I have a bunch of lovely old full frame K mount lenses (like the 50mm f1.2 and the 135mm f2.5) and the idea of using them in a proper mirrorless body (I have the K-01 and that's a hell of a brick) without the crop and an extra stop of light seems really interesting.

I've seen that there are Mitakon Lens Turbo that adapt Pentax K to Fuji X and Sony E mounts, so using my old lenses at full potential in a NEX 6 or a X-E1 seems like a dream come true, but I am afraid that the extra layer of optics can really degrade the image quality (mostly if it's a cheap made in China glass).

So, does anybody have experiences with focal reducers?

Is it much better the more expensive Metabones Speed Booster (although there are no K-mount versions yet) than the Mitakon Lens Turbo?

Would it be interesting to wait for a µ4:3 adapter (that are said to come out in the second half of 2013) and use my lenses in a GX-1 or an OM-D (the smaller the sensor, the greater f-stop boost, so the ISO noise differences are kind of compensated)?

1 Answer 1


From this PC Mag review, it looks like the center isn't too badly impacted, but the fall off near the edges of the image become pretty severe. I don't have any direct experience, but the general review seemed pretty positive even if there is some barrel distortion.

It seems like unless you need the reduction in the crop factor, you are better off to just use the lens straight up and deal with the fact you get a cropped image.

  • I had already seen that review, but I wanted first hand impressions of people using it on a daily basis xD accepted anyway
    – fortran
    Sep 7, 2013 at 12:24
  • 1
    @fortran - ah yea, you might get a response to something that specific on here, but chances are slim. We don't have the same breadth of users as SO does, so looking for a hands on is probably going to come up blank. Someone might have, but it's not particularly likely to get a timely answer that includes one. (Not to say it couldn't happen, but don't get your hopes up on something fairly off the beaten path like this.)
    – AJ Henderson
    Sep 7, 2013 at 16:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.