The EOS 600 (known for some reason as the 630 in some parts of the world) was not the first EOS camera - that was the 650. It wasn't even the second - the 620 - but in 1989 it was the first with predictive autofocus for continuous shooting, which rather moved the game on for the EOS system. It was an advanced camera in many ways - still only one, non-cross AF sensor, but 5 FPS at a time when that was still rare, interchangeable backs, interchangeable focusing screens, and a rapidly expanding lens range made this a very serious camera. Two buttons on the left of the topplate control input of shooting mode, exposure compensation, and mulitple exposures, along with the main dial behind the shutter release. A large, illuminated LCD gives shooting info. The camera came with a sculpted, interchangeable grip - bizarrely, you needed an accessory one for the remote release socket, despite that grip being standard on the 620. There's a full range of shooting modes - the normal P, Av, Tv and M, plus DEPTH mode, one of Canon's most useful features, and several idiot programmes that I've forgotten how to set - never used them, though. Both my 600s are French - the programme numbers are listed on a little door at the base of the back of the camera, and mine are in French. The door gives access to more buttons, which between them, sometimes in combination, control functions such as AF mode, film speed, self timer, battery check, AEB and custom functions - a first in the EOS range. There's also a mid-roll rewind button. At the back, where the right thumb falls, are the LCD illumination button and the exposure lock button (which used partial metering). On the left, in a similar position, is a mode dial with green triangle (ah, I think that's how you get to the idiot modes...), L for off, A for normal use, and another position to activate the in-focus beep. On the left around the mirror box are the lens release button, DOF preview, and a button marked M to allow control of the aperture in manual mode. The viewfinder shows shutter speed and aperture, and a green focus confirmation light in normal use, a +/- light when exposure compensation is in use, and a flash ready light when used with one of Canon's A-TTL compatible flashguns. A decent range of screens was available, including microprism and split image options. One of the back options was the Technical Back E, one of the most extreme backs ever provided for a 35mm SLR. With a separate keyboard unit, this went way beyond databack functionality into actually programming the thing to follow your will. Incredible accessory, but rather OTT. I do have one, but not the keyboard nor the cable and software to connect to a PC. So what's it like to use? A bit noisy in terms of shutter and wind, and focus, too, when used with lenses of the time with non-USM motors. However, focus is still commendably quick - so long as you have a suitable vertical line for the sensor to lock on to. I find the shape just about perfect for my hands. I used one for quite some years as my second body, and even now one is still dedicated to IR film. At almost the same time, the EOS RT appeared. We've seen these letters elsewhere, albeit with an extra S, and they mean the same thing here - Real Time. The RT is to all intents and purposes a 600 with a fixed pellicle mirror, and has a special Real Time mode (in place of the green triangle) that reduces shutter lag to 0.008 second - it's actually astonishing. Shutter release is very similar to the RTS in this mode. Aside from the mirror and the RT mode, the only real difference is that the camera has extra custom functions. The mirror does mean that less light is transmitted to the film (about 2/3 stop less) and to the viewfinder (1/3 stop) - in most uses, that doesn't seem to matter much in actual use. The mirror has to be kept dust-free, as it's part of the image forming optical system in effect, and will cost a little sharpness anyway. However, the big advantage is continuous viewing, even during exposure - although of course the lens will stop down to working aperture, meaning the viewfinder dims. But it's terrific in use - I particularly like shooting portaits with it. Most of the 600's accessories are compatible, but the Technical Back E is only partially so - can't recall the details, but RT mode has to be disabled for it to work, I think. Having dug this one out again, I want to use it poperly once more - that continuous viewing and real time shooting is compelling. One final note about the shutter (speeded 30s to 1/2000, BTW) - it's one of Canon's shutters that's prone to the oil issue. I've had no problem removing it with a cotton bud and vaguely volatile solvent such as lighter fluid or even isopropyl alcohol, but it's something to look out for.