after the photographer chose a shutter speed to freeze or blur motion. With aperture-priority control, the camera would set the shutter speed after the photographer chose a lens aperture f-stop to control depth of field (focus). Canon – the A-1 Perhaps the most significant milestone of the 1970s era of SLR computerization was the 1978 release of the Canon A-1, the first SLR with a "programmed" autoexposure mode. Although the Minolta XD11 was the first SLR to offer both aperture-priority and shutter-priority modes in 1977, it was not until the next year that the A-1 came out with a microprocessor computer powerful enough to offer both of those modes and add the ability to automatically set both the shutter speed and lens aperture in a compromise exposure from light meter input. Programmed autoexposure, in many variations, became a standard camera feature by the mid-1980s. This is the order of first introduction of 35 mm SLRs, by brand, with a computer programmed autoexposure mode, before the rise of autofocus (see next section): 1978, Canon A-1 (plus AE-1 Program, 1981 and T50, 1983); 1980, Fujica AX-5; 1980, Leica R4; 1981, Mamiya ZE-X; 1982, Konica FP-1; 1982, Minolta X-700; 1982, Nikon FG (plus FA, 1983); 1983, Pentax Super Program (plus Program Plus, 1984 and A3000, 1985); 1983, Chinon CP-5 Twin Program (also first with two program modes); 1984, Ricoh XR-P (tied with Canon T70 as first with three program modes); 1985, Olympus OM-2S Program; 1985, Contax 159MM; 1985, Yashica FX-103. Of the brands active in the mid-1970s, Cosina, Miranda, Petri, Praktica, Rolleiflex, Topcon and Zenit never introduced programmed 35 mm SLRs; usually the inability to make the transition forced the company to quit the 35 mm SLR business altogether. Note that the Asahi Pentax Auto 110, Pentax Auto 110 Super (Pocket Instamatic 110 SLRs from 1978 and 1982) and Pentax 645 (a 645 format SLR from 1985) also had programmed autoexposure. Autofocus revolution Autofocus compact cameras had been introduced in the late 1970s. The SLR market of the time was crowded, and autofocus seemed an excellent option to attract novice photographers. The first autofocus SLR was the 1978 Polaroid SX-70 SONAR OneStep. It used an ultrasonic autofocus system called SONAR. The first 35 mm SLR (the SX-70 was not 35 mm) with autofocus capability was the Pentax ME F of 1981 (using a special autofocus lens with an integral motor). In 1981 Canon