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.

This may sound like sacriledge to a Nikon user, but it would be much more convenient to sell the Nikkors on eBay, for which you might get a surprisingly good price, and then look at buying a selection of used Pentax lenses from the same source.

It would make the photography so much easier...

If you are conscious that your images could be sharper there are two things I would suggest. Firstly, using a tripod when shutter speeds become slower or when using longer lenses in all but the brightest light will make the most dramatic difference to sharpness. Using your longer lens with hand held shutter speeds of less than 1/500 sec will almost certainly compromise sharpness. Also, using medium apertures will give the best optical results from the lens (maybe f8-f11) which will make camera shake more likely, so again use a tripod.

Secondly, if you are really critical beyond this, then a better lens is the next step. Although, for example, the 18-55mm is very good at smaller apertures (a bit soft wide open) the 16-45mm is better and will give you a distinct step upwards in quality.

There are other factors in sharpness, such as using the lowest ISO setting on the camera and even the sort of subjects you take, but hopefully the above will be helpful.

Nope, totally unbelievable...

We have both of these and they do the job well:

SMC Pentax-DA 50-200mm
SMC Pentax FAJ 75-300mm

With the latter lens the long end is a whopping 450mm-equivalent, so watch out for camera shake. A sturdy tripod is needed.

I suspect that the percentage of camera buyers that actually read these reviews is actually quite small. Probably most people just go into a shop and buy what they fancy at the time, or what the sales person directs them to.

If this is so, then the impact of magazine reviews might be only significant for a particular segment of the market place.

No doubt someone somewhere has the statistics for this.

George

You said something very interesting in this thread about a Sigma 50-200mm AF lens. I had one of these recently in Minolta fit, but without any electrical contacts on the mount how does it focus exactly?

Three AAA batteries were housed in the body of the lens as you say, and it was a monster. Not much good on my pentax cameras though!

What can you tell me about it?

Just over the East Lancs Road from where I live! Hope you had a good day.

If you join the Pentax user Club the latest magazine has an article all about the current lenses.

Briefly, you can use any Pentax bayonet mount lenses with an "A" setting on the aperture ring or later ones with no aperture ring. (You can use earlier ones too with some loss of function, but I don't want to complicate this unnecessarily for you)

Manual focus lenses will be SMC Pentax-A

Autofocus lenses will be:
SMC Pentax-F
SMC Pentax-FA
SMC Pentax-FAJ
SMC Pentax D-FA

All the above will be suitable for film and digital cameras.

For digital SLRs only the range is:
SMC Pentax-DA
This means they are designed to only cover the area of the CCD, which is smaller than 35mm film so the lenses can be more compact. They are also specifically designed for digital, so may perform better than some film lenses, but I wouldn't worry too much about that.

As for the letters:
SMC = Super Multi Coated
ED = Extralow dispersion glass
IF = Internal focusing
AL = Aspherical element

Yes, it's a minefield, but the simple thing is to start with the pentax kit lens and see how you go with that. After a short while you may feel the need for a wider or longer lens and i would still look at the Pentax range.

Hope that helps a bit!

Correct, but it's also important to remember that once you have downloaded your images and backed them up, when you want to delete them from the card format the card in the camera. Deleting and formatting from the computer can cause problems.