[dseang]

I have been experiencing strange, sporadic, auto-focus behaviour, and wonder if
a) anybody else is experiencing this;
b) this is normal behaviour for the DL2 and,
c) if I should take the camera back to the shop.

Problem is as follows:
1. I half-press the shutter and wait for AF to lock-on and the green hexagon to light, in the normal manner;
2. A very instant before I press the shutter all the way down, the AF disengages (or the green light goes out, at any rate) and the shutter will not release.

At this point, I can do one of two things: go back to step one and try again (it often takes 3 or 4 attempts), or I can just keep the button mashed down, hoping, eternally hoping, that the AF will lock on again and the exposure will be made, which (sometimes) happens in about a second or so. Clearly, this is not what I bought a DSLR for!

Incidentally, I found a work-around which involves setting the 'OK' button to activate AF - in this mode the AF is normally disabled, and the shutter release works instantly. However, it's an extra step to remember, requires a bit of manual dexterity, and is extremely taxing on the old carpal tunnel. Passers-by often direct puzzled glances towards my wierdly contorted right hand while I'm shooting...

Any advice appreciated - thanks in advance,
Sean

[roscot]

Just a couple of questions and possibilities.

1. Does it happen with a particular lens, or any lens?
2. What are the light conditions when this happens?
3. What kind of batteries are you using?
4. What AF mode are you using?

The DS/DL series is known to have some issues locking focus in lower light conditions with darker lenses. If you have faster lenses, see if you get the same behavior with them.

NiMH batteries that are somewhat discharged can generate some less than ideal AF behavior. Try Lithium AAs or CRV3s and see if you get the same behavior.

Try using the center AF sensor only.

If none of this helps, or your problems are more random in nature, you may have a camera problem, and it should be checked out.

[dseang]

The problem seems to be lens- & battery charge- agnostic.
Lighting - typically indoors, with bounce or off-camera flash. I haven't been shooting outdoors a great deal recently.
AF mode - AF-S, typically spot sensor.

Bear in mind that the problem is not the typical DL/DS slow or 'hunting' AF - in this case the AF is locking on in a reasonable amount of time (relatively speaking ;-) and then disengaging *while the shutter release is held halfway down*. I believe the default behaviour on most DSLRs and other types of camera is for AF, once engaged, to remain locked until the shutter button is released - nicht wahr?

[roscot]

Hmmm.... given that the AF-S/AF-C selector is menu/software driven rather than a switich, I wonder if the camera is "falling out" of AF-S some how and the camera is getting confused. Anyway, sounds like a camera problem. Perhaps you should have Pentax take a look at it.

[dseang]

Or better still - I got one of those 3-year insurance thingies when I bought the camera - so if I can persuade some Jessops guy that it's malfunctioning, I walk home with a K110D... :-)