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01-24-2011, 08:07 AM   #256
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QuoteOriginally posted by dlacouture Quote
In the end, the problem is more that with high-iso prowess, the K5 made us try shots that we never would have considered, even with the K7...
.
Sorry, I have to disagree with this. The problems I see are at exactly the same shooting conditions that my K100D Super never had a problem with. The FF issue is present in my studio shooting wit the modeling light from my two AB400s. My K100D Super did not suffer from this problem. I wish the issue was that I was trying to push the camera too far.

01-24-2011, 08:14 AM   #257
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I'm too lazy to read every post in detail, so apologies if the following has already been suggested:

Since the AF Fine Adjustment is saved in any given User Mode, it may be useful for some to create a user mode with settings appropriate for those situations where one encounters AF problems, and use that mode in those situations.

Another thought: IF we are convinced that some K-5s DO NOT have this low light focusing problem, it may be useful to investigate the possibility that there may be some inter-dependencies in the settings that may explain why the problem occurs only for some users. It is a (theoretical) possibility that setting A affects how function B behaves, so that users who have/have not engaged some particular setting may have results different from those who did the opposite. Unfortunately, this would be difficult to test, given the huge number of possible permutations of the various settings, but perhaps someone who has the problem is able to try using all default settings, and start from there if AF works. or conversely, try to reset one setting at a time and see if problem disappears.
01-24-2011, 08:29 AM   #258
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QuoteOriginally posted by bxf Quote
I'm too lazy to read every post in detail, so apologies if the following has already been suggested:

Since the AF Fine Adjustment is saved in any given User Mode, it may be useful for some to create a user mode with settings appropriate for those situations where one encounters AF problems, and use that mode in those situations.
Wouldn't work since the amount of FF depends on the light AND focal length. The 18-55 kitzoom is ok between 35-55mm but way out at 18mm (more than can be compensated for). A single value can not compensate for such a behavior.
01-24-2011, 08:37 AM   #259
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Simple. Use the DA or FA limiteds...

QuoteOriginally posted by Gimbal Quote
Wouldn't work since the amount of FF depends on the light AND focal length. The 18-55 kitzoom is ok between 35-55mm but way out at 18mm (more than can be compensated for). A single value can not compensate for such a behavior.


01-24-2011, 08:41 AM   #260
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QuoteOriginally posted by Gimbal Quote
Wouldn't work since the amount of FF depends on the light AND focal length. The 18-55 kitzoom is ok between 35-55mm but way out at 18mm (more than can be compensated for). A single value can not compensate for such a behavior.
Fair enough, but now we're in the unsolvable problem area that exists quite apart from the low light problem. i.e., some zooms require different AF adjustments at different focal lengths. I have lenses that (on the K20D) need negative adjustment at some FL, and positive adjustment at another FL. Sadly, there is no acceptable solution for this.
01-24-2011, 08:50 AM   #261
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QuoteOriginally posted by bxf Quote
Fair enough, but now we're in the unsolvable problem area that exists quite apart from the low light problem. i.e., some zooms require different AF adjustments at different focal lengths. I have lenses that (on the K20D) need negative adjustment at some FL, and positive adjustment at another FL. Sadly, there is no acceptable solution for this.
Yes, but then the same kitzoom works ok through the entire range as long as the light stays above EV4. Below that something suddenly happens, and it's almost like flipping a switch, go below the threshold and the focus ring stops at another distance.
01-24-2011, 10:46 AM   #262
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QuoteOriginally posted by bxf Quote
Since the AF Fine Adjustment is saved in any given User Mode, it may be useful for some to create a user mode with settings appropriate for those situations where one encounters AF problems, and use that mode in those situations.
Well, the lenses' AF Fine Adjustment values are not saved individually in USER mode. These values are general, and shared by all modes (I already tried this solution).
The only thing saved in USER mode is whether AF adjust is enabled or not.
01-24-2011, 10:49 AM   #263
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QuoteOriginally posted by dlacouture Quote
Well, the lenses' AF Fine Adjustment values are not saved individually in USER mode. These values are general, and shared by all modes (I already tried this solution).
The only thing saved in USER mode is whether AF adjust is enabled or not.
You are absolutely correct. I explored this option myself and ran into a dead end.

