How, specifically, do the green mode pictures you've taken suggest the AF isn't working?

I'd suggest the following things to try in the first instance:

First, check that AF-S works, using:

- the camera on a tripod,
- centre AF point selected
- pointing at something stationary, flat and contrasty.
- good light on the subject
- manual exposure, so you can be sure of consistent shutter speeds
- 2s delay mode, to eliminate shake

Ideally, use the chart from here, mounted flat, tilted at 45 degrees away from the camera, so that you can establish whether the picture is all out of focus, or if there is a part of it that's sharp.

Then, if the results are sharp, try switching to AF-C, again as above.

If it's still Ok, try AF-C with a very slowly moving target.

As I say, a properly functioning K10D's AF system should be perfectly capable of getting slowish moving gliders sharp. It's either technique, or it's not working properly.

This, for instance, was AF-C, probably going a bit faster than the glider.

If the AF system is at fault, it should be very easy to prove it, reliably and repeatably.

Not sure what you're getting at with this point, sorry.

[quote="El Dingo"]It is important to switch the SR to off when on a tripod (now I'm not suggesting for one minute...:blush - I wonder if this could affect the results if SR was left on? I suppose it depends on how the SR moves the sensor...:[/quote]SR is off with all the remote and delayed modes, regardless of the position of the SR switch, so I can't see how SR is at all relevant here.

From the EXIF, the shutter speed was 1/3000s at F8, so SR would be irrelevant.

It's just out of focus, I think. Aircraft in flight take practice.

Personally, I find the K10D's AF-C adequate for aircraft, especially when tracking left to right so that the distance from the camera isn't changing all that fast (at least compared with when they're heading directly for you).

It's the only situation in which I switch the AF-point selector to Auto, since if you use the centre point only, you have to be able to point the camera extremely accurately as you track the aircraft. Otherwise, it can lose focus very easily and hunt around dreadfully.

The other thing about AF-C is that, unlike AF-S, it will take the picture whether it has focus lock or not.

The number of mAh refers to the capacity in milli-Amp hours, not the voltage, so the only difference between cells of 2450 and 2500 mAh (all other things being equal) would be an approximately 2% difference in the number of flashes (or pictures) you'd get out of them.

I doubt you'd notice the difference, and there are other more relevant considerations anyway, not least the self-discharge rate when not in use.

I've moved over to low-self-discharge AA cells for my flashguns. They have a lower capacity than the highest capacity Ni-MH cells available, but they keep their charge when not in use for a long time.

Brands available include Eneloop, Hybrio, Panasonic Infinium - all broadly similar AFAIK. I use the Infiniums - only 2100 mAh, but at least I don't come back to them and find them completely dead after a couple of weeks.

Well it does, yes, which is why you want to be sure that it focuses where you think it does, and not an inch or so behind that.

That's why I went looking for AF issues at F1.4. With the exceptionally shallow DOF you might expect that you'd see back or front focusing that was masked by a deeper DOF with other lenses, or the same lens at narrower apertures.

It wasn't a surprise to find some, and it wasn't a surprise to see it go away at F2.

What was a surprise, was that taking out the adjustment I'd just put in to cure it did not put back the BF I'd seen originally.

It's a bit like it would be a surprise, if you wore glasses for five minutes to cure an obvious short-sightedness, then took them off and discovered that your uncorrected vision was now perfect.

I had a very strange experience with the AF adjustment on my K10D that I can neither explain, nor replicate.

As some may have noted, I acquired an FA50 1.4 in excellent condition recently from another forum member, and the first thing I did with it was an AF check, since I have nothing else as fast as 1.4.

I found what appeared to be significant back focusing, detectable at F1.4 but not at F2 or beyond. So I adjusted the AF (40 um required) using the debug menu, and this cured the problem.

I then checked it with one of my other lenses, and didn't notice any change, but for some reason felt uneasy, and undid the adjustment with a view to repeating the process.

Rechecking the AF at F1.4 this time showed no back focus at all, and equally I couldn't see any with a couple of other lenses. Having used the FA50 for real now, a couple of times, I have no reason to think there's anything the matter with it.

Now I know all about the "dismantle, clean, reassemble" technique for miraculously fixing unexplained problems with all kinds of devices, but doing, and then undoing an AF adjustment to cure a problem, does seem a bit strange to me.

It was all on a tripod, 2s delay, green hexagon focus confirmation, centre AF point selected and all that... so no obvious reason for completely cocking up the initial check, and since I tend to work on the assumption that unreproducible problems don't exist, at least until they become reproducible, I'm not overly troubled about it.

I report it just in case it rings a bell with anyone.

It's not in the K10D manual.

There are lots of details at PentaxForums.com... in particular this thread, and this one.

There's an English version of the program that lets you connect to the camera over USB and set/unset debug mode. It's location is given here. Obviously, own risk and all that - but I've tried it and it does work.

Once you get into debug mode, the AF adjustment instructions are here.

Note that unlike the later cameras, there's only one adjustment on the K10D, which presumably applies to all lenses. So it would be worth checking that fixing the AF for one lens doesn't mess it up for others.

Edit: Peter's links have much of this information - the PentaxForums threads seem to be somewhat, maybe largely derived from them.

I bought an A-400mm F5.6 from a forum member, and I've been very pleased with it. It's heavy, though, and takes practice to get good results with.

I took this, and this with it.

Lens still for sale!

Just in case there's any confusion, the item for sale is the SMC-A 50mm F1.7.

This is a manual focus lens, not AF. With the aperture ring set to A, all the auto-exposure modes are available on the Pentax dSLRs, since the camera sets the aperture.

The reference to the FA50 in my OP was that it was what I used on the K10D to take some of the pictures of the item with.

Apologies for any ambiguity.

I think it's horses for courses, really. Tripods don't help for anything moving, unless you know for certain where something will be. They also don't help for anything transient, again, unless you know for certain where (and when) it will be, and often they're completely impractical to lug around. Fine if you have the time and energy, but I often don't.

Aeroplanes in flight and candids are among my favourite subjects, and a tripod is a complete waste of time for these. Much more important is an ability to see predictively, so that's what I tend to work on most.

But I've also been taking photos of gear for eBay auctions a lot recently, and as John says, the tripod is essential for the long exposures needed for the tiny apertures required to get everything sharp.