A and M.

Many of my posts to this forum, have been in the form of whines, whinges and even rants, about ebay. It has given me plenty of reason, but sometimes, I love it. Now, is one such time.
On Thursday evening, I spotted an M series 50mm f1.4, on a 'buy it now'. Sold as spares or repair, for... Well, I'm not gonna tell ya, but it was silly cheap! The fault?. A dented filter ring. Everything else described as ok. I grabbed it! The picture was awful, but I reasoned that even if it was in dreadful condition, it was worth the asking price.

It arrived this morning. I am a happy bunny! - The thing is pretty much mint, apart from the rim ding.

I have never had equivelent examples of A and M series lenses, at the same time before, so I was keen to compare the M, with my A 50 f1.4.
The M, is a little heavier than the A, but the biggest difference is build quality. The M seems to be better made. The finish makes the A look a bit... Well, cheap and plasticky, really. The M focusing action is smoother. Generally, It feels better put together than the A.
The lens coatings are different colours, but I do not expect to see any difference in image quality between the two, They being I think, identical in optical arrangement.

I am hoping that all the M series 50s shared the same front tube, so that I can pick up a scrap f2 for a fiver, and swap them over.

I picked up a couple of fungus-infected f2 for a fiver each a while back. Removed elements, cleaned, reassembled, and ended up with two near-mint lenses aside from a few dust specks!

Yes, the M series fifties are in plentiful supply, so hopefully in won't be too long before I find a cheap donor.

There's one on ebay for a tenner at the moment, may be more than you want to spend though!

You can take the dents out of filter rings, there's a guide on the web. Basically you cut a semicircular dent in the edge of a piece of wood that's wide enough to support the lens barrel, then form a similar shape in the end of another piece of wood. Now place the lens in the dent with the bent area against the wood, and use the second piece of wood along with a hammer to gently tap the filter ring back into shape. As you're not hitting the lens directly with the hammer you shouldn't have any problems with it slipping and doing more damage.

Thanks for that, Matt.
It's a good idea, but in this case, I don't think that method would work. The threads are compacted, too, so even if I could get the dent out, it still wouldn't be possible to get filters on. It would look ugly, too. - No, I think the best solution is a donor front tube. It is probably worth sacrificing a rough and cheap f2 to make the f1.4 look nice again, and it would probably add 20 or 30 quid to the value!

The annoying thing is, I had a shabby f2 M, last year, and gave it away!

The Dimitrov site lists two variants of the M 50mm f2 (and they do both exist, I have both). The earlier ones have a metal aperture ring, while the later ones have a plastic aperture ring and a linear aperture lever amongst other minor details. It seems as if Pentax wanted to make a final batch of M 50mm f2s so they adapted some parts from the A version, hence the plastic aperture ring (nothing like as nice to use as the metal one) and linear aperture.

If you come across one of the later ones don't use it as a parts donor, they seem a little more unusual. I've only seen one which I bought cheaply because the aperture ring didn't work too well, I managed to fix that and it's now on an MG (presumably the right age, as the MG was their final pre-A series body).