What lens type retains ALL DS2 functionality?

I'm new to Pentax and have a DS2 with 18-55 and 50-200 kit lenses.

I'd like to consider buying a fast prime to use in low light - probably 35 or 50mm (50 and 75 after considering crop factor).

I'm confused, though, as to what type/series/fit of lens to look for that will retain all the functionality that I get from the kit lenses.

Can someone explain what I should be looking for? And has anyone got any specific suggestions for a cheapish solution, maybe to purchase on Ebay?

Any help would be much appreciated.

John

Somebody will correct me if I have got anything wrong:

All except the first series of AF lenses are identical in terms of the features they offer when used with your camera body.

That means FA, DA, FAJ, D-FA lenses are effectively the same as far as you are concerned.

The first AF lenses, designated SMC Pentax-F, send slightly less information to the body, and may therefore offer slightly less functionality. The emphasis is on "may" and "slightly".

"May" because I am not sure whether the DS2 can in fact use the additional information (I have the *ist D), and "slightly" because the reduced functionality is in practice so insignificant that I personally have never noticed it.

Some F lenses are in fact better in terms of usability than later lenses. If you have a chance to buy the SMC Pentax-F* 1:4.5 300mm, for example, snap it up. It comes with a superb tripod-mount cum handle, whereas the optically identical FA version does not.

F lenses can be more strongly built than FA and later lenses, and optically they are mostly identical. The only exception I know of is the 28mm lenses, where the FA is superior to the F.

Because the pixels in a digital sensor are slightly recessed, it is possible to experience some problems with lenses which transmit the light to the sensor at more than a slight angle. DA and D-FA lenses have been designed to minimise this problem, but in practice it's not usually an issue.

The FA 24mm has been mentioned as a lens which suffers slightly in this regard, and serious pixel-peepers claim to notice problems with other lenses. Personally, I prefer to look at pictures rather than pixels.

The moral of the story is that there is no need to worry about the suffix (unless you buy an old film body, in which case the FAJ lenses may not work with it, and the DA certainly won't).

Aside from the 300mm mentioned above, I have the F 1:1.4 50mm, the lovely F 1:4.5-5.6 70-210mm zoom, and the F 1:2.8 135mm. All are excellent.

By the way, the * in F* and FA* lenses denotes a lens of exceptional optical quality and construction (and cost! ).

And to answer your last question, the SMC Pentax-F 1:1.7 50mm is superb and probably the best value AF prime you can buy. On Ebay, you might get one for around £60.00.

Good luck.

G

I would echo what George has said. If you want an autofocus lens, then any Pentax AF lens will do just fine. The *istDS has the KAF mount, which differs from the KAF2 mount in that it does not support the Power Zoom function on a very few lenses that have it. No big deal really.

If you want any of the manual focus lenses (perhaps a macro) then the SMC Pentax-A series will be fully useable without restriction.

Earlier K and M series lenses can be used with restirctions, and even screw mount M42 lenses via an adapter but, again, with restrictions.

Interesting. Am I to assume that the SMC Pentax-A series are only manual focus?

As I mentioned previously, I think I'd like a fast prime lens but I'd also want it to autofocus.

Can someone tell me what small primes have autofocus?

Thanks

Yes.

Any of the AF lenses that have a single focal length only, that is, are not zooms, are called primes. Small ones could be anything in the standard or wide angle ranges, but telephotos might be quite bulky. Obviously it depends on how you define small, but Pentax lenses in general do tend to be quite compact compared to other marques.

Don't forget the new DA series digital-only lens range which has quite a few prime lenses that are very compact indeed. As the DA lenses are designed to cover the area of the CCD only they can be made much smaller than would otherwise be the case.

50mm mf prime
+
1.7 af teleconverter
=
85mm portrait lens
*
1.5 mag for digital body
=
127.5 Af portrait lens!!!!

John

I would reccomend you seriously consider manual focus if you can, KA lenses are pretty reasonable, you could be lucky enough to pick up a 50mm f1.7 for £30+ whereas a KAF prime will set you back a few hundred quid or more, its not that long ago I sold a K mount 50mmF1.7 and 135mm f2.8? (or was it f3.5)...worst thing I ever did despite the lack of functiuonallity on my D, as soon as I have the cost of the K10D covered I will be looking to replace both of those with KA equivelents.