The SLR camera has stood the test of time, moving now into digital media.
The "best" of anything, including cameras, is largely subjective. You might like a single-lens reflex camera that never was very popular just because it "feels" or looks good to you. So "best" in the case of SLR cameras, based on professional and advanced amateur popular use, may not be the best for you. These cameras, however, stood the test of time and use under a variety of circumstances.
Nikon F2
Nikon's successor to its original system camera, the F model, was the F2. It was popular with professional photographers long after it originally was introduced in 1971. Heavy by today's standards, the Nikon F2 featured many wide-angle and telephoto lenses in its system, as well as interchangeable focusing screens, film data backs and viewfinders. It had a top shutter speed of 1/2000th of a second and was an entirely mechanical camera.
Pentax LX
Pentax never really had a 35mm SLR system camera until it introduced the LX in 1980. Still sought after by collectors and professional photographers alike, the LX, like all system cameras, used very wide-angle lenses in a range through normal lenses up to super-telephotos. It also had changeable viewfinders and focusing screens.
Canon AE-1
Canon was around for a long time before it produced the AE-1 in 1976, but this particular camera was a major innovation for the company. It worked well under the hard-knock conditions of the pro as well as for the advanced amateur photographer shooting the Grand Canyon on vacation.
Leica R7
Leica became famous for its superb optics and craftsmanship on its rangefinder camera before entering the SLR market in 1964. The R7 35mm SLR was released in 1992 and was the pinnacle of the original "R" line before the camera was fully redesigned with the R8.
Hasselblad 500C
Hasselblad became the standard high-priced medium-format SLR camera with wedding and portrait photographers largely because of the 500 C camera body. This camera came on the market in 1957. Everything is interchangeable. You can use different film backs for 120 or 220 film. You can use some of the best Carl Zeiss lenses ever made. You can use the traditional waist-level viewfinder or a metered pentaprism. The camera itself is entirely mechanical, meaning it does not need batteries.
Pentax 645
The Pentax 645 SLR uses 120 or 220 film and made advances over the standard medium-format SLR. It has through-the-lens metering built in as well as a power grip for easier maneuvering. It does require batteries to function. It produces 15 or 30 6-by-4.5 centimeter images on 120 or 220 film, respectively.
Mamiya RZ67
Mamiya's RZ76 medium-format SLR featured the full component system of other similar cameras, but added a bellows to focus the lens. You can revolve the the film backs on the Mamiya medium-format cameras, making it easier to take horizontal images with the appropriate film back. It needs a battery to operate.
Bronica ETR-Si
Another medium-format SLR, the Bronica ETR-Si allowed the full use of many viewfinders, lenses and film backs. Like other medium-format SLRs, the Bronica has two shutters, one in the lens and one in the camera body. These function together. The ETR-Si was the last of the ETR line introduced in 1989.
Nikkormat FT
Nikon's first attempt at reaching the consumer SLR market, the Nikkormat FT, was released in 1965. Another all-mechanical camera --- except for the use of the meter --- the Nikkormat FT brought the solid reputation and quality of the Nikon to the consumer.
Pentax K1000
Perhaps the lowliest SLR on the list, the Pentax K1000 was the low-end of the Pentax line when it was introduced in 1976. It still had the bigger size of the previous generation of 35mm SLRs, but it also was rugged. It could use all of the manual focus lenses for the then-new line of Pentax SLRs, but it was cheaper than its siblings. Because you need a battery only for the meter, the camera could be put through a lot of misuse and still work well.
Tags: film backs, advanced amateur, Bronica ETR-Si, camera body, entirely mechanical
