Camera focus problems.

[Greenly]

Thank you for alowing me to join this group. I am using a Pentax K20d and believe I have a back focus problem with two of my lenses. Could anyone give me some simple and straight forward advise as to the most efficient method of establishing if there is a problem and if so how to fix it.
Thanks

[MarkW]

Whilst this site is written about the Nikon D70, it can equally be applied to any camera model or brand. If your camera is back or forward focusing then you need to get the camera or lens (most likely camera) recalibrated by the manufacturer.

http://focustestchart.com/chart.html

Note - This is general advice - I shoot Nikon not Pentax

[Topgunn]

I am pretty sure the K20D has an option that you can adjust the focus on different lenses. I think it is custom menu 35 or something like that from memory. If you are going to adjust it I would use a focus chart and maybe a moiré pattern. There is plenty of info on The PentaxForums (http://www.pentaxforums.com) about this. I had a BF problem with my camera but had to use a hack to fix it. I think all of the big players have adjustable AF now. Just make sure you do heaps and heaps of test shots to make sure its not user or environment error aswell as test it "In the real world" and remember Pentax cameras front focus under tungsten light so avoid doing the tests under those conditions.

Edit: This page should help you (http://www.pentaxforums.com/forums/pentax-dslr-articles/61385-autofocus-adjustment-hints.html) :)

[kiwi]

Chuck it and get a Nikon :)

Is that helpful ?

[arthurking83]

(without the benefit of knowing what lenses)
If the lenses in question are zoom lenses, you may be making things worse by using the focus adjustment feature in camera. Best used for prime lenses only.

[Topgunn]

Im pretty sure the camera remembers what lens is attached so if you adjust the focus with a zoom lens on, the adjustments made are only for that lens and the adjustments are easily undone. So it doesnt hurt to try anyway.
When I adjusted my camera I didnt have that luxury and my adjustments were "global"
But it was my prime with its wafer thin DOF that emphasised my BF problem. I reeled off hundreds of shots before and after the adjustments with all of my lenses at all focal lengths and apertures up to f6 in both test conditions and in real shooting conditions and Im very happy with how it is now. I understand what your saying though and I did base most of my testing on my prime.