[Christine Tham]

I don't see how this wouldn't be a firmware fix. The camera knows the EV, and it already has the capability for fine tuning AF on a per lens basis. Those 2 capabilities together add up to a pure software fix is my best guess, not additional hardware.

You may want to check the thread on Falk's paper over at Pentax News and Rumors.

My experiments today seem to indicate the issue is related to both EV and colour temperature of the light source.

I was able to get the camera to focus correctly when illuminated by a weak light, but to misfocus shooting directly at a yellowish light source.

It would also seem that stray light may or may not also influence the results.

If a firmware fix is possible, it now seems to be a complex fix (the camera need to take into account several variables, including brightness, light temperature, lens curvature, lens aperture, possibly even stray light) - based on Falk's results in conjunction with my relatively unscientific experiments and also input from another member (dlacouture).

My suspicion is that the issue is hardware, specifically the design of the AF module, together with lens type/model. This is not something that will be easy for Pentax to address, and appears to have more or less existed for several generations of cameras now (we now have people confirming similar issues on the K10D, K20D, K-7, K-x, K-r and the K-5) - perhaps the problem can be addressed in future models.

[twitch]

Yes but all those variables exist and are known by the body already at the time it is locking focus, and importantly the capability for adjusting AF according to lens exists. The hard bit would be the engineers coming up with the right AF adjustment value based on all those permutations.

[Christine Tham]

Yes but all those variables exist and are known by the body already at the time it is locking focus, and importantly the capability for adjusting AF according to lens exists. The hard bit would be the engineers coming up with the right AF adjustment value based on all those permutations.

Only some of those variables exist. Not sure the AF sensor is able to detect colour temperature, which seems to be a stronger variable than light level.

Another strong variable appears to be lens model. If the firmware fix exists, I am not sure it applies to non Pentax lenses.

The other factor is inconsistency - sometimes the camera focuses correctly, sometimes it does not.

[Smeggypants]

My K-5 misfocusses consistently in low light. I would dispute the findings of the above.

[Hound Tooth]

Pentax, like any other corporation, exists for one purpose only; to make money. They are going to do a cost/benefit analysis weighing several options. I suspect among them are developing a firmware fix, hardware fix, completely new model, and just ignoring the problem. Whichever one of those is going to result in the largest black number (or smallest red number) on the bottom line is what they will do.

Damn right! So the best way to speak is with your money. Stop buying Pentax gear until the problem is fixed. Discourage potential customers from buying a K-5 until the problem is fixed. Let everyone know about this problem until it's fixed.

Almost every shot at our family Christmas gathering is ruined because of this damn problem. It was to be my grandmother's last Christmas with her family (she's very ill and expected to pass away any day now). The camera was still new to me then. It was confirming focus on every shot. The images looked fine on the LCD screen. It wasn't until I got home that I realized almost all of them were out of focus. My family depended on me to save these memories for them, and I failed.

Do your friends a favor, don't let them buy a K-5 until Pentax takes its customers seriously.

[twitch]

I read FalconEyes paper and have more hope now that this is fixable by firmware. I hope I'm right.

[Hound Tooth]

(we now have people confirming similar issues on the K10D, K20D, K-7, K-x, K-r and the K-5)

Whatever, my K-7 never had this issue. I've got pictures from Christmas 2009 (K-7) and 2010 (K-5) to prove it. I was an SLR newbie on Christmas 2009, the K-7 was my first ever DSLR. And every one of those shots is in perfect focus under identical lighting conditions in the same home. Almost every shot from Christmas 2010 is out of focus, and I can easily confirm front focus in most situations by looking at where focus really did get achieved.

[loveisageless]

I'd be interested to know how all of this is sitting with Japanese owners of the K5. Even if Pentax ignores the rest of the world, the problems must be a topic of discussion among Japenese consumers. The home market may not leave Pentax any choice.

[Christine Tham]

I'd be interested to know how all of this is sitting with Japanese owners of the K5. Even if Pentax ignores the rest of the world, the problems must be a topic of discussion among Japenese consumers. The home market may not leave Pentax any choice.

