MORE ADVANCED GUIDES
Depth of field
Lens aperture controls depth of field
When the lens is accurately focused on a subject, there is a certain depth both in the foreground and the background, which is also considered to be in focus. This area is known as the “depth of field.”
The sharp focus area in the foreground is usually shallower than the sharp focus area in the background.
Depth of field has the following characteristics which should be considered when pictures are composed:
- As the lens aperture decreases, the area of sharp focus increases. As lens aperture increases, the area of sharp focus decreases.
- As the distance from camera to subject is increased, so is the area of sharp focus.
- A telephoto lens has a shallower depth of field than a wideangle lens.
The depth-of-field scale engraved on lens barrel enables you to determine the depth of field in which focus will be acceptably sharp. For example, if you focus on a subject 15 feet away and use an F8 aperture, read the distance opposite the two figures 8. In this case the picture will be sharp from approximately 11 to 23 feet.
Checking the effects of depth of field
MC Rokkor Lenses are designed with a meter coupler which permits them to remain wide open durin.g viewing, focusing, and exposure setting. In order to check your depth of field visually when using these lenses push the diaphragm stop-down button on the camera body after the aperture has been set.
When using other Rokkor Lenses designed for the Minolta SR-1, SR-3 or SR-7, use the preview button on the lens barrel or the, camera’s diaphragm button.
When the diaphragm stop-down button is pushed, after ·you advance the film, the diaphragm closes down to the preset aperture and locks. When the button is pressed again, the diaphragm reopens fully.
Mirror lock-up control
The mirror lock-up control is used in conjunction with the Rokkor 21 mm ultra wideangle lens. When activated, the mirror is locked in an “up” position to prevent it from coming into contact with the rear element of the lens which projects into the interior of the camera.
To operate, turn the mirror lock button downward (clockwise) until it stops. The distance of movement is approximately 135°.
The mirror will return to its usual operation when the lock button is returned to the red mark.
The mirror lock button operates independently of the shutter release and film advance and can, therefore, be activated at any time.
The mirror lock-up system is also helpful for photomicrography, sequence, and close-up photography, as it eliminates the possibility of camera motion caused by the movement of the mirror when the shutter is released.
When the mirror is locked in an “up” position, the exposure meter of the camera cannot operate, and an independent meter must be used.
The self-timer delays shutter release about 10 seconds from the time you press the self-timer release button. This allows time for you to get into the picture.
To operate, advance the film (this will automatically cock the shutter). Next, push the self-timer lever down (about 90°) and then press the self-timer release button. The self timer is now operating, and the shutter will automatically be released after about 10 seconds.
- If the film has not been advanced, the self-timer lever will stop after returning about 45° and the shutter will not be released.
- You can override the self-timer mechanism by pushing the shutter release button either before or after the self-timer has been activated.
When using infrared film it is necessary to make an “infrared focus adjustment.” Atter you have made your normal focusing adjustment, turn the focusing ring to the right to align the distance on the focusing scale with the red “R” mark on the depth-of-field scale. After this adjustment has been made you are ready to shoot.
To determine correct exposure for infrared photography, consult the instruction are enclosed in the film package.
Film plane index
The ø symbol engraved to the left of the film advance lever shows the exact position of the the film in the camera-. It is used to precisely measure the distance from subject to film for close-up photography and photomacrography.