Looking at their web site, the flash model I looked at ends AFD, not AFDP, are you adding the P, or is that the model number actually written on the flash.

Ordinarily I would expect the P to indicate Pentax fit (C=Canon, N=Nikon), but if it is actually written on the flash, maybe it is a P-TTL variant.

The visible flash through the viewfinder certainly makes it look as though it might be P-TTL capable but . . . it's more probable that you have the red-eye reduction mode set on the camera and it's that flash that you can see in the viewfinder.

Sounds interesting. You can easily see if it does P-TTL. Take a flash photo. If you see a preflash through the viewfinder before the mirror is raised, it's P-TTL capable.

EDIT: I just checked their website. It's listed as a TLL flash so you'll probably not see the pre-flash. This means you'll have to use it in manual mode on the K10D as the camera is not TTL enabled.

I saw only the DS references. I missed the reference to K100D, so it wasn't obvious to me, although it should have been.

It would be useful if you mention which body your post refers to. The latest firmware for all Pentax digital camera bodies is available here. The *istDS, referred to above, is up to version 2.02.

This is an untried method, but using basic science principals, it ought to work.

Place your film in a watertight container, then put that container in a watertight bag and bury the whole lot at least a foot (the deaper the better) deep in the sand. Mark the place you buried it and cover the area with one of those silver or gold survival blankets. If you have any waste water, wet the area.

The deaper it's buried, the cooler it will be.
The evaporation process will keep it cool.
The blanket will reflect the suns heat.
The marker will ensure you can find the film again after a sandstorm.

Alternatively, take a tree with you and leave the film in the shade of the tree. Easy really.

I have one of these ring flashes, bought from another forum member. It's a very good TTL/manual unit but needs to be used in manual mode on a K10D as the camera doesn't support any TTL flashes other than in manual mode. There is also a less powerful and less versatile AF-080C ring flash too. The Vivitar 6000AF (or something like that) is a cheaper option than the AF-080C

The original comes in its own case with 3 mounting rings to enable the flash to be fitted to 49, 52, and 58mm filter threaded lenses.

That advert states that it "clips on to the lens", which is untrue, it doesn't. The flash head clips to a mounting ring which is screwed onto the lens, without which it can't be fitted to any lens so be sure you get those too.

Thinking about it, it was a Tokina 350mm Mirror lens that I adjusted. I had to take it apart to clean the mirror surfaces and that's when I discovered this information.

You don't if it's within your acceptible limit. If you make the adjustment, it'll focus just a bit closer at the bottom end.

The focussing beyond infinity problem is very easy to fix. From memory (so you might not like to rely on it . . . I don't) there are three screws which hold the focussing barrel onto the focussing mechanism. Loosen them and adjust as necessary. If that's not exactly correct, and I can't check because I don't have mine any more, the procedure is very simple. Don't be afraid to loosen a few of the visible screws to fix the problem.

The Centon mirror lenses get mixed reviews, mostly unfavourable. If you really must try a 500mm mirror (or reflex) lens, at least try a decent'ish one. The Tamron BBAR 500mm f8 lens I had was a reasonable performer and is about as good as they get. I sold it only because I just wasn't using it. Pentax once made a 400-600mm reflex zoom but I haven't a clue how good or bad it is/was.