Photoshop Elements 7 will do the job for you at a modest price.

I agree with iceblinker's assessment. Pentax AF is fine as far as I'm concerned - it snaps cleanly into focus on most subjects, hunts rarely, sometimes has a problem but then so do they all.

The final fine adjustment manually via the manual focus ring is superb and makes use of AF in many close up shots actually very efficient.

There is not normally any detrimental effect.

I would check the dioptre setting by aiming the camera at a blank wall or sky and adjusting the viewfinder until the etched lines on the screen are sharpest. Then you are focusing your eye on the screen with your eye at comfortable rest.

You might be straining with a basically misadjusted viewfinder and your eye is taking a while to readjust afterwards.

Having said that, if you have a problem with your eye the first person to see is your optician or doctor or both just to check it out.

Interfit do a home studio kit at £299 that looks fine. Then you only need a background.

Interesting point about screen brightness - many people who use Beattie screens actually find them brighter but harder to focus accurately.

Absolutely not a problem. Sometimes the system is fooled by something and we just have to reframe a little and try again.

I've recently purchased a copy of Photoshop Elements 7 (for teaching purposes) and it's very very good. It has most of the features of the CS range and works in a very similar way to Photoshop 7.

Well worth £53 from Amazon.

Autofocus is not infallible.

You can see in the viewfinder whether or not you are focused correctly, so with practice you shouldn't miss many.

If the image is sharp on the focusing screen but not on the sensor, then there is a misalignment of the two. Have you cleaned the mirror, the focusing screen or changed the focusing screen? These things should never be touched unless you have the correct equipment and knowledge.

Alternatively, the dioptre setting on the viewfinder may not be adjusted properly and your eye is not focusing at rest. Point the camera at a blank wall or sky and adjust the dioptre until the etched lines on the focusing screen are sharpest. The lens does not even have to be in focus whilst you do this.

The final thought is camera movement. Are you using a solid tripod? If not, you will be wavering backwards and forwards more than enough to change the point of focus.

It is also readily available for Pentax K mount as well. I suggest you contact SRB Film Services, who supply every conceivable adapter. Those they don't supply they can make for you.