I hadn't thought of that - sounds like a good option for plan B.

I've looked in to this, as I really fancy having a go with one of the early FD 85/1.2 SSCs on a Pentax but I don't think it's straightforward. Again the register distance is smaller, so you either need to move the glass back in the lens or take some metal off the lens mount.

Some of them also have 'floating' lens elements near the original mount which need to be moved if you do this. It's not impossible, but probably involves metalwork and optics beyond my skills at the moment - I think that the chances of unintentionally converting the FD lens into a paperweight are higher!

I've never had a Domiplan, but have been put off by their reputation. However, some of the other Meyer lenses are quite nice. I also have an Oreston 50/1.8, which is sharp from wide open and has rendering that I quite like. I've tried the Oreston 135/2.8 as well, which was OK, but nothing special (may have been a duff copy, as others seem to rave about them).

I've been after a Meyer Optik Orestor 100/2.8 for ages but had lost out a quite a few to the eBay snipers. A coupe of weeks ago, I found one in a lot with some other, random, fungus infested lenses and won it from a reasonable price.

What wasn't mentioned in the listing and I didn't spot from the poor photo was that it was an Exakta mount, not M42 (caveat emptor). On Exakta cameras, the lens mount is closer to the film/sensor plane than on M42 or PK mounts. This means that the lens would need to be mounted closer to the sensor than the PK mount to work on a Pentax DSLR without additional optical elements. However, I had a quick Google and it looked as if it should be possible to adapt it to an M42 mount without doing anything too drastic.

I thought it worth a quick write up here, as it turned out to be quite easy, non-destructive to the lens and well worth the effort.

From lurking over at mflenses.com, I know that Meyer Optik lenses, like Pentax SMC lenses are usually salvageable from fungus. It was pretty filthy when it arrived, but the optics cleaned up well, as did the outside:




The diaphragm was also stuck and needed cleaning up, which was a bit easier than the Takumars I have worked on (due to the lower build quality of the Meyer), but quite quite fiddly. The Oreston in Exakta mount has an auto/manual switch, meaning that the diaphragm can be used in stop down mode, ideal for use with an M42 adapter.

I bought a cheap m39 to m42 adapter (the type used to mount m39 lenses on m42 mount cameras), which is a snug fit over the Exakta bayonet mount:




After trial mounting it on a broken Spotmatic body I had lying around, to get the axial alignment right (so that the lens is the right way up when mounted on the camera) I glued it in position. Depending on what sort of glue you use, it can always be removed later to reverse the conversion.

The most complex part of the process was accommodating the difference of approx 0.75mm in register distance (lens mount to sensor plane) between the Exakta and M42 mounts. The glass needs to be moved nearer to the sensor in order to get infinity focus on an M42 mount.

There is provision for adjustment of the focus distance by slackening the screws holding the focus ring to the focussing helix and moving the ring to a new position. By doing this, calibrating for infinity focus by focussing on a far away object (I used a telegraph pole approx 100 meters away) with it mounted on the Spotmatic and then re-tightening the screws, I managed to adjust it enough to get infinity focus on the M42 mount.

I took a few shots with it this morning and am quite pleased with the initial results:

Shot @ f/2.8 (I think), JPEG striaght out of my K-m:



100% crop from the above:



It seems pretty sharp wide open with colours a bit more muted than Pentax glass, but not unpleasant.

I hadn't really intended to get in to doing mount conversions as I'm not fortunate enough to have access to machine tools, but it was a lot more straightforward than I thought it would be; the only tools I used were a screwdriver, a rubber sink plug (to remove the trim ring around the front element), a pen and some glue. No drilling or machining to the original lens in needed, so the conversion can be reversed to allow the lens to be used on an Exakta again should anyone want.

For Sale: Tamron Adaptall-2 SP 90mm 52BB f/2.5 macro lens (with 1:1 adapter and PK/A mount)

£130 including delivery to the UK.

Tidy and in good optical condition, but a 'user' rather than a mint collector's piece.

The focussing is smooth, the diaphragm snappy and the PK/A mount is in good condition and full working order. The glass is clean and clear, with a few spots of internal dust and a small mark to the coating of the rear element (shown in the photo below). The detent stops on the aperture ring are not very positive - I suspect that it has been modified for video use at some point, however, with the PK/A mount you do not need to use the aperture ring.

Cosmetically there are signs of light, careful use, with major scratches or scrapes.

I have recently bought a Kiron 105mm macro lens and also have a Takumar 100/4 and a Tamron 52B, so don't really need this one.

For sale my Samsung GX-10 (effectively a rebadged K10D).

It has under 6000 actuations (somewhere near 5600) and is in excellent condition. I bought it three months ago to see if the pentaprism viewfinder was a worthwhile upgrade over my K-m. It was, and although I've been very happy with it, it has cemented my decision to upgrade to a K-5.

Supplied with the following:
- Samsung 18-55 kit lens
- 2x Samsung branded battery packs
- Charger
- User manual
- Original packaging

£230 delivered within the UK

You have a PM

Interesting. The two Pentax lenses do look very similar. The Samyang wide open shot looks slightly front-focussed to me, even so it is remarkably sharp at f/1.4. I like its bokeh as well, although I prefer the more contrasty rendering of the Pentax lenses.

It would be interesting to see a 'bokeh' comaprison between the Samyang and Pentax lenses. If I get some time at the weekend, I'll have a play and see if I can work out how to do something approaching an objective comparison.

Interesting; the M120 fares pretty well too. It will be worth cheking back in to see if they have a chance to do the Bokeh shootout.

How about swapping the rear groups? I've taken my M28/2.8 apart to clean the diaphragm and it should be quite straightforward to change the rear group. From memory, I think you need to do something along the lines of the following:

- Remove the five screws from the flange on the mount.
- Lift mount off
- Use lens spanner to remove the rear group
- Replace rear group with non-fungus infected group from the donor lens
- Replace mount etc.

Best of luck

A bit of both for me, depending on the circumstance - f/2.8 AF zooms for general shooting or anything that moves quickly, but MF primes for low light, macro and portraiture.