Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-09-2011, 09:47 AM   #1
Site Supporter
bxf's Avatar

Join Date: Jul 2010
Location: Lisbon area
Posts: 1,121
More about low light AF

Much has been said about the K5 low light AF difficulties, but it's not necessarily easy to form a conclusion from all the mixed comments.

I've been going gaga trying to perform AF fine adjustment for each of my lenses, but I simply cannot achieve any consistency. Where some test may show a -5 setting to be optimal for a particular lens, another test may show something different, sometimes very different.

It has occurred to me that the problem may be due to different types of lighting that I may be running my tests under. For example, real tungsten in one test and energy saving lights in another. In fact, this raises the thought that perhaps this is the reason some people have the problem and some do not i.e. shooting under different lights.

Do we have any definitive conclusions about the extent to which different lighting conditions affect the K5 FF problem?

Thanks for any input.

04-09-2011, 11:08 AM   #2
Pentaxian




Join Date: Mar 2009
Location: Perth Australia
Photos: Albums
Posts: 1,511
Where has the thread with the fairly conclusive and exhaustive testing gone....
04-09-2011, 12:43 PM   #3
Senior Member




Join Date: Nov 2009
Location: Marin, CA
Photos: Gallery | Albums
Posts: 281
How about forgetting about trying to find fault with your camera, and just go take some pictures?
04-09-2011, 01:00 PM   #4
Site Supporter
Bramela's Avatar

Join Date: Jan 2007
Location: Newcastle Australia
Photos: Gallery | Albums
Posts: 5,281
Yes, I agree. My k5 can't be that different. I have tried it in darkish room, dark street scene, etc etc, and have yet to have any noticeable problem with lowlight AF, and that is with a number of different lens.
There has been far too much rumour spreading about, and makes people think there has to be something wrong.

Even improved after the last firmware update.

04-09-2011, 02:46 PM   #5
bxf
Site Supporter
bxf's Avatar

Join Date: Jul 2010
Location: Lisbon area
Posts: 1,121
Original Poster
I wish it were so simple

QuoteOriginally posted by qtopplings Quote
How about forgetting about trying to find fault with your camera, and just go take some pictures?
Unfortunately, the faults found me. I've already previously posted a couple of shots with horrendous focus:

https://www.pentaxforums.com/forums/pentax-k-5-forum/133556-what-%25%24-*-no-1-a.html

I have many more such examples, taken with various lenses. Af adjustment and/or FW 1.03 has helped a lot, but neither perfectly nor consistently.
04-09-2011, 02:53 PM   #6
bxf
Site Supporter
bxf's Avatar

Join Date: Jul 2010
Location: Lisbon area
Posts: 1,121
Original Poster
QuoteOriginally posted by Bramela Quote
Yes, I agree. My k5 can't be that different. I have tried it in darkish room, dark street scene, etc etc, and have yet to have any noticeable problem with lowlight AF, and that is with a number of different lens.
There has been far too much rumour spreading about, and makes people think there has to be something wrong.

Even improved after the last firmware update.
As I point out in my reply to the previous post, I'm not trying to validate a rumour.

It appears that I simply get different focusing shifts under different lighting, and this is not necessarily related to very low EV. To make things worse, even under any given conditions I have inconsistency, where one or two shots are sharp and the rest definitely off.
04-09-2011, 02:59 PM   #7
Veteran Member




Join Date: Apr 2010
Location: Suomi , Finland
Posts: 373
Kun itse aloitin valokuvauksen yli 50 vuotta sitten, ei ollut viellä tietoa AF. Olen ottanut kymmenillä kameroilla hämärässä, melkein pimeässä ja aina on onnistunut ilman ruikutuksia. K-5 on jo montakertaa parenpi kun minun ensimmäiset kamerani.
04-09-2011, 03:05 PM   #8
Junior Member




Join Date: Feb 2011
Location: Styria
Posts: 30
What about the Firmware-Update 1.03... did it fixed the issue?

