Yep, you must compose first, on tripod, focus should not be a problem, AF seems to work fine with IR on the K10D/K100D.
WB for best results, best to:
1) Fill your frame with green on a tripod - the greens must be grass/leaves in STRONG sunlight
2) Screw filter on
3) Dial in settings required for a properly exposed photograph (with the filter on, anyways, can always take a few test shots to get this)
4) Take custom WB
To PP in Photoshop, quite simple, but have to see what sort of WB you get first, Pentax so far doesn't really give the correct WB, which is why I always shoot in RAW, then select trees/leaves as grey point. If no trees/leaves then clouds will do.
In any case, you should get sepia toned images, you can leave it be, and to get a more duotone effect, can desaturate all blues using Hue/Saturation tool in PS. Then adjust Contrast/Shadows&Highlights to taste, pretty standard.
If you wish to get blue skies, then do an extra step anytime called a channel swap:
1) Open Channel Mixer
2) Red channel : Red 0 Green 0 Blue 100
3) Blue channel: Red 100 Green 0 Blue 0
4) Green channel: Red 50 Blue 50 Green 0 - this channel has more freedom, you can do whatever you want
If you do the channel mixer step before you desaturate the blues and don't wish to go back, you can now desaturate the reds/yellows.
It also depends a lot on what kind of IR you want, if you just want B&W, then can just desaturate and tone as per preference.
If you have any problems, feel free to post up your original image, I had experience shooting IR with improper WB (which is actually quite important) using my old Sony H2 in the past, so I can provide some alternatives to correcting IR images with improper WB. =)
Cheers! Glad to see one more IR person in Pentax. =)
