I have few questions. I'm using a four-thirds system (an Olympus E-410)

If I use a Minolta MC Rokkor-PF 55mm f/1.7 prime lens:

  1. Can I use this lens with a Minolta MD/MC adapter?

  2. Will I lose auto focus? Can I set the aperture with the camera controls?

  3. Do I always need to use the camera's "M" mode with manual auto focus?

  4. What would be the equivalent focal length on four-thirds for the Minolta 55mm?


1 Answer 1

  1. Yes, you can use that lens on an MD/MC adapter for four-thirds--any manual focus SLR lens that has an aperture ring can be used with the appropriate adapter ring.

  2. Because the lens doesn't do any electronic communication (and if it did, the adapters wouldn't translate it) any function that involves the camera "talking to" the lens doesn't happen. You must manually focus and set the aperture with the rings on the camera. You must shoot in either M or A mode because the camera cannot control the lens's aperture, and you must perform "stop-down" metering (i.e., metering must be done with the iris of the lens actually closed down to be accurate). The aperture setting will not appear in the viewfinder/LCD. You will also, unless you use a chipped adapter, be missing the lens EXIF information (i.e., lens name, focal length, aperture setting used, etc.)

  3. No, you don't have to be in M mode, you can use the camera in A mode, but you will have to manually focus. You can use A mode because the camera can still adjust the shutter speed, as that's a camera body function, not a lens function.

  4. As always, the crop factor on a four-thirds sensor is 2x, so the 135-format (35mm film) equivalency field of view for a 55/1.7 would be 110mm, so it will frame like a short telephoto would on a full frame sensor or 35mm film. However. The lens still remains a 55mm lens. The focal length of a lens doesn't change just because you put a smaller sensor behind it.

Also be aware that the distance scale and the DoF scale will not be accurate for four-thirds format.

  • \$\begingroup\$ I have no clue, but it's what the Olympus FAQ on using OM lenses on the E-410 says. :) \$\endgroup\$
    – inkista
    Commented Dec 17, 2014 at 0:45
  • \$\begingroup\$ @HenkHolterman thanks for the detailed reply. I'm wondering about the point 2. Without knowing the aperture value from the lens how my camera meters the correct exposer? If I forget about the camera metering, without having the EV display, How do I set the correct exposure to 0 \$\endgroup\$
    – inckka
    Commented Dec 17, 2014 at 1:46
  • \$\begingroup\$ @inckka Your camera's metering should work with accurate EV display--that is, it can perform stop-down metering. It should automatically switch to doing this when it can't sense a four-thirds lens (i.e., there's no communication). What you won't see is the f-number of the aperture used. The EV will be fine as long as the lens is actually stopped down (i.e., setting the aperture changes the iris opening to what you want). \$\endgroup\$
    – inkista
    Commented Dec 17, 2014 at 2:27
  • \$\begingroup\$ Do all MFT cameras support A mode with a passively adapted lens? Not all mirrorless cameras do! \$\endgroup\$ Commented Jun 7, 2019 at 18:23

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