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02-09-2011, 04:43 PM   #481
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QuoteOriginally posted by Christine Tham Quote
Just a thought, as it occurred to me Pentax may be shipping new K-5s with a deliberate slight BF to compensate for FF in low light.
if this is the case, a couple questions arise: is this compensation available to folks here? and is it truly the answer to the focus accuracy issues? this is akin to a shim added to something mechanical to get parts within tolerance. outside of mechanical adjustment on the body, the only other way to distribute such a fix would be thru a firmware update--which is what i and many others are hoping for. just as with the stain issue, it will take some official communication from pentax either stating there is no problem, or there is a problem and a fix will be forthcoming.

-raph

02-09-2011, 04:48 PM   #482
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I was in contact with a large Pentax-authorized repair shop yesterday. I wanted to share their message on the FF and flash/tilt issues:

- Pentax are aware of the FF issue. They are currently working on a solution. Workaround: Live-view. This answer came immediately.
- Pentax are also aware of the external flash tilt/bounce issue and looking for a solution to this also. No workaround offered. This answer came after they spoke with Pentax. (My own workaround is flash EV is turned down -1 in the camera which gives remarkably better results.)
- There's no point in sending in the camera for repair/replace for those issues now
02-09-2011, 04:56 PM   #483
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QuoteOriginally posted by Christine Tham Quote
Just a thought, as it occurred to me Pentax may be shipping new K-5s with a deliberate slight BF to compensate for FF in low light.

That would explain why some people (like me) are reporting no FF issues with their K-5, but others with late serial numbers are still experiencing the issue.
I would hope that this isn't the case. Forcing a BF in one set of conditions in order to mask the FF in another isn't. IMHO, a solution. Suppose that one notices the BF and calibrates their lenses. Now they're right back to the original FF issue.

This is the reason that calibrating the lens for low artificial light isn't an answer. A little brighter natural light and the camera is now back focusing.

BTW, I spoke to Pentax USA customer service again today and, once again described the problem and asked if there were any answers. Pentax USA admits that there have been a few calls, but no official admission of any known defect or fix in the works. He did, however give me an email address to send my samples (K-5 vs K100DS from 1 to 8EV) to the K-5 Product Specialist/Manager in Golden, Colorado. Not sure what it will accomplish, but I'm going to send them.
02-09-2011, 05:10 PM   #484
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QuoteOriginally posted by stefanlindmark Quote
Pentax are aware of the FF issue. They are currently working on a solution. Workaround: Live-view. This answer came immediately.
LV is clunky and not what i like. but it does work well.

QuoteOriginally posted by stefanlindmark Quote
Pentax are also aware of the external flash tilt/bounce issue and looking for a solution to this also. No workaround offered. This answer came after they spoke with Pentax. (My own workaround is flash EV is turned down -1 in the camera which gives remarkably better results.)
i have tried this and while it does give good results, some times i get something that is too dark.....but that can be fixed/saved with a little PP

QuoteOriginally posted by stefanlindmark Quote
There's no point in sending in the camera for repair/replace for those issues now
still holding onto my stained K-5 since i cannot bear to part with it just yet a baptism + wedding are on the horizon for this wknd, and 2 wknds from now. and then it's being sent in........

thank you for sharing stefanlindmark

-raph

02-09-2011, 05:59 PM   #485
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Does anyone else...

Does anyone else have very different results with different lenses? I got more formal in testing my camera today in low light. My FA50 gave me right on results (once I calibrated it for daylight earlier today) in light as low as 1.7 EV. But my DA40 at 2.8 (max aperture) gave me terrible results (strong FF) until about EV 4. BUT my FA 100 macro was right on in light as low as 2 EV. My DA* 50-135 gave right on results until the light got below 3 EV and then only slightly FF in the 2 EV range. And I used a focusing chart, tripod, all the appropriate stuff for the test to make sure I got reliable results.

I was interesting that in the low EF of the 1.7 range live view wouldn't focus lock for my DA 40. Same for the FA 100 macro although the macro regular focus was on.

How can this be lens dependent? Is it something with less than 50mm?
02-09-2011, 06:14 PM   #486
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QuoteOriginally posted by jrforman Quote
Does anyone else have very different results with different lenses? I got more formal in testing my camera today in low light. My FA50 gave me right on results (once I calibrated it for daylight earlier today) in light as low as 1.7 EV. ...
With my first unit, my best lens was my Sigma 70-200 HSM II. With #2 it was the FA77 1:1.9 and with #3 it was the FA50 1:1.4. In all cases certain lenses could be adjusted for a given light level but would drift with changing light levels. There ware also certain lenses that -10 was not enough.

I set up to do a little formal testing on Saturday night, took a few shots at 4EV with both the K-5 and K100DS using my DA55-300 @ 300mm. I got tired and quit. I picked up again on Monday evening and found that the amount of FF @ 4EV was less than it was Saturday night. I shot a series of side-by-side shots form 1 to 8 EV. The whole time I was bothered by the fact that the amount of FF had changed. When I was done I mounted my FA50 and tested it again. For the same AF fine adjust setting it had shifted to BF. I am at a total loss to understand how this could have happened. I should also mention that all of my lenses focus properly when attached to my K100D Super.
02-09-2011, 06:22 PM   #487
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QuoteOriginally posted by Christine Tham Quote
I know I said I wasn't interested in posting in this thread, but I have some new news.
I knew you'd be back


QuoteQuote:
I tried AF fine adjustment calibration of my K-5, and discovered it was slightly back focusing on nearly all lenses. Not enough to actually cause a misfocus when shooting, but clearly the actual focus point is slightly behind where it needs to be.

