Focus problem in MF

Hi. Lately I've been working more and more wiht MF lenses on my K10D and I'm noticing that the focus is off. I hadn't really noticed it before, but lately its quite apparent.
Do I have to send it to Pentax (and do I do that?) or is it something I can fix by myself?

Thanks

Seems a common problem with all DSLR's. Just not made to the same standards that the old SLR's were. Do a search on Google. Lot of info on Rice Highs site.

shim

Do you've adjusted the diopter correctly?
point the camera at a blank wall and adjust the diopter till you can read the the information/camera settings clearly.

Do you mean:

1. Photo is out of focus when image appears in focus through the viewfinder (on the focusing screen)?

2. Photo is out of focus when the focus indicator (green hexagon) indicates that the image is in focus?

3. Something else?

The focus indicator comes up, it seems focused to me (although I do wear glasses and really need the diopter adjustment.
It doesnt focus on the spot it should.

I'll do some shots to show with different lenses.

For some subjects, the focus indicator will be inaccurate and then you can focus better by ignoring it. The image should be sharp though when it is sharp on the viewfinder.

There could be some misalignment with the focusing screen, AF system or sensor, but then I would expect the problem with AF as well as MF lenses.

So I don't know what the problem is. Double check the diopter adjustment (and maybe even your glasses prescription) and keep practising and experimenting with MF. I think that'll be more fruitful than sending the camera back. Good luck.

I think the focus indicator does a pretty good job when it beeps (just some time it doesn't beep...)
I checked my diopter, its correct. I checked my decision against focus detector... same result:

With SMC-A 50mm F1.7 @F2 (I believe) trying to focus on the "78".



With the Tokina SD 70-210mm F4-5.6 @F4 trying to focus on the "0.5"



You can see its focusing in front of what it should. Not a very exact test though, no 45 degree angle and they were hand-held. But that's beside the point... It shouldn't do that should it?

If the "78" in your first example was sharp in the viewfinfer then something in the camera is misaligned. I'm not sure whether that would be the focusing screen, or the sensor, or possibly both.

It's probably happening with any AF lenses you have as well, but it isn't so noticeable with slower lenses that give a greater depth-of-field.

But if the "78" was not sharp in the viewfinder then you've simply got to turn the focusing ring until it is sharp, ignoring the camera's focus indicators. (The green hexagon is the main focus indicator, by the way).

I'm thinking you are right about the misalignments. I hadn't use anything very fast in AF, and certainly not close (shallower DoF).
Although it puzzles me why it would be wrong if in the viewfinder it shows up correctly... Is the viewfinder at a different distance than it should be from the mirror?

The focus indicator and me seem to agree, so no problem there.

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.

What I find odd about this is that yours focuses in front whereas mine focuses behind. If it was a common manufacturing fault I would have expected it to be all in the same direction. All you can do is bracket a few shots at different distances. It's not too bad if it's always in front. I use a focusing rack so if it's critical I can focus take a shot move back 10mm and take another.... pain in the ass really, almost makes the camera unusable. Alternatively use a small f stop.

I don't have any problems with the *ist DS which has a different screen. I'm not sure if they are interchangeable.

Canon have a couple of special screens for their cameras that are supposed to improve manual focusing. One of the problems was that to improve brightness they had cut extra grooves in the original screens beyond what you would normally have in a fresnel lens and this threw the optical image out of position.

shim

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

The focusing screen, or the sensor, or both, could be too far back or forwards.

(Sorry I never remember which way round it is for front-focusing).

First I would check that the focusing screen is seated properly - by flipping the tray down and back up.

Video: http://www.youtube.com/watch?v=YqZCjT-jr1s

Yes, they are.

EDIT: Please see my reply below.

I always thought they were, but there's a tutorial on the web of someone putting an MX screen in a K10 and he found the DL screen to be bigger so possibly the DS and DL aren't the same size. link1 and link2

shim