Pentax ME-F

One of the first integrated Auto Focus 35mm SLRs offered – possibly the first. There had been other attempts where the A/F system was fully enclosed within the lens, but in this heavily modified version of the ME-Super, electronics within the camera body used contrast detect sensors to determine correct focus.


Pentax has a pretty long history of innovation and, indeed, of experimenting with camera electronics – as seen in the Spotmatic ES of 1971. The ME-F was a brave experiment, but proved to be ahead of it’s time.

The ME-F on it’s own is merely a development of the ME-Super, it only becomes an auto-focus camera once you pair it with the 35-70 A/F lens – the only one Pentax ever made for the ME-F. The ME-F was never very successful, commercially or practically. The A/F system didn’t work particularly well and the combination was heavy, given the 4 AA batteries required in the lens itself. Traditional PK mount lenses worked fine with the ME-F, as indeed they would continue to do with every Pentax SLR produced since, with the onboard system provided a focus indicator light.

Technical Details

Compared to the ME-Super the differences are as follows:

  • Focus assistance with PK lenses
  • Brighter screen with slightly different finder magnification
  • Used 4 1.5v batteries instead of 2 – presumably needing extra power for the added focus detect circuits and audible feedback
  • Additional controls to the left of the finder associated with the A/F features
  • Electrical contacts in the otherwise standard PK mount

As with the ME-Super the shutter is a mutli-bladed, vertically traveling metal design with speeds from 4s to 1/200th. Exposure is either aperture priority automatic, or fully manual with the push buttons to the right of the viewfinder being used to select shutter speed – just as with the ME Super.

Auto-focus was only possible with the SMC Pentax AF 35-70 f/2.8 lens, which carried 4 AA batteries in an awkward compartment beneath the lens barrel. In use the A/F system was inconvenient, requiring the following steps:

  1. Switch on the A/F on the camera body to either f/2.8 or f/3.5 setting as appropriate
  2. Switch on the A/F at the front of the lens
  3. Press the push-button switch on top or left side of the lens barrel
  4. Hope that focus is achieved
  5. Half press the shutter to lock exposure
  6. take picture

The system may have been inconvenient, but it was also unreliable. As often as not unless the subject and lighting are perfect the lens will simply hunt back and forth trying to lock focus. Slow, awkward and unreliable – little wonder then that the model was short lived and prices were slashed.

All PK lenses will work with the ME-F, with the in body system providing focus confirm if switched on, with two red LED arrows indicating the direction that the lens focus ring must be turned to achieve focus. Of course this only worked on Pentax lenses and those that focused in the same direction as them, many third party lenses did not.

Why it’s special

This was the first auto-focus 35mm SLR, and as such heralded the era of the modern SLR that we know now in the 21st Century. It wasn’t very successful, but is was brave and it was first.

The Museum Sample

The ME-F with winder was purchased in March 2012 on eBay for $59, which included a 50mm f/2 lens and 2x tele-converter. The 35-50 A/F lens was purchased in April 2012 through eBay for $15 – it’s in fairly rough shape with some marking to the lenses and probably does not work, but I wanted it purely for completeness. The A/F confirm works perfectly with the PK lenses in my collection!

Additional Info

  • Manufacturer : Pentax
  • Year Introduced : 1981
  • Year Discontinued : 1984
  • Film format : 35mm
  • Serial Number : 35220003

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