Exposure Compensation

With center-weighted average metering, the camera's meter reads the average brightness of the subjects in a scene, with special emphasis placed on those in the center. Certa~n lighting conditions, however, may necessitate exposure correction. If there is bright light, such as the sun or a window, behind the subject, the meter may be influenced by that light and your subject will be underexposed. On the other hand, if you are shooting an actor on a dimly-lit stage, the meter may be "fooled" and your subject will be overexposed. Thus it is preferable, whenever possible, to meter the part of the scene which requires the most accurate exposure. This is particularly true if the scene has strong contrasts in brightness.

Selective-area metering is less influenced by the surrounding lighting conditions provided the main subject covers most of the 12% metering area. However, if the subject is quite small, some exposure compensation may still be necessary.

Since spot metering allows you to select a small, exact area, it is virtually unaffected provided the subject fills the 3% center spot.

Exposure compensation may also be necessary if you wish to intentionally overexpose or underexpose the shot for creative effect.

You can compensate exposure in any one of the following ways:

1. Manual Exposure

2. Exposure Compensation Dial

3. Adjusting the ISO Setting

 

1. Manual Exposure

After setting the desired shutter speed, turn the aperture ring until the aperture needle aligns with the meter needle. You can now over- or underexpose the subject in one-half f/stop increments simply by turning the aperture ring to a larger or smaller aperture. Note that the diameter of the aperture needle's circle is equivalent to one f/stop. This method of exposure correction is useful, for example, when shooting a subject with strong backlight.



 


2. Exposure Compensation Dial

The exposure compensation dial allows you to make exposure corrections in increments as small as 1/3 f/stop. To ma1te a correction, simply turn the dial, while pressing the lock release button, until the desired correction aligns with the index. The whole numbers are for increasing exposure while the fractions are for reducing exposure. The numbers "2" and ''1/2" are equivalent to one f/stop (or one step of the shutter dial), while "4" and "1/4" are equivalent to two f/stops (or two steps of the shutter dial). The intermediate settings indicate increments of 1/3 f/stop. The table above shows which settings can be used depending on the ISO film speed.

This means of exposure compensation is possible regardless of the exposure mode, and is useful for bracketing. It is particularly advantageous for AE photography since it allows you to adjust the exposure quickly.

IMPORTANT

Once you have made an exposure correction, dc. not forget to reset the dial to ''1." Otherwise, all
following frames will be incorrectly exposed.

3. Adjusting the ISO Rating

You can also correct exposure in manual or AE by changing the film speed setting on the camera.

A film with an ISO rating twice that of another film requires only half the amount of light for correct exposure. Thus if you have an ISO 100 film loaded and you wish to underexpose the subject one f/stop, simply change the ISO setting to ISO 200.

It is possible to over- or underexpose the subject by up to two f/stops using any of these three methods. For compensating more than two f/stops, make the adjustment by changing the ISO rating or by manually setting the aperture and shutter speed.

Note

When it is difficult to determine exactly how much correction to make, bracket the exposure. using any of the three methods.

"Pushing" the ISO Rating

There may be occasions when, due to insufficient lighting, you are forced to use undesirably slow shutter speeds. In this case, you can "push" the ISO setting on the camera to a higher value. Usually this is done by multiplying the normal ISO film speed by a multiple of two, such as two or four. The entire roll of film must be shot at the "pushed" ISO setting; otherwise, exposure will not be correct for all frames. It is also necessary to inform the developing lab of the change in the ISO rating or the film will be incorrectly developed. Hbwever, since not all films can be "pushed" with acceptable results, it is recommended to read the film data sheet or other photographic literature before you try this technique.

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