K110D AF Back Focus - All Lenses

Hi Team!

I used both the Nikon (booooo) and Pentax (yea!) focusing charts to check out the Auto Focus on my K110D. Used a whole whack of AF lenses, including my 31mm Ltd.

The tests were shot initially wide open (Max aperture) on each lens.

All results had major back focusing issues which only began to somewhat resolve at f8 or smaller apertures. At least the center line was in focus. Oh, yeah - it's bad!

As this problem is constant no matter which lens I use, may I conclude that the camera body internals are off?

Now, I'm just about to install a Katz-eye split image focusing screen, when I get the courage, and as I look through the very detailed instructions I see a shim which is located between the prism housing and the screen - all held in place by a hinged clip.

Is it possible that this shim is the incorrect thickness? I'd like to think that, but when I manually focus - everything is sharp as a tack, making me believe that the focusing screen's position HAS to be 100%.

Now my poor head hurts......

Would love any ideas!

Cheers and have a great day!

AF accuracy has nothing to do with the focusing screen. In fact AF still works even without a screen fitted.

You need to examine the photographs rather than the viewfinder image to check AF accuracy. If it is consistently wrong with all lenses, you may be able to fix the problem by altering a "secret" setting in the camera, if your camera has such a setting. I don't know for the K110D.

Focusing screen: I didn't know that the K110D requires a shim for a Katz Eye. THe K10D doesn't. Anyway it should be correctly aligned if when manually focusing, the image in the viewfinder is sharp AND the photograph is sharp.

Sounds to me like you need to get a tune up (better be under warrenty) from pentax!
Hope they fix it quickly for ya' Mac!
We're gonna take some pics together this summer!

Pete,

Thanks for clearing that up!

Hey Don,

Pete says I can run around blind with no screen and the camera on AF - that way all my shots will be surprises (and probably better than what I'm getting when I actually try!)
I'll save that for when you come down. You like stuff like that. Otherwise, I was planning to use YOUR gear!

Pete, the shim is already there in the factory install - not supplied by Katz-eye. Looks like all K110D's must have one as it shows in the Katz-eye installation manual for K110D, K100D and K200 models.

Now to screw up the courage to actually install it.

Oh, and the photos bear out what I see in the viewfinder - AF backfocused, manual dead-on. There is quite a change when I switch from AF to Man and back. Very audible and visible.

Meanwhile - good ol' f8 will have to get me by until I find that "secret" setting which probably only exists for K10's and K20's.

Thanks again!

Secret setting = Debug Menu. K110D does have one. See http://www.google.co.uk/search?hl=en&q=k110d+debug+menu&meta=

Good luck with the blind photography

Ohhh Pete!

You know I'm just crazy enough to try this!

Did you read the last post in that thread about what Pentax said?

All who enter here - at your own risk!

(follow me)

I'll let you know. This is either going to work or I'm looking for a K20.

I'm not convinced the info in that post is correct. I think the K20D is the only Pentax model to have multiple AF settings for multiple lenses. Certainly with the K10D and *ist DS, the same setting is applied to any AF lens.

Anyway, there's no harm in having a go as long as you return the settings to what they were originally if things go funny. You've got to live dangerously sometimes

Update.

I haven't had time to actually change any values yet, but the directions in your post work with a K110D, Pete!

(And I actually managed to get out without anything blowing up!)

When I get some time I'll go back in and run some tests.

Thanks,

OH MY!!!!!!!!

What a difference!

I've maxed the forward focus and it appears to be dead center now with my 31mm Ltd set at f1.8.

I'll put my other AF lenses on later to see if this correction is consistant across the board, but the 31mm is the best lens I own and I one I really care about the most. I used to leave the Av at f8, now I'm gonna run around at f1.8, and really use this lens properly.

Thanks for the tip, Pete.

Reminder to everyone - "at your own risk".

The Last Post.

Tried my other AF lenses.

Same improvement!

It's like I have a whole new kit!

To tell you how bad this backward focusing problem was - from day one, I couldn't get my zoom lenses to autofocus on infinity when set to wide angle (the green pentagram indicator would just flash, and I'd have to go to manual focus to force the shutter to fire).

No longer!

I'm delighted!

Thanks!!!

Well done. You have done what a Pentax service engineer would have done in a fraction of the time for none of the cost!

And all thanks to my good friend, Pete!

I owe ya, Buddy!