If you want a pocketable set up (ie. camera+lens around neck, one lens in its pouch in each pocket) then the DA12-24 is too chunky I'm afraid - I've tried it and it just doesn't want to go, even without the hood on. The D-FA100 (another excellent lens) is a bit of a tight fit too.

If travelling very light in such a way is what you have in mind, then I'd recommend you go for the DA35 (macro or non-macro), FA77 or DA70, and one of the DA15 or DA21. All those lenses are small, light and share a common 49mm filter.

If space isn't such an issue then I think the DA12-24 is well worth its place in any camera bag.

If you buy one of the Interslice camera seal replacement kits from eBay you get a sheet of the very thin felt that would have originally acted as the friction material inside the hood.

Very handsome lens anyway.

I've always harboured the suspicion that that was a secondary motive. The primary motive for the popularity of 85mm (and 105mm, 135mm and 180mm) lenses was that they were "standard" focal lengths in medium/large format equipment, hence the designs were already well proven and cheap to bring to market. Not that there's anything wrong with that of course...

It would be nice, but the advantage of using the built in flash is that the hardware is already built into the camera. To use a radio (or similar) system would mean using additional hardware expressly for that purpose which would add weight and cost - two things the average Pentax user is known to grumble about more often than not.

That is a possibility, but I wouldn't waste too much time trying to make a silk purse from a sow's ear if I were you - a Domiplan is never going to be winning awards for fidelity.

Assuming your friend's camera is an M42 mount then there are a couple of other lenses out there, that can be had for around £10, that would give much better IQ than the Domiplan. The first that springs to mind is the Helios-44 (Russian Biotar copy, supplied with various Zenit SLRs, 58mm f/2), the other is the Carl Zeiss Jena Tessar 50mm f/2.8 (usually one of the "budget" lenses on Praktica SLRs). For slightly more money (£15-20) he could have a Takumar 55mm f/1.8 or a Pentacon 50mm f/1.8.

If you're wondering what to buy him for Christmas this year then any of the above would work with his current body and offer a serious upgrade on the Domiplan.

It sounds like a success to me! Domiplans always did have a very poor reputation for IQ (hence them being so cheap) so I think your results are very much in line with how the lens performed when it was new.

I bet your friend will be chuffed anyway.

"I started playing double bass back in '76..."

I can't be specific as I've never tried dismantling a Domiplan, but you're right insofar as force is never the way.

As a general rule, when you get to a point where nothing else seems to come apart, turn the lens over and start from the other end. You'll probably find that once the front parts are removed you'll uncover further screws etc that will allow the rear to be disassembled.

This is another good reason to take notes and photos as you go along - it really helps avoid having any "spare parts" when you put it back together again.

One more: The blades are designed to run dry - the "oil" residue comes from the grease used on the helicoid which will deteriorate with age and run into the rest of the lens. Clean any remaining old grease from the helicoid with a tooth brush as you've got it in the bowl of soapy water - when you reassemble the lens just add a small amount of lithium grease (I use Halfords own brand) to the helicoid to give a smooth focussing action. No other lubricants are required within the lens.

As a quick addendum; do not attempt to take the iris blades out to clean. They are little more than foil and will bend when touched - once bent they are write offs. When these lenses were made the blades were assembled on a special jig and dropped in as a complete unit - without the special jig you have as much chance of making the iris whole again as you have rebuilding a cow from a hamburger. This is why you clean the whole aperture assembly as a complete unit.