04-09-2011, 03:05 PM   #9
Pentaxian




Join Date: Mar 2009
Location: Perth Australia
Photos: Albums
Posts: 1,511
I've certainly seen the front focus issue on 1.02, but not since the firmware update 1.03 (in real world conditions) however some testing has shown its still there. (though i believe testing showed it was reduced)
04-09-2011, 03:20 PM   #10
bxf
Site Supporter
bxf's Avatar

Join Date: Jul 2010
Location: Lisbon area
Posts: 1,121
Original Poster
QuoteOriginally posted by 30v iPentax Quote
Kun itse aloitin valokuvauksen yli 50 vuotta sitten, ei ollut viellä tietoa AF. Olen ottanut kymmenillä kameroilla hämärässä, melkein pimeässä ja aina on onnistunut ilman ruikutuksia. K-5 on jo montakertaa parenpi kun minun ensimmäiset kamerani.
I have poor and inconsistent focus in EV6. The focus shifts are not necessarily worse under lower light levels.
04-09-2011, 03:26 PM   #11
bxf
Site Supporter
bxf's Avatar

Join Date: Jul 2010
Location: Lisbon area
Posts: 1,121
Original Poster
QuoteOriginally posted by pentmax Quote
What about the Firmware-Update 1.03... did it fixed the issue?
QuoteOriginally posted by WerTicus Quote
I've certainly seen the front focus issue on 1.02, but not since the firmware update 1.03 (in real world conditions) however some testing has shown its still there. (though i believe testing showed it was reduced)
FW1.03 improved things, and AF adjustment even more so. But the inconsistency is there. And just to emphasize, I'm not talking about particularly low light levels - LV 6 (according to PhotoMe, though this leads to another question: PhotoMe is saying LV 6, while showing the individual matrix segments as being in the range of LV3.5-4.5. strange).
04-09-2011, 03:37 PM   #12
Junior Member




Join Date: Feb 2011
Location: Styria
Posts: 30
Testchart

For those with af problems i have a really good test chart...


Beacuse of the fact that the issue occurs also on reddish objects, a red testchart reveals af issues...


so maybe some of you can post their results here using the added charts...

RED CHART

WHITE CHART


For quick tests you can use your screen! For me it worked the same way as the printed version... but maybe it depends on the type of your computer screen....
04-09-2011, 03:41 PM   #13
Pentaxian
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 10,157
I think something we are just going to have to live with regarding the K5 is some AF inconsistency in low light/ some colours of light. It looks like they managed to get something not quite right in the AF, and this is being magnified tremendously by the low light performance of the imaging sensor allowing people to work in light levels that were unphotographable previously.

I would debate that EV6 would be a problem, and would wonder exactly what the original file looks like. The performance of the sensor is such that an underexposure of several stops can be salvaged in post, and this can make the EV level look a lot higher than it actually is.
It is not really possible to accurately measure EV with a reflected light meter, one needs an incident meter that is colour calibrated to do it properly.
04-09-2011, 03:42 PM   #14
Veteran Member
jolepp's Avatar

Join Date: Oct 2010
Location: Finland
Photos: Albums
Posts: 3,196
As for definitive conclusions: no. My impression is that some still suffer from low (tungsten) light AF problems which FW 1.03 mitigated; otoh some reported no problems even before the update. An explanation for this would be that the problem occurs with some copies of lenses with some copies of bodies as is the case with FF/BF in general. My guess for a root cause would be chromatic aberrations produced by the combination of the lens optics and those in the AF sensor. Pentax lenses could be better matched than 3rd party ones in this respect, that is, with them there is a fair change that such matching has been a design consideration.
04-09-2011, 06:53 PM   #15
Veteran Member
Smeggypants's Avatar

Join Date: Sep 2010
Posts: 1,536
My first K-5 ahd severe FF problems in low light. V1.03 did NOT fix it.

I got the camera replaced. The replacemetn camera exhibited the same FF problems in low light but V1.03 DID fix it. Two days after that I bought a 2nd K-5 and it's low Light FF problems were fixed with 1.03.

The original K-5 was built in December 2010, the replacement and second K-5 were built in Jan 2011 and Feb 2011 respectively.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
af, camera, dslr, k-5, k-5 ii, k-5 iis, k5, light, lights, pentax k-5, test
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
very low light k-5 lowlight Pentax K-5 19 04-10-2011 12:42 AM
Low Light? How about Zodiacal Light? KansasHorizons.com Pentax K-5 31 03-03-2011 03:23 PM
People Low light with DA* 16-50 barbosas Post Your Photos! 2 11-24-2010 08:10 AM
Low light versus Poor light d.bradley Pentax DSLR Discussion 4 07-11-2007 07:53 AM
Low Light - Low Experience - Fix $$$ ? daacon Pentax SLR Lens Discussion 35 04-26-2007 07:52 PM



All times are GMT -7. The time now is 07:43 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top