I am using a MFT camera and have a lens coming in soon. I have a PK -> MFT adapter. The lens is supposed to be Aperture-automatic, SMC Pentax-A 35-105mm F3.5. Now, will it work with the adapter? I don't need any auto aperture, and there seems to be a switch on the ring where you can adjust the aperture via the ring, when switched.
I use PK mount lenses on my Lumix G1 with a PK to M4/3 adapter. As the previous responder has said, usage is restricted to Av aperture priority or M Manual modes. But that is fine the lenses work well like this and mirrorless cameras have certain advantages over using legacy lenses on dslr's not least the "focus assist" modes to help with focus ie magnification and or focus peaking. The only lenses which are problematic are those designed FOR dslr without an aperture ring. On these you can't change the aperture. All the old designed for slr pentax lenses have an aperture ring so the f-stop can be set manually. The lens mentioned is PKA mount but the "A" setting on the aperture ring is irrelevant for usage on mirrorless.
Generally speaking, it will work, for varying definitions of "works". There won't be any autofocus, and you'll have to set the aperture using the lens ring, so you'll probably be stuck in either aperture-priority or full manual shooting modes. And unless the adapter tube is chipped, you probably won't have AF confirmation or the lens EXIF information. But as far as I know, Pentax K lenses can be used just fine as all-manual lenses on adapter tubes for micro four-thirds, and if you're shooting Olympus you should have the added bonus of the in-body stabilization working for you.
The lens will be bigger and heavier than an mft lens, and the 2x crop factor will really work against you if you want to shoot wide, but it should work.