to compete with the Nikon F (see above) with any success. However, Topcons never progressed and Tokyo Kogaku (or Tokyo Optical) quit the consumer camera business circa 1980. 1963 Olympus Pen F (Japan): first single frame (also called half frame) 35 mm SLR.Joe McGloin, "Olympus Pen F Cameras" retrieved 18 May 2007Wade, Collector's Guide. pp. 43–44 Took up to 72 exposures of vertical 18×24 mm frames on 135 film. Had flat-topped non-pentaprism porroprism reflex and optical relay viewfinder,Hansen and Dierdorff, p. 175 and rotary focal-plane shutter.Matanle, pp. 174–175 Well-integrated compact design with excellent interchangeable lenses and large accessory system. The original non-SLR Olympus Pen (Japan) of 1959 helped give 35 mm still cameras that used the standard motion picture frame size of 35 mm film a burst of popularity. It ended by the late 1960s.Jason Schneider, "The Camera Collector: Users of classics unite! You have nothing to lose but convenience!" pp. 60–62. Modern Photography, Volume 50, Number 6; June 1986. Although single frame cameras used standard 135 film, single frame photofinishing was always special-order.Keppler, "SLR: Digital Uproar: Do you feel you're being dragged into digital imaging whether you like it or not? Here's why, and what's coming." pp. 42, 44, 134. Popular Photography, Volume 66 Number 10; October 2002. Kyocera/Yashica unsuccessfully attempted to revive the format as "Double 35" with their Yashica Samurai series (Japan) SLRs in 1988. 1964 Asahi (Honeywell in USA) Pentax Spotmatic (Japan): second SLR with coupled center-the-needle TTL metering (stop-down aperture, full area averaging). Well-integrated, compact and reliable focal-plane shutter, instant return mirror and pentaprism design with excellent non-auto-diaphragm interchangeable lenses.Cecchi, pp. 21–26, 60–66Hansen and Dierdorff, p. 201 Although the Spotmatic's stop-down (manual diaphragm lenses) system was less convenient than the RE Super's open aperture (auto-diaphragm lenses) system, the Spotmatic's two CdS cells on either side of the eyepiece reading off the focusing screen was less expensive and complex than the RE Super's system (see above), and thereby more popular.Lea, p. 24 The Spotmatic's TTL system was (and is) very influential and widely imitated, often with open aperture. It (and rival TTL metering SLRs, including the Canon FT [1966; stop-down aperture, partial area],Shell, pp. 46–48 Minolta SRT101 [1966; open aperture, modified centerweighted]Robert E. Mayer, Minolta Classic Cameras; Maxxum/Dynax 7000, 9000, 7000i, 8000i; SRT series, XD11. First Edition. Magic Lantern Guides. Rochester, NY: Silver Pixel Press, 1995. . pp. 14–26 and Nikkormat FTN [1967; open aperture, centerweighted];Paul