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Are the focus screens interchangeable?

The more complex (and more expensive) cameras designed for specialized use in professional, scientific, or industrial photography often contain interchangeable focus screens (Fig. 18), but this method contributes significantly to the increase in their costs. Ensure a high level of accuracy in placing a fixed screen on a mass-produced object such as a camera and something else to ensure the same or even higher level of accuracy as for a user-replaced screen, often without due care One of the reasons for using interchangeable screens is that Correct focus operation is achieved with lenses of different focal lengths and with different accessories
Figure 18 Interchangeable focus screens
Also, such as telescopes, bellows, or even a microscope: the viewfinder of the segmented image is fast and accurate when using medium focal length lenses (except) it will not be suitable for use at long focal lengths, or at small maximum apertures, since the narrow cone of transmitted light can This can darken one half of the focus assist device, especially when supporting a long lens. On the other hand, the brightness of the extent of the segmented image, nor the fine prismatic regions, will be suitable for long bellows elongation or for microscopy, and it is better to use a simple plain-floor screen.

Do SLR cameras offer different viewfinders?

Most 35mm SLA cameras have a fixed eye-level viewfinder, but larger cameras and some 35mm models have a detachable pentaprism. This can be replaced with a hood and face for direct viewing through the screen (at waist level) or with one of a series Various viewfinders (Fig. 19) TTL metering with automatic exposure control can be added to a number of cameras without metering normally by changing the pentaprism

Why do we need interchangeable shooters in reflex camera?

Although a pentaprism reflex at eye level has advantages over other types of viewfinders, it is not ideal for all types of photography, when diving underwater or descending from the sky for example, the source may be wearing goggles and therefore is unable to bring his eye close enough to the viewfinder's rear aiming to see the entire screen image or to
From above . For accuracy, use a microscope or telescope. An aiming with a greater than normal zoom potential helps to achieve fine focus

Accurate and correct

Most cameras with a fixed viewfinder can be equipped with various other parts to increase their suitability when photographing unusual subjects. Eyepiece magnifiers and right angle correctors can be attached to the rear viewfinder of the camera, making the viewfinder more suitable for some professional applications.