الضبط البؤرى أو ضبط المسافة على العدسة ٢-a .. كتاب التصوير علم وفن

- The rangefinder or reflex camera mirror is not set:

. (a) Pin a page of newspaper to the wall

To test this, do the following:

(b) Mark the center line of the newspaper with a pen.

(c) Attach the camera to a stand and set it at an angle of 45 to the page and to

Exactly one meter from the previously marked line

(d) Adjust the lens. At exactly a meter away

(e) Use the widest aperture lens with the appropriate shutter speed for this aperture

using an exposure meter.

(f) PAGE images by firing the trigger by the avoidance self-timer

shake the camera)

(g) Examine the resulting image

If the marked line is completely sharp, the camera is set. And if the sharpest lines are in front of or behind the specified line, the camera needs to

Set and send it for repair.

Dirty lens or filter: This is a common and easily seen cause. Clean the lens or filter with lens cleaning supplies. Blow the lens first with a blower, then sweep it with a brush, and then polish it with special cleaning paper gently. If it is not cleaned, use one drop of special cleaning fluid and polish the lens with cleaning paper.) Cleaning tools are sold in stores

cameras)

- Shifting the focus of the lens: Some fast lenses change their focus when using the widest pupillary aperture. So use it a hole or two less.
How do you create clarity and sharpness in depth? (Depth of field) We can set the focus of the lens on a specific surface level at a certain distance. But most subjects are three-dimensional. In addition to length and width, there is depth. Here we ask, how can a photographer make his image the limits of sharpness from two dimensions to sharpness also in depth? The answer is narrowing of the pupillary aperture, which leads to:

Blunt Lens: Some lenses are blunt like the lenses of most inexpensive cameras. The efficiency of the lens is also reduced when converting lenses or focal length extenders are used. This defect is rare. These days, as the lenses are currently made very accurately, unless they are disassembled and re-installed by a non-expert person.

The narrower the pupillary aperture (the higher the number 2), the greater the depth of the area that appears sharp in the image, which is what we call the depth of field - the narrower the pupillary aperture, the less the amount of light reaching the film. Therefore, we need a slower shutter speed (i.e. a longer exposure period), and therefore we must resort to the law of immortal photography, which is the law of common compromises to obtain the best possible aperture with the best possible shutter speed within the limits of the available amount of light. 1 -

And we have two directions: (to know that narrowing the pupillary opening increases the sharpness in depth in an extension from the level on which the distance was set) (the first direction: in the direction of the lens and the second direction: in the opposite direction of the lens. It is noted that the increase in sharpness towards the camera is half the increase in the reverse side for the lens

Therefore, the rule is: to obtain the maximum depth of field with the least narrowing of the aperture, the focus of the lens must be set at a distance that is
Then - the depth of the subject to be photographed + + the closest part of the subject:

Example: If we photograph a room and the closest distance we want to make it sharp is two meters, for example, and the farthest distance is five meters, then we have to set the lens at a distance of three meters (2 meters the closest part of the subject + + the depth of the subject = 1 meter, then we search for the appropriate lens aperture from the depth of field calculator on The lens varies according to the focal length of the lens. This is done by observing which lens aperture is in front of the numbers 2 and 5 meters (the closest and the farthest distance), then we adjust the lens aperture to this number, which is the pupil F11.
There is only one, and there is another optical method if your camera is of the type reflex lens and has a button to close the pupil. You can gradually close the pupil until you see all the part you want to photograph sharp in front of you. Adjust the camera to this hole.