What's the story?
When Sony launched its Alpha 55 DSLR last year, a bit of fuss was made over its clever translucent mirror. Sony forgot to mention, however, that the tech was over 40 years old. Way back in 1965, Canon unveiled the Pellix – an SLR with a fixed, semi-transparent mirror that split the light coming through the lens, sending two thirds to the film and the rest to the viewfinder. The Alpha does similar, but sends that remaining third to an autofocus sensor for quick series photos and autofocussing in video mode.
Why should I want one?
Thanks to their analogue past life, cameras have a real sense of history you just don't get with other gadgets, making it possible to trace their lineage. In this case, while other snappers used through-the-lens exposure metering (Topcon's RE-Super did so in 1963, followed by the Pentax Spotmatic a year later), the Pellix was the first to do it with a two-way pellicle mirror.
What to look for
There are a few common problems you're likely to encounter with a second-hand Pellix. Many have a knackered meter-circuit and the mercury battery it originally used is no longer available. Luckily, a 1.4V Zinc Air hearing aid battery should work just fine. Or you could get a Sony Alpha 55...