1

I have some Olympus lenses I found at an estate sale, does Pentax make an adaptor to fit these?

3

Pentax doesn't, because Pentax doesn't make any adaptors for other people's lenses. However, assuming this is an old Olympus OM lens, you can get a third-party adaptor — for example, this $40 one from FotodioX.

Note that the flange focal distance of the K mount is 45.46mm, while that of the Olympus OM mount is 46mm. In order for an adapter to be a simple, glassless affair, it would need to be just 0.54mm thick — clearly impossible. So, these adapters are going to need to have glass elements in order to focus to infinity. That means there will be some image quality loss (maybe a lot, from cheap adapters), and inherently, the adapter doesn't provide aperture information to the body, meaning you'll need to use the green button to meter.

An alternative would be to have the lens itself changed. You'll still need to do stop-down metering, but no glass will be involved. If the lenses are really nice (and there were some very nice OM lenses!) this might be worth it.

1

No, Pentax doesn't make adapters for old Olympus OM mount lenses, but Leitax does. The main issue with OM lenses is that the OM mount has a registration distance (the distance the lens is held from the image plane) only 0.54mm deeper than Pentax K's, so a simple ring cannot be used if you want the lens to maintain focus to infinity. Just like using a macro extension tube, if the adapter pushes the lens farther away from the sensor than it was designed to sit, you lose focus capability at the far end of the range. So you either need an adapter with a glass element in it to act like a short teleconverter, or you need a way to reduce the mount distance—like a Leitax lens mount replacement kit.

If, however, the lenses you picked up are digital Olympus Zuiko lenses (four thirds, or micro four-thirds, there is no way to adapt those to Pentax K without losing focus to infinity or severe vignetting (four-thirds has a crop factor of 2x, so the image circle of these lenses isn't large enough to cover an ASP-C 1.5x crop sensor).

See also: Can I use lens brand X on interchangeable lens camera brand Y?

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