Exactly, which is why the "35mm equivalent" is quoted a lot, so we have some frame of reference.

The pentax DA digital lenses are also different in that they only have an image circle that covers the size of the sensor - used on a 35mm body the corners would vignette. This might, of course, be a useful effect on occasion!

The reduced image circle means the lenses can be more compact, and it might also mean that the lens specifications can be more ambitious whilst retaining high image quality.

I'm just coming to terms with the lens, which seems to be very well made indeed. optical quality - not thoroughly tested yet, but initial results seem very good.

I suppose it is very, very compact, and that could be a bonus. If the image quality is exceptional as well, it could be an alternative to the 43mm on those grounds, but much smaller.

To be honest, I just love lenses!

I see there's an announcement from Pentax about a new pancake lens, designed for the *istD and *istDS cameras. It looks very interesting, apparently it is part of the Limited series.

Have a look at the ePHOTOzine site for more info.

The facility to use the aperture ring is inbuilt into the *istDS and has to be enabled in the appropriate menu.

Superb lens, beautifully made, very robust and well worth the money IMHO!

It is nice to have new lenses, isn't it?

Have fun with it when it arrives...

Glad to hear the process of elimination is working out!

You can get the lens you want new, and I think it will cost around £170. It is listed by some of the suppliers advertising in AMATEUR PHOTOGRAPHER.

The SMC Pentax-FA lens is autofocus, but it does have a manual focus ring that you can use if you wish.

The SMC Pentax-A lenses are manual focus and are available in f1.2, f1.4, f1.7 and f2 versions. The f1.2 will be very expensive.

The optical design of all these lenses is very similar, and all will give excellent results.

Only you can decide the best compromise between cost and lens speed, but personally I have never really found anything faster than f1.7 or f2 to be any necessity. The cost of these lenses will be relatively low.

If you are buying on eBay I would wait for a mint example at the right price. The specific Pentax clip on lens hood would be a nice thing to have as well.

SMC (Super-Multi-Coated) Pentax lenses with suffixes such as -F and -FA will be autofocus and suitable for your needs. There are f1.7 and f1.4 versions and I would suggest they will be better than the Sigma lenses.

Macro lenses are also available in 50mm, but are usually f2.8 or even f4 but very highly corrected for closer work and giving magnification down to 1:2 (a 1cm long item will be 0.5cm on the film) or even 1:1 (that same 1cm item would be 1cm long on the film). I still believe that the Pentax ones will be better.

For a lens used mainly for Macro work I am not convinced that you need autofocus, in fact it is a nuiscance. So you could think about a manual focus macro lens which would be labelled SMC Pentax, SMC Pentax-M or if you want auto aperture operation, SMC Pentax-A