Canon's pellicle-mirror EOS — the EOS RT, fixed mirror, fast release, EF autofocus, 1989.
The Canon EOS RT, introduced in 1989, was a specialised EOS body based on the EOS 630 but fitted with a fixed pellicle mirror, echoing the earlier Pellix concept. It used the EF autofocus mount and was aimed at photographers needing minimal shutter lag and blackout-free viewing, such as sports and scientific users.
As a 35mm SLR the EOS RT used the Canon EF autofocus bayonet and an electronically controlled focal-plane shutter with a top speed of 1/4000. Its fixed semi-transparent pellicle mirror gave a very short release time-lag and no viewfinder blackout during exposure. It offered through-the-lens metering, autofocus and a full set of program, priority and manual exposure modes. Being fully electronic, it required a battery to autofocus, meter, advance and fire.
The EOS RT suits users who need the fastest possible shutter response and uninterrupted viewing, such as sports, reportage and technical photography. The pellicle mirror trades a little light from the viewfinder and film for these benefits, so a small exposure allowance applies. It is a specialised early autofocus body rather than a general-purpose everyday camera.
When buying, the fixed pellicle mirror is delicate and cannot be cleaned like a conventional mirror, so inspect it carefully for haze or scratches that affect image and finder. The RT is fully electronic and battery-dependent, so confirm power, shutter reliability and the LCD panel. Test autofocus, all modes, foam light seals and film transport. EF lenses continue on Canon EF and mirrorless bodies with adapters.