Pentax A 100 mm

The A version is much rarer than the M version, but whether or not it's worth that price depends on what the buyer is prepared to pay. I wouldn't pay that, but a mint example of the lens would definitely be worth having.

I have the M version and it is one of my favourite lenses but I am fairly sure I wouldn't spend that much for the A version. Having said that, old Pentax glass is commanding higher and higher prices. Just have a look at any of the 85mm offerings, M42 or K mount.

K.

Strange thing is that the M version goes for buttons usually
under £100 which for that lens is the lowest it's ever been.
The big advantage is that it's tiny compared to a 135mm and
also very sharp.

I would have expected AF for £262

That's somewhat amazing - the M 100mm (both the f2.8 and the f4 Macro) seem to be going for very silly money. I've even seen people trying (and presumably succeeding) in getting £80 or so for examples with optical faults such as fungus or fogging. I'd love one of each but until I see them for slightly more sensible money I won't be buying.

The A could well have been fought over by collectors. You could almost buy a D FA 100mm Macro for that much!

If you can live without the benfits of the "A" setting then the M series lenses offer superb value and quality. As for the 100mm A f2.8, I believe this is one of Pentax most under-rated lenses, probably because it lived in the shadow of the 85mm A f1.4. I owned one briefly many years ago and have recently re-acquired one - it retains the spirit of Pentax lens design from that era - quality, size and smooth. I don't think I'd pay above £200, but a mint one maybe

I have never seen a M 100mm 'f2.8'. the most of M are f/4 version and therefore goes a lot cheaper than f2.8. i think Pentax made three extraordinary A macro lenses, A 100/2.8, A 50/2.8, A* 200/4. A 50/2.8 seems not rare and cheaper than other two.

Just to clarify this, the lenses are:

SMC Pentax-M 100mm f2.8
SMC Pentax-M 100mm f4 Macro

The former is a standard telephoto, focusing to 3 feet. The latter is a macro lens, focusing to a magnification of 1:2, or half life size.

yes, i did miss a macro after M 100mm f2.8. So there is no Pentax M 100mm f2.8 macro.

Correct. We have to wait for the A series, when the choice becomes:

SMC Pentax-A 100mm f4 Macro
SMC Pentax-A 100mm f2.8 Macro
SMC Pentax-A 100mm Dental Macro (I think this is the f2.8 version), with additional markings to aid dental photography.