Pentax 35mm SLR Cameras (1964 to 1976)
Asahi Pentax Spotmatics were a family of 35mm single-lens reflex (SLR) cameras manufactured by the Asahi Optical Co. Ltd., between 1964 and 1976.
The 1964 Spotmatic (SP) was one of the first SLRs to offer a through the lens (TTL) exposure metering system. The pre-production camera was originally designed to employ spot metering, but Asahi decided against this. The light measuring system was altered to average metering at the last minute, and Pentax didn't have time to change the name.
Pentax were not the first company to offer TTL metering. Topcon got to market first with a very different system operating at full aperture (something it took Pentax almost ten years to develop), but the Spotmatic sold well, to the point that no other model from any other brand even came close to rivalling its success. The Spotmatic even became the workhorse of many professionals of the period.
The first Spotmatic was entirely mechanical apart from the light meter, which was powered by a 1.35-volt mercury cell. The cameras were focused with the lens at maximum aperture, then a lever depressed to stop-down the aperture and switch on the metering, which employed a match-needle system, visible in the camera's viewfinder. It had a shutter speed range from 1/1000th to 1 second, plus Bulb. The body took lenses with a 42mm Praktica screw thread, and had a removable accessory shoe for flash attachment with FP and X sync terminals on the front of the camera body.
Production of the original Spotmatic was discontinued in 1973.
In 1968 Pentax introduced the SL, which was identical to the Spotmatic, except that it did not have the built-in light meter. Ironically, a clip-on light meter was available for this camera.
In 1971 another budget model, the SP500, was produced. This resembled the Spotmatic but had a top shutter speed of 1/500th and no self-timer. Production ceased in 1974
The Spotmatic II (SPII) updated the original SP, with improvements to the metering system and film transport. It also got a hot shoe for flash.
The third 1971 offering from Pentax was the ES, which improved on the Electro Spotmatic (sold only in Japan). This camera featured open, aperture metering with automatically selected shutter speeds from 1-1/1000th, indicated by a viewfinder pointer (aperture priority exposure). The camera could be set manually, without the benefit of metering, and shutter speeds were limited to 1/60 - 1/1000th seconds.
In 1973 another lower budget SP1000 was added to the range. This was the same as the SP500, but had a top shutter speed of 1/1000th.
Additionally, the Spotmatic F (SPF) joined the line-up. The meter was circuit redesigned, and is constantly active, only switching-off when the light is at EV2 or less. Most importantly, this camera had the capability of metering without stopping-down the lens down.
Finally the ES was upgraded as the ES II, a with a self-timer, shutter release lock, interior viewfinder blinds, and an innovative step-less shutter, offering speeds from 8 seconds to 1/1000th in auto mode. The power supply was changed to modern 1.5v alkaline or silver oxide cells.
Production of the SP1000, SP II, SP F and ES II ceased in 1976.
In 1975 Pentax followed its rivals' leads, and introduced its own lens mount, the K bayonet, plus three new camera bodies: the KM, KX and K2. Some of the functional elements of the K series cameras were quite differently arranged, and it looked like Pentax was exploring new design options.
The KM was almost identical in features and operation to the Spotmatic F.
The KX featured a better TTL light meter using SPD (silicon photodiodes), with aperture and shutter speed information visible in the viewfinder, plus a mirror lock-up mechanism.
The K2 was the flagship model, and incorporated aperture-priority auto-exposure with a manually selectable range of shutter speeds from 8s to 1/1000th.
In 1976 the K1000 was added to the series. It was essential a KM stripped of its self-timer and depth of field preview. This model enjoyed unrivalled popularity as a student camera, and continued to be produced until 1997, eventually selling over three million units.
The other three K series cameras endured for a very short time, because later in 1976, Pentax abandoned the Spotmatic body shape, and introduced a band new, smaller camera series; the M.
My account ends here. It was the end of an era. Mechanical cameras were about to become dinosaurs: it was the dawn of electronic micro-motors, and microprocessors.
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