Zuiko lens Club

Big Dave · 08-10-2008, 04:47 PM

Hello everyone,
Well I just got around to converting my Zuiko 24mm/2.8 to K-mount. I took a few shots around the house and I am very pleased with it. The 62 degree view has always been my favorite all around focal lenght. It was easy and completely reversable, as long as you use a mount from an extra 50mm for the modifications. I saved the 24mm mount, so I can restore it to stock form, since the 24mm's are worth a few dollars. The appeture lever restraint is needed to keep the lens in manual mode. So lets see just how many OM Zuiko Club members we can find out there.

Dave

*k100d* · 08-10-2008, 06:09 PM

is this lens reputed to be very good?

troyz · 08-10-2008, 06:40 PM

What a fun project!

I'm amazed the conversion works so smoothly -- I'd like to see more disassembly/donor K mount/reassembly photos.

BTW, What focus range do you get with the K mount?

Big Dave · 08-10-2008, 07:15 PM

Troyz,
I will take some pictures when I convert another mount. I stole the converted mount off of my Zuiko 50/1.8 to save time, so I wasn't able to get photos for this thread of the mount conversion. The Zuiko OM lens line has always received good reviews. All of my OM conversions focus over the full range to infinity. I like the compact size on my Pentax.

Dave

Originally Posted by troyz

What a fun project!

I'm amazed the conversion works so smoothly -- I'd like to see more disassembly/donor K mount/reassembly photos.

BTW, What focus range do you get with the K mount?

*k100d* · 08-10-2008, 08:16 PM

now you mention it, that lens is super tiny !

polecat · 08-10-2008, 09:45 PM

Hello all. This is not a Zuiko specific reply but just a little note regarding lens mount conversions. I recently converted a Kalimar 28mm f-2.8 lens (made in Korea) from the supplied Minolta mount to K mount by removing the mount assembly (attached with three screws) and substituting a new mount made from a modified Pentax K T-2 adapter. I discarded the inner ring from the adapter and machined the knurled flange part to the proper thickness to allow infinity focus. I then drilled and counter bored three holes to allow mounting to the lens utilizing the three original screws. The lens is not a very impressive performer but it was free and a fun project. The T adapter seems like a useful starting point for this kind of thing because the thickness of the knurled part allows for a lot of customization with a little lathe work.

Big Dave · 08-10-2008, 11:47 PM

Here is a link to the Olympus history and Zuiko lenses.

Olympus Resources for Zuiko Lenses

Dave

Big Dave · 08-13-2008, 03:30 PM

Hello,
I just finished making a rear light baffle for my OM 24/2.8. I used a M42 screw mount body cap. This screws into the M42 adapter that I used for the conversion and protects the rear element. The plastic chips easily as you can see. See stock cap on the right.

Dave

*pingflood* · 08-13-2008, 06:33 PM

This is interesting.... I have an OM2 that I rarely use, but always loved the Zuiko glass. The lowly 50/1.8 is one of my all time favorite lenses, and I would love to get it working on my K20D. I DO have a sacrificial K-mount clunker or two sitting around too...

If you just redrill and swap the mount from say a 50/2 Pentax how far off proper infinity focusing will you end up?

Big Dave · 08-13-2008, 08:31 PM

pingflood,
It is really a quite simple conversion. The Olympus is 1/2mm further from the sensor then Pentax. The flange on a typical flange style m42 adapter is 1/2mm thick. You remove the OM mount and remove the internal parts. Then carefully trim away the bayonet from the mount. This can be done with a Dremal tool or hacksaw. I dress the mount surface down with sandpaper on a peice of plate glass. I use the self adheive sanding disk used on disk sanders. When removal is done, I use Gorilla glue to glue the M42 mount to the OM mount. Apply a very thin layer and align the mount so the red index marks are close on both mounts. Be careful to position the lens latch slot on the M42 mount, so that it doesn't fall close to the screw hole adjasent to it. Align all of this up dry and mark the two halves with sharpie pen, so you won't have issues when gluing. I clamp the assembly in a vise for a couple hours. Follow the instructions on the glue container. When dry, drill three holes from the inside of the mount, using the existing holes for alignment. A drill press is recomended. Now drill the holes through the M42 mount side for the screw heads, using the three holes in the flange as centers. Clean and debure the assembly thoughly. I tape the holes left by the mount buttons from the outside. I then apply a little JB Weld epoxy to the inside of the mount, to seal the holes. You may have to trim away some of the JB later to allow the mount to seat on the rear of the lens barrel. The next issue is to force the diaphram to manual mode. I used a peice of copper wire to restrain the appetture lever, as seen in my first post of the thread. Install the mount. You can make a nice light baffle from a M42 body cap as seen in my last post. This my also protect the rear element. The lens will focus perfectly from infinity to its closest setting. So far I have converted three a 50mm,24mm and my Cosina 28-7/2.8 zoom. The all work great and cost very little.

