54–57. Modern Photography, Volume 52, Number 12; December 1988. They were all unsuccessful in establishing a new paradigm and the rectangular body plus pentaprism head layout reemerged universal again in the early 1990s, albeit usually with a large handgrip and rounded contours. 1981 Pentax ME F (Japan): first built-in autofocus 35 mm SLR. Had passive contrast detection AF system."Modern Tests: Pentax ME-F: 35mm Auto-Focus SLR," pp. 110–117. Modern Photography, Volume 46, Number 5; May 1982"Modern's Inside Your Camera Series #33: Pentax ME-F," pp. 72–73, 110–111, 116, 120, 130, 136, 142, 148, 150–151, 162. Modern Photography, Volume 47, Number 3; March 1983. Autofocused poorly and was not commercially successful."Modern Tests: Pentax SF1: The AF SLR That Does More With K-Mount Lenses," pp. 62–69, 80. Modern Photography, Volume 51, Number 10; October 1987. Schneider, "The Top 20 Cameras of All-Time," July 2008, p. 148 Also had Pentax K–F mount, a unique bayonet lens mount with five electric contact pins to pass focus control information between the ME F and its unique autofocusing SMC Pentax AF 35mm-70mm f/2.8 Zoom Lens."Modern Photography's 46 Top Cameras: Annual Guide '83: Pentax ME F," p. 101 Note that the Ricoh AF Rikenon 50mm f/2 (Japan) lens of 1980 had a self-contained passive electronic rangefinder AF system in a bulky top-mounted box and was the first interchangeable autofocus SLR lens (for any Pentax K mount 35 mm SLR)."Inside Your Camera: Pentax ME-F," p. 110 1981 Sigma 21-35mm f/3.5-4 (Japan): first super-wide angle zoom lens for SLRs. For decades, combining the complexities of rectilinear super-wide angle lenses, retrofocus lenses and zoom lenses seemed impossibly difficult. Sigma did the impossible and reached a 91° maximum field of view for 35 mm SLRs with an all-moving eleven element formula through the maturation of computer-aided design and multicoating. In 2004, the Sigma 12-24mm f/4.5-5.6 EX DG Aspherical HSM (Japan) zoom reached 122°, wider than any SLR prime lens ever made, by taking additional advantage of aspherics and low dispersion glasses. 1982 Ricoh XR-S (Japan): first solar powered SLR. Was a Ricoh XR-7 (Japan) aperture priority AE 35 mm SLR of 1981 modified with two silicon photovoltaic cells in the sides of the pentaprism housing that charged a unique 3 volt 2G13R "5-year" rechargeable silver oxide battery. This battery could be replaced with two regular 1.5 volt S76 (SR44) silver oxide batteries.Jim Bailey, "Phototronics: A solar greenhouse in your SLR? No, but here's