The later Power winder A2 is also compatible, but the Motor Drive MA is not. The AE-1 is a battery-powered (one 4LR44 or 4SR44) microprocessor-controlled manual focus SLR. It supports either manual exposure control or shutter priority auto exposure. The exposure control system consists of a needle pointing along a vertical f-stop scale on the right side of the viewfinder to indicate the readings of the built-in light meter (center-weighted with a silicon photocell). The viewfinder used by the AE-1 is Canon's standard split image rangefinder with microprism collar focusing aids. Design history The AE-1 was the first in what became a complete overhaul of Canon's line of SLRs. The 1970s and 1980s were an era of intense competition between the major Japanese SLR brands: Canon, Nikon, Minolta, Pentax and Olympus. Between 1975 and 1985, there was a dramatic departure from heavy all-metal manual mechanical camera bodies to much more compact bodies with integrated circuit (IC) electronic automation. In addition, due to rapid advances in electronics, the brands leap-frogged each other with successively more automated models. Although Canon had been making quality 35 mm cameras for decades, it had since the late 1950s been overshadowed by rival Nippon Kokagu K. K. and its Nikon cameras. While Canon easily led in the amateur compact fixed-lens market (where Nikon did not compete), Canon SLRs did not have the professional features of the top-end Nikon SLRs. Nikon, with its solid reputation for quality of material and workmanship, held a stranglehold on the prestigious professional SLR market that competitors could not break. The AE-1 was the vanguard of the landmark Canon amateur level A-series SLRs and led Canon's foray into the emerging electronically controlled SLR market. The other members of the A-series were the AT-1 (released 1977), A-1 (1978), AV-1 (1979), AE-1 Program (1981) and AL-1 (1982). They all used the same compact aluminum alloy chassis, but with different feature levels and outer cosmetic plastic top panel. By sharing most major components, including an inexpensive horizontal cloth-curtain shutter, viewfinder information display, and autoflash control, Canon further reduced costs and could undercut the price of the more expensive SLRs then on the market. In keeping with its cost-cutting philosophy, Canon designed the AE-1 to use a significant amount of structural plastic for a lighter and cheaper camera at the expense of being less impact resistant. Canon went to great effort to disguise the use of