Yes. I researched the market quite carefully before buying into a digital system; Pentax was best for my needs then and it still is - no regrets here

I could write a book on all the equipment that (with the benefit of hindsight) I regret not buying, but the only outfit I really regret selling was my Rollei 3003.

I had the body, two backs, two finders and three Zeiss lenses which I part exchanged against a Leica M6 for a £450 discount. The Rolleis are almost impossible to come by these days and fetch big money when they do.

I never did really get on with the Leica and only ran a couple of rolls of film through it before selling it (some years later) to buy my K10D and my first Pentax lenses so I suppose there's a sort of silver lining there...

But everything in my house is now very neatly labelled...

Buy an original Pentax adapter. I have one genuine one and three third-party (cheap) ones, the cheap ones have a habit of sticking inside the lens mount which can then mean several minutes with tweezers trying to remove them. They also have a nasty, scratchy quality to them whereas the genuine adapter always mounts and dismounts perfectly.

With the benefit of hindsight I would just buy the genuine adapter and ignore the cheap copies - none of them (the cheap ones) now get used and so they've proved to be a false economy.

If you speak to SRS I'm sure you'll find they're more than happy to mail items to Sweden.

One of my all-time favourite lenses and one of the best 135mm's ever made in my opinion.

As for price, I've seen quite a few selling around the £60-80 mark recently but if you're patient then you should be able to get one for less than this; I'd say around £35-50 would be about right for a good example. Try and find one that finishes on a Sunday afternoon as all my bargain buys come on Sundays when there are fewer last-minute bidders around.

Is it worth it? Yes! But watch out for sticking apertures (ask the seller if the blades snap in and out of position easily). These can be fixed (I've mended a couple now) but it's time consuming and quite tricky so better to pay a little more for a fully working one.

You won't be disappointed with the image quality!

I will (not least because Praktica cameras and Zeiss lenses were never made at the same plant, nor were they ever part of the same company. Also the Western Zeiss didn't have their own foundry and couldn't produce glass).

But yes, we're straying way off the path here so we'll save this for another day...

As far as I know Hasselblads have always used glass from Jena - the lens bodies may have been assembled in the West but I'm not 100% sure whereabouts (Zeiss have had almost as many assembly plants as they've had changes of name).

Even on larger formats though you never see Planars above 100mm so I wonder if there's some physical reason for this? Sonnars can't work below 85mm on SLR's because at shorter focal lengths they project back too far and would foul the mirror (hence the 50mm's etc are rangefinders and compacts only) - perhaps there's a similar (albeit reversed) situation with Planars?

I've had five of them now and the one I've ended up keeping (purely because it was in the best condition) dates from 1984.

As for not putting them in the same category as Western Zeiss I'd agree - by and large the Eastern lenses are far superior! Up until the end of WWII *all* Zeiss lenses came from Jena, after the war (and the setting up of what I tend to call the "Fake Zeiss" in the West) Jena still supplied Zeiss Ikon with all their optics until well into the 1960's, after which Fake Zeiss contracted out production to mainly far eastern manufacturers (currently Cosina for 35mm/digital lenses but many others have been involved). Now we've come full circle and Zeiss is all one big happy family again based in... Jena! Where it always has been to be honest.

I've got a Planar (a 50mm though, never seen a 135mm Planar) and while it's technically a better lens it doesn't have the Sonnar magic either. Again it's a bit like the difference between my D-FA100 and my FA77; the macro is sharper, more even and more neutral (more perfect!) but the FA77 just has a certain something that can occasionally make your jaw drop - the macro is too perfectly sterile to ever really do this IMHO.

Still, each to their own and if I'm going to wish for a new Pentax lens then I want a 135mm with a small element at the front, a small element at the back and a big fat chunk of glass in the middle - that seems to do the job very nicely!

I am talking elements/groups but the CZJ 135/3.5 Sonnar is a 4 in 3. You can see the optical formula here.

The original "Olympic" 180/2.8 Sonnar is a 5 in 3 (link to schema) and the (much later designed) 200/2.8 Sonnar is a 6 in 4 (link to schema).

Whilst the 135 and 180 classic 3-group designs are considered highly desireable, it's no great to suprise to see the 200/2.8's going relatively cheaply as they just don't have that Sonnar look. Don't get me started on the Vario-Sonnars...

Too big, too heavy, results similar to slightly longer versions of my D-FA100 whereas the Sonnar gives "magical" results more like a longer FA77.

Because I buy and sell a lot of lenses I've had the opportunity to try several (10+) different 135mm designs on the K10D, including some Pentax ones, but nothing touches the Sonnar. The only one that has come close was the Pentax M135/3.5 (which is probably as near as Pentax have come to making a Sonnar design being 4 in 4 - the "real thing" being 4 in 3).

Not only are the results great but the Sonnar also touches on my sweet spots for size, weight and handling (slightly longer than a FA77 but with the same slide out hood design and 49mm filters). The only things I'd change (and this is what I'd want a Pentax version to address) would be a K-mount so I didn't have to fiddle with adapters, AF with QuickShift for when I'm feeling lazy and a focus ring that turns the same way as all my Pentax lenses!

Yes, I think it probably would be