35mm film lenses and DSLR's

Pentax-M lenses are fully manual, so you will need to set the aperture on the lens and then use green button stop down metering to set exposure before you shoot.

Not sure what you mean by Pentax S lenses, perhaps you mean Pentax-A? Those ones are also manual focus, but auto aperture so you can use the camera in AV (and other) modes. These are easier to use on DSLRs (but still manual focus).

Pentax F, FA and DA are autofocus lenses.

Pentax S? Never heard about it, but it could be screw mount. That's an old format that you can still use but only with a converter and with limited functionality. Some fine glass around, though.

Pentax M is the more recent mount - you can mount the lens directly but no AF and metering requires some work.

I would look for Pentax A (pk-a). The A-50mm f1.7 or f2.0 are fine lenses that can be had for very little money. No AF on "A" lenses, but metering works.

In general, any Pentax lens which is actually badged "Pentax" will fit and work with varying degrees of functionality. That goes from the original SMC Pentax range of the 1970s through to the present day.

The earlier M42 screw mount (badged Takumar) are great lenses but need an adapter to work on DSLRs, try to get a genuine one as 3rd party versions aren't usually as well made. Personally I keep them on the Spotmatic/SV as my K-m's light meter doesn't seem fond of them.

If there's a specific Takumar you like the look of then look for the SMC Pentax (not -M or -A, just SMC Pentax) version as these are effectively SMC Takumars with a K mount and need no adapter.

You might also see "Takumar Bayonet" - these were Pentax resurrecting the Takumar name on cheap lenses. They have a K mount as the bayonet name suggests but lack SMC coatings, so in my experience aren't as vibrant as other Pentax K mount lenses. There were also a few Pentax-badged lenses (all zooms IIRC) without SMC coatings which have similar problems. Just look for SMC on the lens body and you won't be wasting your money.

The only SMC Pentax lens to avoid is the F 35-80mm, it's slow, soft, and generally not very nice. The earlier F 35-70mm is equally compact but a lot better if you're after something in that focal range.

As others have mentioned, the differences between M and A lenses really boils down to ease/convenience of use; so to answer the other part of your question:


No, not really. You may find reports where someone claims that the M version of this or the A version of that is better, but as a rule this is probably no more than sample variation and the way the particular lens has been handled/stored these last few decades.

For the sake of convenience and compatability stick to the A series, but if a really nice M comes around at a good price (and you're happy to work fully manually) then you won't be losing out in terms of image quality.

Also worth a look for the older SMC Pentax 55mm (f1.8 or f2, they're the same lens but the f2 has a baffle to stop the aperture opening as wide) if you fancy a manual prime. These make brilliant short telephotos on digital and are incredibly sharp. Not as easy to find as the M 50mm f1.7 but if you see one cheaply then go for it.

You may also find that you can get hold of an old 50mm more cheaply by buying something like an ME Super/MV1 with one attached.

Just about all old Primes can be great with digital. You may not get the sharpness, resolution or contrast as modern digital designed aspherical lenses, but don't let that put you off. Old lenses can, and are, great fun to use. They give you a different effect that you could not get with modern glass. There are people out there who are using 1930's Leica lenses (with adapter) on micro 4/3rds cameras and getting wonderful results.

As for the K-mount takumar, yes they don't have multi coating, but again they can be great fun to use. I have the 135mm f2.5 and I love it for certain things.

Best thing with photography is to have fun and experiment. If you buy and old lens for £20 and find it is not what you want, you can sell it again for £20.

Hope this helps.