I won't part with mine but I have the "A" version (so no AF) and it's a superb lens, at least on film.

Over £200 less just because it's a different colour.

An AA battery grip for the SFX and SFXn popped up on E-Bay for a reasonable price this morning so I grabbed that. They're quite hard to come by but, as long as you don't mind the extra weight of the AA batteries, they pay for themselves after a time because you don't need expensive lithium batteries. This will be the second one I own though I don't use the SFXn as much since I got a pair of Z1s (which don't have the AA option unfortunately).

I wouldn't have thought so. Don't put too much faith in patent applications - many such lenses are never produced. Pentax would need a lot more lenses than this for a mirrorless system.

The K 28mm f/3.5 is a really nice lens.

I posted a link last week to an M 120mm at WYC for half that price. 149 is too expensive, they usually go for around 100.

I've come across a few but never bought as they're too big and heavy.

Strange the Ricoh page doesn't include anything but wide-open close-ups. I'd have thought some street, cityscape and landscape photos would have been good to include for a lens like this.

Looks like a nice lens though and out to provide a nice alternative to the single big ultra-wide zoom.

First or all - have you tried giving the contacts a good clean on both lens and camera?

The only way to know if it's worth foxing or not is to get a quote. I'm not sure if places will charge just for that or provide one for free.

If you do replace it, I would recommend the Sigma 17-50/2.8 over the Tamron. Not because it's optically better but because it has a couple of advantages: it's better built and it has a built-in focus motor. It's also a bit heavier because of the more solid build and it's generally a bit more expensive, both new (if you can find it) and used. Sigma no longer make lenses for the K mount but there might be some new stock somewhere still.

I saw this while browsing and was surprised by the low price for this rare lens. It looks in the same condition as my copy but is significantly cheaper, I paid around 100 in 2017. This lens is much better than the M (or Takumar) 135mm f/3.5 but is about the same size and weight and a little faster. A good purchase for anyone who likes their manual lenses.

https://wycameras.com/collections/latest-stock/products/pentax-m-120mm-f-2-8-exc