Meter is also classified by reflected light meter and incident light meter. Incident light meter has the same structure as reflected light meter, but with a plastic cap with 18% transparency. With this cap, the metering is against light, pointing to the camera, at the subject position or simular illumination situation.

Should the reading of meter be adjusted for exposure? We can find a lots of suggestion in books or magazines, which with examples showing these adjustments. For reference, they are fine, but we should not take it as guides, because they are based on specific cases. Even with the same type of topic, it is not possible to have the same equipments, subject and situation.

Memo for metering: 1. Be sure that the battery is sound and healthy, it is always a need to use the best and get them from a famous store. 2. Meter and metering system need warm up, make several test reading, never trust the first reading. With automatic exposure, it is necessary to press the shutter release gently. 3. Use Gray Card for metering, or our palm which needs one stop to be added in general. Be sure the palm is evenly illuminated and parallel to the plane of the expected frame. 4. Be sure that there is no interference from hazy light scattered above or reflection from sand or snow etc. 5. Film must be handled properly, storing with recommended temperature, taking shots before its expiry date and process as soon as possible after.

Metering is the most important technique. In fact, all tone control systems are covering metering, exposure and appropriate film processing.