[mr.sinha]

Hi,

This may be a strange question, because usually people do it the other way around (i.e. using their Pentax lenses on Micro 4/3 bodies), but how do I mount my Panasonic 20mm f/1.7 lens (from my Pana GF1) on to my Pentax K5?

Anyone tried that yet? Can't seem to find any adapters for 4/3rd lens on Pentax body. Any help/links much appreciated.

Thanks.

[crewl1]

I have absolutely no knowledge of this but would suggest that the reason you see adapters for Pentax on 4/3 and not the other way around is that the registration distance* for a 4/3 lens may be too short, which would require burying the lens in the Pentax body and interfering with the mirror.

*DIstance from rear element to sensor to achieve infinity focus.

[RBellavance]

I have absolutely no knowledge of this but would suggest that the reason you see adapters for Pentax on 4/3 and not the other way around is that the registration distance* for a 4/3 lens may be too short, which would require burying the lens in the Pentax body and interfering with the mirror.

*DIstance from rear element to sensor to achieve infinity focus.

That, and the lens' image circle almost certainly does not cover the sensor of the K-5, which is larger than that of the m4/3 cameras.

[icywindow]

The registration distance for m4/3 is about 19 mm, whereas the registration distance for K-mount lenses is about 45mm - you would need either need a way to mount the lens inside your camera around where your mirror currently is or have optical correction built into the adapter to get the proper registration distance for full range of focus.

EDIT: What they said!

[eddie1960]

I'll Add that if an adapter did exist it would reuire additional optics and therefor degrade the quality ven if the image circle covered the apsc size (which it doesn't)
this of course is the appeal of mft cameras the ability to take almost any lens (also one of the things that makes the GXR M mount module coming out so appealing since almost any lens will be able to mount with an adapter)

[mr.sinha]

Thanks folks. I was hoping I could use this wider angle lens on my K5 instead of buying a new one in that range, but looks like I'll have to abandon that idea for now.

[RBullCZ]

Seems like the easiest way is to get the Panasonic body along with that lens if you really want to use it

[RioRico]

Yes, it can be mounted, either normally or reversed. No, it won't reach infinity focus. You will have Yet Another Closeup Lens (YACL). I have tried this with 20mm and 50mm cine lenses. They're really nice -- if I only want to shoot subjects one inch away.

Register (flange focal distance):

17.526mm -- CCTV/cine
18.0mm ---- Sony NEX
20.0mm ---- m4/3
25.5mm ---- Samsung NX
45.46mm --- Pentax

[mr.sinha]

Seems like the easiest way is to get the Panasonic body along with that lens if you really want to use it

Oh, I have it mounted on a Panasonic GF1 now. Was exploring if I could also mate it with my K5 since the lens is actually a very good one.

[twitch]

There's been a couple of DA21's for sale in the marketplace recently, just sayin'

[johnmflores]

Oh, I have it mounted on a Panasonic GF1 now. Was exploring if I could also mate it with my K5 since the lens is actually a very good one.

Yes, it is a very good lens. Some of it's pixie-dust magic is due to the fact that it's mounted to a Panasonic camera that is aware of its weaknesses and does a little bit of digital trickery to compensate for them. I don't mind at all - I'm most interested in the final image - but even if you could mount it on the K-5 the results may surprise you.

As @Twitch suggests, the Pentax DA21 is a very very good lens as well and the closest focal length equivalent. Slower @ F3.2, but you can crank up the ISO on the K-5 and shoot until the cows come home.