[wlachan]

Is a misaligned focus point indicator (the red rectangle that lights up on the focus screen) the same thing as front/back focus? My K10D with a Katz Eye clearly shows that the focus point indicator is above the center line of the focus screen. However, testing with a focus chart shows that the AF sensor itself seems to be aligned correctly with the center line. Against a focus chart, this causes a front focus problem if I select what I'm focusing on using the lit focus point.

The red indicator emitter is located on the forehead of the prism while the AF module is underneath the mirror box. They are 2 seperate devices and work independently. That means the red indicators have no effect on AF accuracy whatsoever. It merely tells you which AF point(s) has/have been chosen.

[pentkon52]

I sent mine in this week for same re-calibration issue. No experience with the DL, but I do have my original DS (sold it to my bro) back in my hands until then. Love the smallness of this little marvel; especially given how "bulky" my K10 has become with grip attached.

When i finally figured oy my K10D had BF problems i sent it in late Feb. Got it back last week, and did the same tests and it was doing the same things.
It went back in Monday.

It could not understand why my macro and closeup wide open shots were nice and crisp with the D2H, D200 etc but not with the K10D.

I see why now.

Hopfully they get it right this time. I know others on another list have sent theirs in and are happy with the repair. I'm not. Sorta like they just wrapped it up and sent it back thinking i would not check it

Dave

Dave

I'm one of the guys who currently has his K10D in the "shop" for back focus issues. I guess my question, at this point, is how in the world is it possible that so many of us are experiencing this difficulty? Are we talking about wear and tear, quality control problem, or maybe even a design flaw?

[reknelb]

I'm another with the K10d in the shop for back focus repair. They acted like I was crazy when I said this is a common problem with the K10D. I'm hoping that my camera comes back working properly. If it doesnt, I am seriously going to consider selling everything and jumping to a C#$%n 5D. Only problem is I'll be selling 3 bodies to get 1. We'll see, I should be getting it back within a week or so.

[aleonx3]

I'm one of the guys who currently has his K10D in the "shop" for back focus issues. I guess my question, at this point, is how in the world is it possible that so many of us are experiencing this difficulty? Are we talking about wear and tear, quality control problem, or maybe even a design flaw?

How long have you had your K10D? I got mine in Jan 08 (manufacture date 2007-10-14), and I have not noticed any BF problem so far (crossed my fingers). Could it be just the first few versions or simply poor QC? Mine also says model revision 2.1. GL..

[christinelandon]

Alfred, where'd you look to find your K10D's date of manufacture and revision numbers? Anyway, I got mine in late December '07 and, like yours, mine shows no evidence of FF/BF problems with either of the lenses I've got so far.

[pentkon52]

I'm one of the guys who currently has his K10D in the "shop" for back focus issues. I guess my question, at this point, is how in the world is it possible that so many of us are experiencing this difficulty? Are we talking about wear and tear, quality control problem, or maybe even a design flaw?

Not sure. I noticed my wider shots and macros were not quite right, from the start. I just put it off to me and or well not sure what else.

Thinking that, if Pentax made lens focus adjustment available to the user on the K20D, it might be design problems.

The Nikon D1 had BF issues in lower light, and Nikon said there was not a problem, but, if you sent it in they fixed it.

F stops from F 4 and up are not my problem areas. F4 to F1.8 are. No point in doing focus bracketing, a $1000 camera should work.:-)

I shoot a lot of indoor horse shows at ISO 1000-1250 at F3.2 or 2.8 with a D2H or D1H,and the focus is great. I wanted to start doing this with the K10D and a fast zoom. I'm not so sure now.

Or, i'm just part of the paranoid groups now.

Dave

Dave

[reknelb]

I just checked on my camera and it was shipped back to me yesterday. Here are a couple shots taken with mine before I sent it out with a sigma 70-200mm f2.8 lens.
The first one is at f5.6, the second at f4.5, both with shutter speeds of 1/400 at 70mm. The subjects are clearly in the middle of the shot and check out how the grass behind them is really sharp. The subjects seem to be in focus but, if you look closely they are just a touch off. If I had tried to take those shots at 2.8 or 4.0 even, I think they would not be in focus at all.

[wlachan]

If the problem presists after calibration in the debug mode (probably what most service centers did), then it may be a good idea to adjust the actual AF module phyically underneath the mirror box and get it as accurate as it can be (reset um to 0 first). The um setting in the debug mode should be used as fine tuning. But if the actual AF sensor was too far off, "I believe" there will always be some lenses not AF accurately while others are fine. This is probably the reason the cameras were designed to memorize individual settings for compensations.

[nostatic]

My new 31ltd showed up yesterday and I'm having AF problems with it. The problem is that my 16-45, 50-135*, and 77ltd all AF perfectly (well, as perfect as Pentax can ). I tried the in-camera AF adjust and it didn't really solve it. It just seems inconsistent. I can get it to focus sometimes under certain conditions, and other times not.

[aleonx3]

Alfred, where'd you look to find your K10D's date of manufacture and revision numbers? Anyway, I got mine in late December '07 and, like yours, mine shows no evidence of FF/BF problems with either of the lenses I've got so far.

Christine, you can find out the manufacture date, revision number and shutter count using PhotoME software which is a free download (use Google). Simply take a picture using the camera and then open the JPEG file, all the information about the image and the camera are displayed.

