PENTAX PK SMCM 135MM F3.5
They are pretty common as they date from the time when 28/50/135 was a common trio of lenses so don't pay over the odds for it.
K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
My website
I got mine for £20 and have used it on both my DSLRs.
Can't confirm what Kris says about the 2.5 version though, they seem pretty scarce.
Cheers, HG
K110+DA40, K200+DA35, K3 and a bag of lenses, bodies and other bits.
Mustn't forget the Zenits, or folders, or...

I've some gallerieshere CLICKY LINK! and my PPG entries.
Here is one taken with mine

Peter
My Flickr page
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
My website
I find stop down metering is accurate down to about f11, go below that and it starts underexposing badly although you can easily meter at f8 then use a bit of simple calculation to set the shutter speed for smaller apertures.
I don't have the 135mm from the K series but I do have the 120mm f2.8, which is a very nice lens indeed. Smooth and solid as all K series and with a nicely unusual focal length.
Matt
Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
Ian
on my K7 it meters well without much intervention, its certainly sharper than my 50-150 2.8 Sigma
all the best.
albert
I didn't originally realise that we were talking about the M version as opposed to the K, which is a much larger lens.
Matt
Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
philstaff
Member
Ian