35 mm SLR Cameras

The Camera

         This camera is one of the most highly developed of all cameras; the digital SLR is based on the camera.   The basic idea is using a hinged mirror to reflect the image formed by the camera lens onto a viewing screen, until just before the moment of exposure.  In a digital SLR the sensor displays the image on a screen until just before the data is saved to the memory.

         The SLR viewfinder system uses a mirror to turn the image the right way up and a pentaprism (basically a 5 sided block of glass, silvered on 3 faces) to correct the left to right reversal.   The pentaprism also offers a compact, but comfortable long optical path between the screen and the eyepiece, which are really only an inch or so apart.   This reduces eyestrain and the need for complicated wide-angled eyepiece optics.   With the SLR there is a wide selection of interchangeable lens, focusing screens and viewfinders.

 

         The greatest single advantage of the SLR camera is total absence of parallax error.   You can see exactly what the lens will place on the film, the precise distance focused and by stopping down the lens, the limits of depth of field and as lens are interchanged the new field of view is automatically visible on the screen.   The camera can be attached to a telescope or microscope or be fitted with diffusers and masks over the lenses and you are still able to see the precise image the lens will produce.   The SLR camera also has solid state through the lens metering, zoom lens and motor drives.   There is an ever-widening equipment system built around the SLR camera.

         A basic SLR camera consists of a lens and a body, which incorporates a viewfinder, film speed dial, shutter release, film advance lever, exposure counter, rewind knob, rewind release button, mirror, focusing screen, pentaprism, and built in through the lens metering system.

 

 

Operation of the 35 mm SLR CAMERA

  

1.    Set the ISO number on the Film speed dial usually on the shutter speed mounting.

2.    Look through the viewfinder, turn focusing ring on lens barrel until important subject material in view  appears sharp.

3.    Select appropriate shutter sped or aperture according to visual requirements, i.e. to stop or accentuate movement, or to increase or decrease depth of field.

4.    Select mid tone grey of subject avoiding incorrect readings caused by very dark or very light areas.

5.    Adjust either shutter speed or aperture until 'floating' indicator needle in viewfinder is centered between the plus and minus indicators. (Some cameras will have lights rather than a needle – green light is correct).   The camera is now set to correct exposure.

6.    The picture area covered corresponds to the edge of the viewfinder frame.

7.     

Check focus, compose image and gently release the shutter, then wind lever through to next frame.