Pentax LX

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The LX camera was Pentax's most advanced manual focus camera, launched in 1980 to celebrate the 60th anniversary of Asahi Optical thus the LX denomination. It was Asahi Pentax attempt at entering the professional segment of the 35mm SLR camera market competing with the Nikon F3 and Canon F-1.
When introduced in 1980 it had many unique features and groundbreaking technologies, die cast aluminum-alloy body, Titanium electro-mechanical shutter (horizontal travel), total body sealing, and the Integrated Direct Metering (IDM). all wrapped in a relatively small package. The LX was a modular system, at only 565g, which included a whole system comprised from the start a series of accessories such as 8 interchangeable viewfinders, 12 viewfinder screens, 2 motor drive, 2 data back, wired or wireless remote control, dedicated flashes in addition to the vast range of SMC lenses. It is protected against water and dust. This is probably one of the finest mechanical 35mm cameras ever produced, and very comfortable and easy to handle. The LX remained in production until 1997.
The LX had a hybrid electromechanical shutter; with mechanical speeds between 1/2000s and 1/75s(X) and electronic from 1/60s to 4s plus B. Those were selectable form the speed dial, depending on the lens attached the Automatic mode provided wither Aperture priority (K and M lenses) or full automatic mode (A lenses in Auto mode).

The IDM exposure system was a full aperture, center-weighted, through-the-lens light metering for both automatic and manual modes. The Integrated Direct Metering (IDM) system measures light at the film plane via Silicon Photo Diode (SPD). Pentax's IDM system was at the time considered the most accurate light metering system, the Pentax IDM system measures incoming light at the moment of exposure–after mirror flips up. This makes it unnecessary to add a special circuit to store exposure data. IDM circuitry is thus simpler and more reliable than conventional TTL systems. All IDM metering circuitry, including the metering cell, is located inside the body, not in the pentaprism, so that finder changes do not affect the performance of the metering system. In TTL open-aperture metering, an SPD cell measures light transmitted through the quick-return half-mirror and reflecting off the metering mirror. The IDM system then indicates the photometric measurement in the viewfinder. In the automatic exposure mode the IDM system is switched on at the moment the front shutter curtain starts moving. As the shutter curtain moves, the IDM system makes an integral calculation of incoming light and controls movement of the rear shutter curtain for correct exposure. For automatic exposure in the TTL Auto Flash mode, the IDM system measures only light reflecting off the film plane since the flash goes off after the shutter is fully open. The rear shutter curtain closes after the IDM system determines that enough light has reached the film and terminates the flash.

This system was also the best for long exposures, covering the range from -6.5 EV (125 sec at f1.2) to EV 20 (1/2000 sec at f22) at ISO 100 in automatic mode and in manual from EV 1 to EV 19 (at ISO 100 with f/1.4 lens).

Pentax LX Gold - In October 1981 a special limited edition of 300 LX cameras was produced to celebrate the company's achievement of being the first manufacturer to produce 10 million SLR cameras. On this version all the metal parts are gold plated. The leather covering is brown skin and the plastic parts are dark brown. The accompanying SMC Pentax 1:1.2 50mm lens is similarly finished with brown leather covering the focusing ring grip. It came with a brown ever ready case.
Another special edition of the camera was made in the year 2000 Millennium Models (Y2K/2000 Special Edition), again with the 50 mm f/1.2 lens in a special brushed aluminum finish.


  • Film: 35mm, speeds ISO 6 to 3200 (manual selection)
  • Lens mount: Pentax KA bayonet
  • Viewfinders : Interchangeable viewfinders - FA-1 standard
    • Tricolor display for TTL-measured shutter speeds with green LEDs indicating hand-holdable speeds from 1/2000 second to 1/30 second, yellow LEDs as slow speed warning from 1/15 second to 4 second, and red LEDs indicating overexposure or long exposure and "X"-sync flash-ready light with TTL and dedicated flash units; blue flag indicates automatic at "A" and manually selected shutter speeds; aperture visible in standard FA-1, FA-1W, FC-1 and FD-1 finders
  • Metering: TTL center-weighted (60/40), meter on film plane IDM activated by lightly pressing shutter release button, EV -6 - 20 at ISO 100, f 1.4
  • Shutter: Hybrid Electro-mechanical horizontal titanium focal plane shutter, speeds: mechanical 1/2000-1/75 and electronic 1/60-4 sec
  • Exposure modes:
    • A: Automatic P or Aperture priority
    • M: manual by selecting the shutter speed
    • X: flash sync (1/75s)
    • B: Bulb
  • Dimensions: 144.5×90×50mm with standard FA-1 finder
  • Weight: 565g (19.9 oz.) with Standard FA-1 Finder
  • Manual film transport Single stroke 120 degrees or multiple short strokes to cock the shutter. At 25 degrees stand off position.
    • Up to 4fps and automatic rewind with Winder LX and Motor Drive LX
  • Battery: 2x 1.5V alkaline or AgO SR44/LR44, or 1×CR11108


Pentax K mount SLR Cameras
K2 | KX | KM | K1000 | MX | ME | ME Super | ME-F | MV | MV1 | MG | LX | Super-A | Program-A | A3 | P30 | P50