The 35mm SLR
The single-lens-reflex camera is the most versatile photographic tool ever made. The first choice of amateur and professional photographers alike, it has been used successfully in all types of photography from landscapes to portraiture to aviation.
What separates the SLR from other cameras is its reflex mirror. The reflex mirror allows the photographer to see "through-the-lens". Click on the thumbnails below to see how the SLR camera works.
The 35mm system
The second reason that the SLR camera is so versatile is that it offers the photographer a vast range of interchangeable lenses and accessories. In seconds the photographer can swap a wide-angle for a super-telephoto and know that the TTL viewfinder will accurately display the resulting image.
35mm or a smaller format?
Today’s SLR cameras are almost universally digital. Digital cameras now offer excellent image quality and are more convenient than shooting film. However, digital-SLRs vary in an important way from their 35mm film-based ancestors.
For decades, the 35mm format has been the dominant format for stills photography. The 36x24mm image size is large enough to produce a high quality image, but is small enough to allow the production of small, lightweight cameras and lenses that make the system versatile enough for all types of photography.
When camera manufacturers began to make digital SLRs in the 1990s, it made sense to base them on successful 35mm designs, especially since a wide selection of lenses was already available.
However, with a few exceptions most digital SLRs do not use 36x24mm image sensors. Most have adopted the much smaller APS sensor. The APS sensor does not offer the same image quality, and only captures the centre part of the image that would be captured by the larger “full frame” sensor. It does however, allow more affordable cameras to be produced - the only 35mm full frame digital SLRs are expensive, professional models. It remains to be seen whether 35mm digital SLRs will become mainstream or whether they will remain a niche product and APS dominate the mass market.
The future of camera design?
The possibilities of digital technology and consumer demands for smaller cameras are pushing manufacturers to rethink the design of the SLR completely. Manufacturers such as Sony, with their successful NEX range of compact-system-cameras, have asked why have a reflex mirror and pentaprism at all? In a digital camera, the image sensor can provide an image preview on an LCD screen. The answer, of course, is that LCD screens and “electronic” viewfinders frequently display a poor quality image and are too slow to use for action photography. Eliminating the reflex mirror also means that the fast phase-detection autofocus systems present in SLR cameras have to be replaced by much slower contrast-based autofocus. This means that at present, the traditional SLR design remains the only camera suitable for aviation photography.