I have an Olympus E-300 camera that I've started playing around with. It has a four-thirds (not micro) mount. On eBay, I found a cheap c-mount lens with adapter. I didn't read closely enough to realize it was c-mount to micro-four-thirds adapter.

Is there an adapter that will let me use this lens? Quick search turned up nothing (though it's hard to separate out the four-thirds from micro-four-thirds stuff, micro seeming to be more popular now).

I'm guessing no. This adapter makes the lens sit pretty darn close to the sensor, which would be impossible with the mirror on my Olympus DSLR. I'd like to be certain though.


2 Answers 2


It appears that the C mount had a flange focal distance of a little over 17mm, while the 4/3s system is a little over 38mm (this is due to the mirror).

It's not actually possible without changing the lens or body construction and can't be done with a simple adapter.

However, m4/3 is a little over 19mm. You may get a black border (due the the circle coverage of the lens) but here are some samples.

Looks like it does a better job than on APS mirrorless body.

  • \$\begingroup\$ Ah, flange focal distance, that's the key thing I was missing. Actually, the table from the wikipedia page is handy, because (at least in theory) any lens with the same, or larger, focal distance can be mounted on the camera (of course ignoring a bunch of other stuff that might make it impossible). \$\endgroup\$ Commented Nov 7, 2012 at 18:58

This would need a work around with use of two adapters, which makes the registration discrepancy even wider. You would need a C mount to T mount adapter and a T mount to 4/3 mount adapter. T mounts are often found in microscopy and astro photography.

You will then only get a C mount macro lens. But the focus plane might end up within the lens itself, making it impractical. It might even end up covering the whole sensor, but out of focus and somewhat out of pocket too.


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