metering, which was promoted with the catch-phrase "concentration on the essentials", sales of the camera were rather poor. In 1976 Rollei unexpectedly withdrew the SL350 (the last 35 mm camera "Made in Germany" until Rollei went bankrupt) from sale in favour of the SL35 M – a camera derived from obsolete technology acquired through Rollei's purchase of Zeiss Ikon. In comparison to the elegant design of the SL35, the SL35 M was clumsy and unreliable. Next, Rollei went on to develop the SL35 ME, its first SLR with aperture priority metering – some four years after the Japanese. Low-cost mass production in Singapore allowed Rollei to offer the SL35 ME at a very attractive price. In spite of this, sales were well below expectations. Rollei's research and development department continued to follow the basic philosophy it had established for its medium format cameras: adding more electronics. In 1978, Rollei introduced a new, electronically controlled camera, the SL35 E. However, it lacked the reliability that was now expected of consumer products. One weak point, for example, was the mirror mechanism. After Canon introduced the AE-1 (the first 35 mm SLR to include a micro-processor), and Minolta introduced the XD-7 (the first SLR to feature multiple automatic exposure modes – shutter priority and aperture priority), camera buyers lost interest in Rollei and its products; on the other hand, very few noticed the flaws either. As a result, Rollei was relegated to the fringe, its sales lagging well behind Minolta, Pentax, Canon, Nikon and Contax-Yashica. In the mid-1970s, third-party lenses increased in popularity. This trend made it difficult for Rollei to maintain its declining market share because third-party lens makers were reluctant to produce Rollei-compatible lenses; low sales of Rollei cameras made it uneconomic for them to do so. As a result, Rollei's customer base, which formerly consisted of enthusiastic amateurs, was now dominated by casual photographers. Although they generally preferred German-made products, they were much less inclined to buy expensive camera accessories. Nevertheless, Rollei sold 333,000 units of the SL35 and 120,000 units of its successor, the SL35 E, including sales of virtually identical models from Voigtländer. Rollei 35RF The Rollei 35RF was a compact camera with a fixed f/2.8, 38 mm lens. Despite the similarity in names, this camera should not be confused with its modern (2002) namesake, the Rollei 35 RF – a rangefinder camera with a Leica M bayonet