SDM Lenses

Just an aside I believe Olympus also use ring motors in their SWD lenses and they are not just reserved for the larger-longer focal length zooms. I can testify that they are blindingly quick, weather and dust sealed too.

George, I think you are correct regarding seals and focus motor capacity, it should make no difference as the seals do not offer any resistance to the motor (the mechanism is internal with respect to the seals).

I had the 50-135mm and the 60-250mm, the latter lens would benefit from a better motor, I can't comment on the 16-50mm as I've not used one, but in general the further the focusing parts move the stronger/faster the motor should be.
As for the other point, Nikon, I know on most of their bodies other than the cheapies, use a similar system to Pentax with a screw drive in the camera body, I had a D80.
So they will work with non motorised lenses with the right mount.
Canon on the other hand use only motors in the lenses, ever since they changed to the “EOS” mount.

George, I may well have this wrong but the cheaper Nikon bodies, D40, D60 etc. will only work with USM lenses. To keep the price low, they have no internal motors. The higher end cameras do have an internal motor, so work with all the lenses.

Their "screw drive" lenses are silly fast as well in 90% plus of the cases.

Regards

There are now two types of K mounts that use a SDM motor the KAF2 and KAF3. The KAF2 also has a screwdrive but KAF is SDM only so won't autofocus on non SDM cameras.

As for enabling KAF2 lenses to use screwdriver the answer is no.
The lens has a digital contact with his ID and info what the lens can, if the camera knows it has a SDM it will use that.
You might disable the digital-info contact but with that you will also lose the ability to autofocus since the AF lenses also has a Digital-info contact that gives the info it can autofocus.
It's a software thing so they could make an option in the menu maybe?

Did I now explain it too much or not?
Martin always blame me that I give too much information.

Neither does Pentax with the KAF3 mount and they have said that designing KAF2 is too expensive, complex and that KAF3 lenses can be make smaller and lighter.

So further DA* will probable not AF on non-SDM bodies.

ps. Sorry George, thought I had the right word (whining) ^^;

The K10D can be flashed back one version which was the firmware that enabled SDM on the body. This will allow it to use the DA* lenses that have screw drive ability to focus using this method only.

Good clarification Richard. I suspect that this is where a lot of people are getting confused.

Yes that's the one exception, I simply wished they had a menu option though

Here is one in action link
At least not one used in lenses but it works on the same principle.