Dave

Originally Posted by pingflood

This is interesting.... I have an OM2 that I rarely use, but always loved the Zuiko glass. The lowly 50/1.8 is one of my all time favorite lenses, and I would love to get it working on my K20D. I DO have a sacrificial K-mount clunker or two sitting around too...

If you just redrill and swap the mount from say a 50/2 Pentax how far off proper infinity focusing will you end up?

*pingflood* · 08-14-2008, 08:57 AM

Originally Posted by Big Dave

pingflood,
It is really a quite simple conversion. The Olympus is 1/2mm further from the sensor then Pentax. The flange on a typical flange style m42 adapter is 1/2mm thick.

NOW it dawned on me!

I was looking at my M42 adapter and couldn't figure out how it would work, but mine's a Pentax one with no flange.

Thanks for all your info. So an M42 adapter would be better/easier than trying to put a mount from a Pentax K-mount lens on it? (Reason I'm asking about that is that I have no spare M42 adapters, but plenty of Pentax junk I could rip the mount off..)

Big Dave · 08-17-2008, 01:40 PM

You could use a K-mount bayonet quite easily, but you would need to calulate the thickness of the required shims. It is 2mm with my OM mounts. The mount would drilled using the OM mount as a guide. I did this with my Soligor 70-220 3.5 CD zoom. I glued three small 1/2mm thick washers under the mount. They required trimming to allow them to align with the mounting holes. It worked quite well, although there was a small gap which filled with black foam rubber. I wanted keep the original OM type mount in case I wanted to revert back to om. Remember that the mounting screws must be either counter sunk or flat type. The mount surface must be flush.

Dave

Originally Posted by pingflood

So an M42 adapter would be better/easier than trying to put a mount from a Pentax K-mount lens on it? (Reason I'm asking about that is that I have no spare M42 adapters, but plenty of Pentax junk I could rip the mount off..)

*pingflood* · 08-17-2008, 02:25 PM

Thanks for all the info. Will probably start the experiment on the 28/3.5 and if that works out just transfer the mount to the 50 (assuming that's doable). This is some pretty neat stuff!

Big Dave · 08-17-2008, 06:16 PM

I converted the 50/1.8 and the 24/2.8 and they both have the same mount. I beleive that all of the OM Zuiko's use the same mount, so switching it from one to another isn't an issue. The diaphram levers are slightly different. I tied the lever to a screw with a spring on the 50mm. The 24mm was restrained with a copper wire, which I like better and it was easier to do also.

Dave

Originally Posted by pingflood

Thanks for all the info. Will probably start the experiment on the 28/3.5 and if that works out just transfer the mount to the 50 (assuming that's doable). This is some pretty neat stuff!

wirrah · 01-04-2009, 03:56 PM

I use OM lenses on my *istD quite often but only for macro. I have the 80 and 150mm OM bellows macros. I built an adapter out of an OM extension tube and PK mount. This works well as these two macros require extension tubes even on an OM camera. As a result I can use all my OM macro kit on my Pentax.

I have several other Zuiko lenses but since I still use an OM2n I can't really modify the mounts. But the 200mm f/4 Zuiko makes an excellent macro on the Pentax.

As an aside the T1/T10/T8 ring flash systems work exceptionally well on the Pentax as well!

cheers

Greg