Perhaps this is the reason why I don't get FF in low light?

Just a thought, as it occurred to me Pentax may be shipping new K-5s with a deliberate slight BF to compensate for FF in low light.
A manufacturer shipping cameras that don't focus properly in regular light levels??


QuoteQuote:
That would explain why some people (like me) are reporting no FF issues with their K-5, but others with late serial numbers are still experiencing the issue.

I may do some tests after my AF adjustment to see if I get any FF in low light. I tried some casual shots yesterday, and still could not get the camera to FF, but these were not rigorous tests.

You mean you joined this thread and claimed your K-5 didn't Front focus in low light and you hadn't even calibrated your lenses?

Unbelievable!!


FWIW the first thing I did when my K-5 arrived was to calbirate my lenses ( in regular light ) and they all required a negative adjustment. IOW they were all front focussing to a degree. I then went out shooting and discovered the FF in low light issue within the hour.
02-09-2011, 07:35 PM   #488
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Okay - I have repeated the test with the same lens (FA 43mm Ltd), but after applying AF fine adjustment.

First photo - showing no FF (ISO 100, f1.9, 0.5 sec, at approx a few inches further from minimum focus distance) - EV 2.8:


Second photo - showing FF (same as above, but 0.8 sec) EV2.2:


As you can see, adjusting for the slight backfocus raises the EV level by which point the camera starts to FF (previously it was around EV1, now it's around EV2.5)

The batteries are spaced about 5mm apart in distance from lens, but the left one is slightly further apart from the centre than the right one (blame it on my butter fingers).

02-09-2011, 07:40 PM   #489
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Forgot to mention, I had a hard time repeating the test, because the AF assist light keep coming on, even at EV3-EV4. Of course, once the AF assist light comes on, the camera is able to focus with no FF.

And once the AF assist light is on, the K-5 will then try and turn it on even if the light levels are slightly increased.

In the end I had to turn the lights fully on to get the camera to stop using the AF assist light.

Interesting behaviour re the AF assist light.
02-09-2011, 08:57 PM   #490
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You could disable the AF assist light in the menu

QuoteOriginally posted by Christine Tham Quote
Forgot to mention, I had a hard time repeating the test, because the AF assist light keep coming on, even at EV3-EV4. Of course, once the AF assist light comes on, the camera is able to focus with no FF.

And once the AF assist light is on, the K-5 will then try and turn it on even if the light levels are slightly increased.

In the end I had to turn the lights fully on to get the camera to stop using the AF assist light.

Interesting behaviour re the AF assist light.
02-10-2011, 12:37 AM   #491
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QuoteOriginally posted by Christine Tham Quote
As you can see, adjusting for the slight backfocus raises the EV level by which point the camera starts to FF (previously it was around EV1, now it's around EV2.5)
So there might be a connection here. My 35 ltd that doesn't need any adjustment doesn't FF nearly as bad as my sigma 17-70 which need -10 and FF like crazy at EV 4.
02-10-2011, 01:48 AM   #492
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QuoteOriginally posted by Eric Seavey Quote
Tommot,
Between the two cameras, did you have any AF fine adjustment differences?

Thanks

no, I did not...both K5 bodies have zero Af adjust with my sigma 17-50 ..and for my eye, K5 number 2 is way better than K5 number one in these low Ev tests...both using the same firmware...seems strange I know..but there you have it !!


EDIT
sorry the highlighted statement is incorrect...

Last edited by Tommot1965; 02-10-2011 at 03:25 AM.
02-10-2011, 02:08 AM   #493
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QuoteOriginally posted by areidjr Quote
I would hope that this isn't the case. Forcing a BF in one set of conditions in order to mask the FF in another isn't. IMHO, a solution. Suppose that one notices the BF and calibrates their lenses. Now they're right back to the original FF issue.

This is the reason that calibrating the lens for low artificial light isn't an answer. A little brighter natural light and the camera is now back focusing.
I've seen a coupla identical posts on the Nikon D7000 dslr forum on dpreview, where a camera had backfocus in normal daylight that shifted to FF in tungsten low light. Its hard for me to conceive that a mfr would ship a camera this way, but some of the similarities of this issue between Nikon and Pentax are certainly interesting.

best wishes,
02-10-2011, 02:55 AM   #494
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sorry I made a mistake..the new K5 is using firmware 1.01

EDiT

some intresting firmware info

the old firmware was 1.01.00.05
this firmware is 1.01.00.08
!!!!!

Last edited by Tommot1965; 02-10-2011 at 03:00 AM.
02-10-2011, 02:58 AM   #495
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QuoteOriginally posted by Tommot1965 Quote
until now that's not been the case
Pffff....
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