Traduction de Luc Moreau

In 1980, Pentax introduced the LX, which aimed to compete directly with the Nikon F3 on the niche of professional SLRs.  For the record, that year marked the sixtieth anniversary of the company, hence the name LX, i.e. 60 in Roman numerals. With this camera, Pentax seeks to (re-) conquer the professional side of the 24x36 market, which they had gradually neglected since the late '60s, when they confirmed their position in the niche of medium format cameras.
The main features of the LX are:

• K bayonet lens mount,
• Aperture priority automatic or coupled semi-automatic metering
• TTL flash
• Real-time measurement on the film plane during exposure
• Viewfinder with interchangeable focusing screens
• Timer, depth of field test and manual mirror lock-up (controlled by a single lever and push button)
• Wide range of accessories and options.

The electromechanical shutter, focal-plane with horizontal travel, had titanium curtains. Mechanically controlled speeds in the range from 1/2000 sec to 1/75 of a second (which is also the X flash sync) and electronically controlled in the range between 1/60 sec to 4 sec. The bulb, and manual speeds can operate without a battery. The auto exposure is electronically controlled continuously between 1/2000s to 125 seconds. Cocking lever, shutter release lock. Speed adjustment by knurled knob on the top, next to the release button, and featuring an "A" position (for the automatic exposure with aperture priority). Setting the film speed and exposure compensation was done using the dial under the rewind crank.
Metering: The weighted integral measurement is done at full aperture, through the lens (TTL), in automatic and semi-automatic modes. A silicon cell is positioned on the "floor" of the chamber and oriented to measure the light reflected by the shutter curtain thanks to a grid printed on the first curtain (18% gray) or in real time on the curtain and the film plane for the slower speeds. The range of sensitivity was from ISO 6 through ISO 3200.
Information in the viewfinder is displayed by line of  LEDs moving next to the speed scale (green LED = correct exposure, orange = slow speed, risk of camera shake, red = over-or under-exposure). A colour flag indicates the automatic or manual modes. A small window near the bottom of the prism viewfinders allows for reading the aperture selected on the lens.
Lenses: The Pentax LX accepts all bayonet lenses in K mount (standard introduced by Pentax with the K1000).  The standard lens is the SMC PENTAX-M 50mm F: 1.7 or better F: 1.4 as pictured here (the lenses of the SMC series had introduced multi-layered coatings). An adapter ring allows the use of M42 screw mount lenses, like the Super Takumars (subject to stopped-down metering though).
Accessories: a wide range of accessories makes the Pentax LX System professionally complete.