قياس التعريض واستعمال المرشحات .. كتاب التصوير علم وفن

Exposure metering and filters:

Do you want to use a special purpose filter in the image? In this case, the candidate factor must be taken into account. This factor is mentioned with each candidate, or you can find it in the table in the Filters chapter in the first chapter

In the case of using a camera that measures exposure through the lens, or there is an exposure meter in it around the lens and the filter covers it when used, the exposure meter usually does the necessary work in most cases, but care must be taken when using a red or gradient filter (see the filters chapter).

In the case of using two filters, the filter factor numbers are multiplied by each other and not added. For example, a filter of modulus 2 and a filter of modulus 4 when used together: the filter factor for both of them is 8, not 6, so it becomes

Exposure metering for close-up macro photography:

If the distance (m) between the subject and the lens is less than about eight times the focal length of the lens (b), then the exposure must be increased in order to avoid a deficiency.
in exposing the film. We know the coefficient of this increase from the following equation:

) the distance between the subject and the lens (2

(The focal length of the lens (2). For example, you want to photograph a flower or an insect using a 35 mm camera with a 50 mm lens and a bellows or extension rings. Then after adjusting the distance. If you see a clear image of the flower on the rough glass. We measure the distance of the flower from the lens, for example, 10 f = cm 100 hmm

... It is necessary to increase the exposure by a factor of 4, or open the pupil by two apertures, increase or decrease the shutter speed by two degrees, so if the exposure is according to the separate exposure scale 1/125 second with a pupillary aperture F A, then the exposure must be made either 1/125 with 4 or 1/ 30 with E or 1/60th with 5.6.

If your camera has a built-in exposure meter that measures the light through the lens, you don't need these calculations. All of this is measured

exposure automatically.

Exposure estimation for some subjects in which it is not appropriate to use the exposure meter:

In some subjects, it is not appropriate to use the exposure meter, either because of the very poor lighting, or because the degrees of lighting are very different within the subject. In this case, the exposure is based on previous experience:

Of course, you can adjust the exposure as you like, as explained above. And you can adjust the exposure to other movie speeds, for example, a 400 ISO movie, reduce the exposure by two degrees, and so on.

It is called modulation that it is correct and it should be noted that this proposed exposure is just a suggestion. Make it a basis for the exposure that you are trying, and to get good results it is preferable to do what was taken (bracketing), which is a picture with the exposure that you think, then take another with an exposure less than one degree or two, and an exposure more than one degree and two degrees, and so on to ensure that you are at least I got a good picture out of the five pictures he took. It is preferable to do this method in all cases in which you fear that you will lose a rare picture by taking an incorrect exposure. Pictures that