Introduced back in 1976 by Pentax, the MX is a professional, all-manual SLR camera. One of it's most appealing features was the compact body combined with one of the largest and brightest viewfinders of any SLR.
The MX is all manual: it does not feature auto-focus or auto-exposure modes such as aperture-priority, shutter-speed priority, or full program.
Pentax MX's accessories included a film back capable of 250 photographs in one load as well as motorized winder Winder MX (2 frame/s) or a Motor MX (5 frame/s)motor drive and a 2 fps winder, Data backs, Dial Data MX, besides numerous other accessories.
A number of focusing screens were produced
- SC1: ground glass, split image device, microprism ring (standard)
- SA1: ground glass, microprism patch
- SA3: ground glass, microprism patch, for wide aperture lenses
- SB1: ground glass, split image device
- SD1: ground glass, cross collimator
- SD11: aerial image, cross collimator
- SE: ground glass
- SG: ground glass, grid
- SI: ground glass, axis
The current shutter speed and relative aperture are visible in the view finder, the aperture via a window that projects the aperture value from the lens aperture ring into the view finder.
Exposure is set by adjusting shutter speed or aperture until a green LED lights up in the viewfinder. This is an electronic version of the match needle metering of the Pentax Spotmatic and KM series.
The Exposure meter is powered by two 1.5V silver oxide batteries (G13) and is designed to operate as open-aperture, center-weighted Through-The-Lens meter, using GPD cells for fast light response, with tri-colored LED exposure read-out, rapid wind lever and shutter release button acting as meter switch (Pentax MX's weak spots).
- Exposure range: EV1 - 19 (ASA100, f/1.4)
- Film speed range: ASA 25. 1600.
Due to Pentax MX's complete lack of automatic functions, but excellent array of manual controls, the MX is often prefered as a film SLR camera complementary to a classic Rangefinder cameras such as Leica.