I just did a Google search for "ペンタックス Ｋ－５ フォーカスス" (Pentax K-5 focus), did not see many relevant hits

One of the hits was a blog article with a link back to this forum to a thread about how good the K-5 focuses in bad lighting!:
http://informationondigitalcamera.blogspot.com/2010/12/pentax-k-5-continous-focus-in-bad.html

A potential explanation for the lack of hits: In Japan, most indoor locations are brightly lit using flourescent lighting - perhaps it would not be common to shoot in dim yellowish lighting?

[jolepp]

Only some of those variables exist. Not sure the AF sensor is able to detect colour temperature, which seems to be a stronger variable than light level.
...

I understand the '+' in 'SAFOX+' is supposed stand for a wavelength (~color temp) sensor. Actually it could be this failing to give a correct reading or maybe failing to apply the correction when in lowish tungsten light. This is speculation as much as anything, but it would fit the circumstances (in which case the firmware might do better by just not trying to apply a correction under an intensity threshold).

[Class A]

I own a bicycle shop. I actually don't care all that much about bicycles, but I have become quite fond of eating regularly and living indoors.

It would be better for you and your customers if you sold something you deeply care about. It is not always possible to work in an ideal place where one can self-actualise oneself to the benefit of everyone, but AFAIC, on should strive for getting there.

In the case of a publicly traded corporation such as Hoya, they have to act in the best interest of their shareholders.

You might be right, but this is just wrong, AFAIC. If a company neglects its customers in favour of its shareholders, it will have to pay the price sooner or later. Or, the customers deserve the products they buy. Count me out from buying products from a company that puts the shareholder first.

My K5 arrived yesterday and test shots showed a consistent spot that dust mapping did not reveal. Using my blower did not dislodge it. I sent it back to B&H today.

Did you note down the serial number?
In any such case, the serial number should go into the forum serial number database. It is useful to check whether one has received an item with a known track record as well.

Can we say zero resale value on the K5?

Yes, please send it to me for $0. I'll pay for the shipping.

[NaClH2O]

My K-5 misfocusses consistently in low light. I would dispute the findings of the above.

But doesn't that make it inconsistant? I'm not trying to be funny or confrontational here, but if Christine gets different results than you, the the results are inconsistant, even if your camera exhibits consistant results

NaCl(if hers does x and yours does y than the results are inconsistant)H2O

[Rupert]

Almost as bad as the FF issue, for me, is the loss of confidence in Pentax. It is not too late, but the clock is ticking. This will have a severe adverse effect on models to come if not addressed, and on the Brand in general. I can see a greatly reduced "first adopter" crowd on the next model if there is no remedy for this and other noted problems. Many of us are still here, still hopeful, and still willing to spend our cash with Pentax, now and in the future. The ball is indeed in Pentax's court. If I was capable, what I would do does not matter....what Pentax does will matter for a long time.
Regards

[Smeggypants]

But doesn't that make it inconsistant? I'm not trying to be funny or confrontational here, but if Christine gets different results than you, the the results are inconsistant, even if your camera exhibits consistant results

NaCl(if hers does x and yours does y than the results are inconsistant)H2O

I was talking about a single copy of the camera being concistent. The behaviour of various models of camera do apear to behave differently, but until we get some proper data comparing several models this would only be an assumption.

I've seen people post pictures 'proving' their K-5 is OK, but the pcitures were at EV levels of 4, 5 and above. I've also seen people claiming their K-5 is OK, but after Falc posted his findings all of a sudden their K-5 exhibited the problem. So with that in mind unless scientific tests are done to remove the quirks of human personality then it's all assumption and hearsay

[Smeggypants]

Almost as bad as the FF issue, for me, is the loss of confidence in Pentax. It is not too late, but the clock is ticking. This will have a severe adverse effect on models to come if not addressed, and on the Brand in general. I can see a greatly reduced "first adopter" crowd on the next model if there is no remedy for this and other noted problems. Many of us are still here, still hopeful, and still willing to spend our cash with Pentax, now and in the future. The ball is indeed in Pentax's court. If I was capable, what I would do does not matter....what Pentax does will matter for a long time.
Regards

I purposely didn't becuase a 'very first' adopter. I was glad I did as I miss the sensor stain issue. But I was an early adopter ( early January 2011 ) and got stung by this FF problem. I found the problem within 2 hours of owning the camera, before even logging into any pentax forums and find others had it