01-24-2011, 12:31 PM   #264
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QuoteOriginally posted by bjan Quote
Did you have direct contact with any Pentax People regarding the issue concerned ?
Yes ......
01-24-2011, 01:03 PM   #265
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QuoteOriginally posted by falconeye Quote
Moreover, without a more controlled test it really isn't possible to draw any conclusions.
Yes, I agree. My only conclusion is that in real life images I've yet to see the issue with this K-5, so I'm a happy camper

QuoteOriginally posted by falconeye Quote
Nevertheless, if I find a practical way to do a controlled test delivering numbers which can be compared, I'll ask you to participate
I'm alone on this and next week, so I'll probably have some time for a quick controlled test. Until then, I just made two "quick and dirty" shots, first one with a 20W tungsten desk lamp's light bounced off the wall (LV according to exif 2.6), second one only lit by a small candle (LV according to exif -0.3). First one seems to be spot on to me, second one is front focused a bit, but at that low light I don't expect perfect AF (in fact AF hunted a lot and couldn't lock focus for a few tries). Target was 96cm away for sensor plane (32x focal length), lens is Sigma 30 f/1.4, here is the setup, exif full intact in the two shots. This is probably a flawed test, but then my real life shooting is flawed in the same way

As someone mentioned, some settings might also influence whether the issue happens or not? I know that the settings on this K-5 are not exactly the same as on my previous K-5 (which exhibited the issue under the same conditions).

Anyways, let's wait what Pentax comes up with. We can speculate, do (flawed, uncontrolled) test and argue as much as we can, it probably doesn't/won't have much influence on Pentax's answer to this interesting issue
01-24-2011, 01:35 PM   #266
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QuoteOriginally posted by falconeye Quote
Originally posted by bjan Did you have direct contact with any Pentax People regarding the issue concerned ? Yes ...... __________________ Falk
Maybe I have missed something but can you tell me what PENTAX is going to do about the issue ? Are they neglegting the whole thing because they cannot do better wich is a possibility or are they really working on a solution and if so on what term can we expect that ?
If you don`t have answers from Pentax on these questions from wich I am sure you will have asked them maybe you can tell us about the information you got out of your direct contact with PENTAX in respect of this issue . Thanks very much if you would share that with us.
01-24-2011, 03:20 PM   #267
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QuoteOriginally posted by dlacouture Quote
Well, the lenses' AF Fine Adjustment values are not saved individually in USER mode. These values are general, and shared by all modes (I already tried this solution).
The only thing saved in USER mode is whether AF adjust is enabled or not.
Oh really? Sorry, I guess I didn't take my "experiment" far enough. When I saw that the AF Adjustment ON/OFF setting was mode dependent, I surmised that the actual settings would be carried along to the individual modes. My apologies.
01-24-2011, 06:17 PM   #268
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I'd like to see the AF adjustment settings for each lens allow a range of adjustments for each focal range of a zoom.

Modern lenses report the focal length to the camera so there's no reason why this can't be featured.
01-24-2011, 06:17 PM   #269
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QuoteOriginally posted by simico Quote
here is the setup, exif full intact in the two shots.
Your setup doesn't look too flawed. The biggest drawback is the possible inclusion of out of focus detail in the area which may still be covered by the center AF sensor. The center AF region is large (unfortunately). Somebody or myself have still to make an AF sensor region overlay for the K-5.

QuoteOriginally posted by bjan Quote
can you tell me what PENTAX is going to do about the issue ? Are they neglegting the whole thing because they cannot do better wich is a possibility or are they really working on a solution and if so on what term can we expect that ?
I can share this much: Pentax Europe (US probably as well, I just have no info) is highly aware of the issue and considers the problem to impact their sales. It is or was discussed with Tokyo at a management level. But Pentax Europe cannot tell me anything about the current state of things or if or when it will be fixed. From other sources I learned that Pentax Japan is indeed working on this. But these sources didn't reveal the nature of the problem either.

I know from my K-7 shutter blur study that I can outperform the analytic capabilities (or time allowances) of the Pentax development lab in Tokyo. E.g., they didn't know if they solved the problem for the K-5 before I redid my test and told them ... Therefore, I wouldn't exclude the possibility that providing an exact test procedure and evidence if all or not all K-5 are affected could help them fix the issue. This is why I'll try to include simico's K-5 should I decide to look into this in more detail. For a start, I already purchased 15W and 25W tungsten bulbs. And 40W bulbs in 5 different colors which is possible despite them being banned in the EU now.

Last edited by falconeye; 01-24-2011 at 06:25 PM.
01-24-2011, 08:25 PM   #270
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I have the same low light issue with my new K-5. It seems to be affected DA Limited lens ( I have DA 21mm , and new DA 18-135), but absolutely no issue with my FA 35mm f/2.0 with the same test setup. A focusing in LV with all lenses is spot on every time. It is very strange and frustrating. Hopefully, Pentax listens and will fix it.

Mike
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