K20d AF error

<p>I recently got (partially) over an error with the exposure meter of my K20d (see forum thread: odd K20d light meter). I now have a new problem. When I focus the image, it comes out misfocused. When I use the AF indicator, it looks misfocused in composition, but is fine on the tail end. It all started after I tried to remove a pesky speck of dust that was between the focusing screen and the prism. I had to remove the focusing screen. Obviously (or so it would appear) I replaced it incorrectly. Could someone tell me where the side tag goes relative to the tray? (or further details if deemed necessary)</p>

The tab should be on your right as you look into the lens mount.

 

Three other things to check - have you secured the screen carrier properly, have you changed the eyepiece dioptre setting, and have you lost the shim that goes in before the focussing screen?

<p>I know this will sound stupid, but what in the world s a phim?</p>

<p>Also: there was only one piece that came out when I ejected the carrier.</p>

<p>And, Yes I have the Diopter adjusted properly.<br>

And, Yes I have 20:20 vision.</p>

<p>Peter,<br>

There is a shim between the prism housing and the focusing screen. There are different thicknesses of them and this shim perfectly aligns the distances necessary for the AF array to match the prism based manual focus array. The precise thickness is matched to your exact camera. If the shim fell out, your AF system would function normally, but the prism wouldn't look correct.</p>

<p>I recently dealt with this subject on my K10D, hence the knowledge. It sucks, but you can try using other objects to shim the screen, like duct tape, masking tape, or other means. If you use masking tape, use thin strips of the blue painter's tape... it comes off easier.<br>

OR<br>

Order new shims. Somewhere on Pentax Forums someone asked about the shims and later on the post the part numbers were listed.</p>

<p>Good Luck.</p>

<p>Peter,<br>

If you don't have the Pentax K20 user manual, it is <a href="http://www.pentaximaging.com/files/scms_docs/K20D_Manual.pdf">here</a>.<br>

I found great visually oriented focusing screen installation <a href="http://www.katzeyeoptics.com/files/install5.pdf">instructions</a> from Katzeye when I ordered my replacement screen from them a few years ago. While they are specific to their own product, the install approach is the same as with the standard Pentax screen.</p>

<p>Some Pentax bodies require a screen shim for accuracy in focusing. My K20D does not--or I just never noticed it--anyway I've installed a couple of screens in my Pentax DSLRs and have had zero problems. It's just tedious and potentially dirty.</p>

<p>ME</p>

<p>You were right. I just had it in backwards.<br>

Thank you</p>