[Gator]

When focusing you're looking at the image made on the focusing screen, not the sensor, unless you're using live-view. You want the distance between the mirror and the image on the focusing screen to be equal to the distance between the mirror and the sensor. If something's off by a fraction of a millimeter, you'll get out-of-focus shots.

perfect explanation thanks

[rjsd]

Thanks for the pictures it realy helped me complete the adjustment process.

Thanks..

[Alfie]

The focusing screen sits in a hinged tray that is held in place by a retaining latch. Disengaging it will allow you to take out the washer (shim). The washer (shim) sits between the focusing screen and the penta-prism.

As usual with a KatzEye I needed a thinner shim. Availability in Austria: nil. I could only order the entire set from Germany for the bargain of 60 (!) Euros.

In the meantime I removed the original shim and fiddled around with three layers of PostIt which worked fairly good. After six (!) weeks of waiting I wanted to install one of the thinner shims. Unfortunately I cannot remember how I disengaged the retaining latch in the first place. Pushing upwards (= towards the pentaprism like the latch for the focusing screen) didn't work. Now I'm lost - any suggestions?

Edit: Mission accomplished. The latch is the small black part at the right side in the red rectangle in your image. The actual retainer is the silver part left to it. If the shim is in place it covers the retainer. Now push the black latch upwards and the shim will slide behind the retainer; release the black latch to fix the shim in place.

[stormtech]

Very nice guide. I think this should be available in the Pentax DSLR Article section so it is easy to find. A lot of folks want to change their focusing screens, but are a bit afraid as to how to perform the change plus the possibility of needed to change the shim for readjustment.

Maybe a moderator can copy this post to the article section?
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