If the K10D is discontinued at the end of 07, then mine is probably close to the last few batches in the production process (last production date is probably Dec-07). Hopefully, the FF/BF problems showing up in the early production would have been corrected - keeping my fingers crossed (I tried the test using the Tim jackson focus chart and the result seems to be consistent with what I expected unless my test methodology was inaccurate).

[RiceHigh]

It has been re-confirmed that by a Pentax user who has a K10D, K100D and K20D that the K10D has different amount of BF/FF depending on lens model in use and the colour of the light source (whilst it seems that the K20D has got the former long-lasting problem resolved). Whilst you may set your body to adapt certain lens under certain condition to get proper focus under the secret menu, there is no generic setting which you can always get sharp focus, with the K10D. The following reports of mine maybe useful to you:

The user's experiment and posted test samples:
RiceHigh's Pentax Blog: Improved AF Accuracy of the K20D (Under White Lights Only)

The limitations of the (old) Pentax "SAFOX VIII" AF system:
RiceHigh's Pentax Blog: AF Accuracy's Dependency on Lenses and Yellow Light

How to adjust for AF system BF/FF errors (via firmware or hardware):
RiceHigh's Pentax Blog: Focus Calibrations for (Pentax) (D)SLR Bodies and Lenses

The secret engineering/servicing mode of the K10D:
RiceHigh's Pentax Blog: Secret Firmware Menu of the K10D (V1.10)

The method to revert back to the K10D firmware 1.10 for focus offset adjustment:
RiceHigh's Pentax Blog: How to Get Back to an Older Version of the Firmware?

Hope all these could help.

P.S. Have you got the K20D yet? Which *might* solve your faced problem.

I've had my K10D for almost a year now. After getting the 31mm Limited lens, I thought that I had a bad copy of this lens. Not so. I tried my 35mm and another wide lens and found that the point of focus was pretty far behind the target.

At 35mm, wide open, it is noticable. With the 31mm, wide open, it is bad. The reason that I hadn't noticed it sooner, was that in order to see this problem, the lens had to have a narrow DOF to make it obvious. At f/4 or f/5.6 the DOF was masking it.

Another thing that I noticed is that it gets worse, as the lens gets wider. It is fine at 50, bad at 35, really bad at 31, and I thought that I had a bad copy of a 14mm last month and sent it back!! All the time it was my K10D.

I read somewhere that this is a software calibration issue. That the K10D can be calibrated at several focal lengths for autofocus.

I am thankful that I found this out before the warranty ran out! I cannot afford the K20D for a while, but now I know why they added the "lens self-calibration" feature in it. I would bet that this is a "known" issue, and that Pentax has a lot of cameras coming back under warranty for mis-calibration.

I am sending my K10D back on Monday. I purchased a used *isd DL to get me by until the K10D gets back from Colorado.

Does anyone use the *ist DL as a primary or backup? How do you like it?


Sample "back-focus" photo:

The point of focus is on the bird feeder. I have also done the paper test at 45 degrees. This photo isn't an anomaly.

[alex1962]

In Romania, to Pentax dealer Focus94.ro | Magazin foto, aparate foto digitale the guy from service affirm that tested some K10d and they observed that customer update firmware to 1.3 says his camera have back or front focus. The guys from service have detection file data in Eprom is writting with errors. They say that resolvable is rewritting the firmware.
My apology for my english !

The original romanian text , from their site, is :
"K10D si FW 1.3
17 Martie 2008

Din testele facute de noi, la unele aparate K10D la care s-a facut upgrade de FW de catre utilizator am observat ca datele din Eprom sunt scrise cu eroare. In aceasta situatie e posibil sa apara back sau front focus.
Verificarea acesta o facem gratuit si putem sa instalam FW 1.3 fara eroare incepand cu saptamana viitoare."

Have a nice day,
Alex

[twinda1]

The red indicator emitter is located on the forehead of the prism while the AF module is underneath the mirror box. They are 2 seperate devices and work independently. That means the red indicators have no effect on AF accuracy whatsoever. It merely tells you which AF point(s) has/have been chosen.

But if you're using the red indictor to actually align the focus point, if the red indicator is slightly off, won't you be visually focusing on one thing, while the camera is actually focusing on something else? It's precisely that these are two separate devices and working independently that it's a problem when they are not completely aligned. However, this might only be an issue when shooting a focus chart at 45 degrees, as precise focusing is much more important at this fine scale.

[wlachan]

But if you're using the red indictor to actually align the focus point, if the red indicator is slightly off, won't you be visually focusing on one thing, while the camera is actually focusing on something else? It's precisely that these are two separate devices and working independently that it's a problem when they are not completely aligned. However, this might only be an issue when shooting a focus chart at 45 degrees, as precise focusing is much more important at this fine scale.

The red indicators are nothing more than telling you which point has been chosen. It has never been a precise instrument even if perfectly aligned to the focus screen and the AF sensors because each of the 11 AF sensors covers a much larger area than the indicator indicates. In practice, if precise AF is required, one might test each AF sensor and plot the actual coverage. It is then you might actually know what the camera sees and predict how it will behave. Ideally Pentax should made this info public but I am not aware of it. Also worth to know is that all Pentax DSLR bodies from the cheapest to the most expensive model employed the same design and assembling method. That means the more expensive K10D/K20D are no more precise than the cheaper models (although some would like to imagine they were).

As to those 45 degree tests being conducted at closeup distance, I myself are not fond of them and there are better ways to test AF accuracy. But if one must use them, at least give enough buffer area instead of assuming what the camera might see.