We expect AF to be perfect, but it's not. It is often better than our own eyes, but it's not perfect.

It's just part of the photographic technique to know the limitations of equipment and work around it.

AS long as you stick to facts and don't say libellous things you can name a case of bad service as much as a case of good service.

Billy, let me clarify that there can only be seconds between shots that do and do not work when this fault, and it is a fault, develops. It's either a user-remedied cleaning or, if not, then a more serious repair to the stop down mechanism.

When I experienced it getting gradually worse, then a switch off and on again sometimes cleared it, and then eventually did not.

If it's a chargeable repair, then I would delay until it becomes regular enough for you to be sure that the technician will actually find a fault. Intermittent faults can be very difficult to find and you can be almost certain that when it arrives at the repair station it will switch on and work perfectly.

OK, that's fine. The new shot I would have give +0.5 or +1EV to the exposure to compensate for all that white, but that's by the by.

My theory is that for some reason there was an intermittent electronic contact that fooled the camera and made it expose at full aperture, hence the vast over-exposure of yesterday's shot. Removing and replacing the lens could be enough to dislodge whatever it was and restore function.

I very rarely clean the lens and body contacts, but they do pick up a coating with time and need an occasional wipe. I do clean by a dry wipe any new lens or body to ensure there's no manufacturing film of grease on it.

I have had this happen to my K10D and eventually it developed into a fault that needed repair. Cost was £60 + VAT.

JP Service Solutions is the official repair facility in the UK. They are not overly expensive, but can be quite slow.

I've just had a look through the images and it's interesting that quite a few are shot with Pentax compacts. That's actually quite heartening as it means that no-one is excluded from the competition because they don't have a DSLR.

It's also interesting that it's not really possible to spot the compact shots from the DSLR ones. It's clearly the image that counts.

Love that first picture!

Yes indeed, payments can be reversed, although I'm not sure about gifts. In any event buying items and paying by eBay gift is contrary to their terms and conditions.

If it's local area, what's wrong with cash?

We await tomorrow's image, which may clear up the issues involved.

Peter, the shot can be taken before the SR has stabilised, but the metering is fast enough to measure flash output, so I doubt that can be beaten by the speed of a fingertip.

The OP states above that he checked and cleaned both the camera and lens electronic contacts, which doesn't tie up with using a K or M lens. There seem to be a number of inexplicable contradictions in what is going on here.

Can you confirm what lens was actually used when this problem was experienced?

Afterthought: was it taken in a blizzard or on a sunny day? Both have been mentioned.