/16 at 1/1000 second) for excellent low-light performance; on the other hand, a 200mm f/4 lens proves more usable at bright-light levels, coupling (with ASA 100 film) to EV20 (f/32 at 1/1000 second). Thus, choose the lens carefully to match the existing lighting conditions.

High-Contrast Lighting Situations

When there are substantial brightness differences be- tween the main subject and the background, unimpor- tant bright spots or dark spots can adversely influence the finder reading, and thus the final exposure. To pre- vent under- or overexposure of the main subject under these shooting conditions, some corrective action must be taken to ensure proper exposure of the main subject. Fortunately, the finder's center-weighted TTL metering action (and the memory lock function in auto) simpli- fy adjustments, making for quicker camera operation and more accurate final results.

To compensate for an excessively bright or dark back- ground, target the main subject in the center of the fo- cusing screen while performing metering; this action en- sures that the main emphasis of the meter reading will be on the chosen subject. Then, after completing aper- ture and shutter speed adjustments (and depressing the memory lock to retain the shutter speed, if set to auto), recompose to the desired picture composition and make the exposure without readjusting the camera controls. For example, when shooting landscapes, it is often ad- visable to aim the camera slightly downward during ex- posure measurement to eliminate the effects of a bright expanse of sky; without such compensation, the land- scape may appear underexposed in the final print. Also, for backlit subjects, it may be necessary to move closer to the subject to ensure a proper reading.