OK. Thanks Pete. I took most of the above as read (same as my camera). The explanation of the first question is clear now. As I said, I assume that my camera at present "presses" the shutter to maintain focus.

Interestingly, the reason I do not use AF-C on the one I have now is that it is genuinely continuous. All the time. If you listen carefully, you can here it zip zip zip all the time. That's why I avoid it, to save battery and prevent useless wear. I wish it was as you describe.

I really should get to a shop and try one, I know. Trouble is I am a fair way away from such a shop and when I go into town there are a dozen "real" errands to do.

Nick

[There are two separate issues here. One is whether refocusing is required after zooming. It is in some cases, not in others in practice.]

If it's arbitrary, to me that means it will be needed.If I don't know, I assume the worst case, I guess.

[The other question is whether the AF works while you are zooming. The answer to that is yes, but zooming doesn't make AF-S refocus once it has already focused.]

Sorry, I am completely confused. What do you mean by "the AF works while zooming", if it's not re-focusing when I zoom? Are you referring to AF-C?

As far as my plans go, I am not sure. I am still tossing up whether I can _justify_ the jump to DSLR. I know all the reasons. It's just justifying it. I am also trying to work out whether a DSLR will have enough extra photographic features to make it worth it. The S100FS has problems, but it's a pretty powerful camera.

Ahhhh....OK. I did a lot of SLR work in film, but all my stuff was totally manual. However I just tried my old Tokina 50-250 on my old film camera, and it definitely needs re-focusing. Is it later (D?)SLR stuff that is as you say?

Sorry. Not just arguing. Technology moves so fast....I went from SLR to non-DSLR for several years, and it's all got away from me.I am great at photographic theory, but fings 'as changed!

EDIT: I did read in a review of my camera that it was a problem because you had to re-focus. What I did not realise was that it may have been compliment to the camera (badly written) in that it took care of this.

Thanks Pete.

I am not quite sure what you are saying. Sorry.

When you say AF is not affected by zooming, do you mean it stays in focus as you zoom?

My present non-DSLR camera (Fuji s100FS) will maintain AF when I zoom, even when in AF-S mode.

As I zoom I hear the AF working, and the image re-focuses.

Does the K20D do this, either with body-driven lenses or in-lens AF drive?

Thanks for any advice

Nick