Feedback on K-5 low light tungsten focussing issue in real life / portrait photos ?

Started May 5, 2011 | Discussions
alexh3o New Member • Posts: 11
Feedback on K-5 low light tungsten focussing issue in real life / portrait photos ?

Hey everyone,

I feel like upgrading from K200D but one of my favorite kind of photography is low light portraits, indoors or outdoors with city lights, therefore almost always with tungsten light.

I fear that low light tungsten front/back focusing issue that’s been raised on K-5, but there’s all kinds of answers on whether firmware 1.03 fixes it or not, and falklumo stands it’s not : falklumo.blogspot.com/2011/03/lumolabs-pentax-k-5-low-lig....

Finally I have no idea whether that would be a real life issue or not and I could not find clear information on any forum !

Could users give feedback (or even better post photos) on taking portraits with shallow depth of field by low tungsten light only ?

If there’s an issue, does it make a difference setting the WB to tungsten manually ?

I’m posting a pic to illustrate the kind of picture I’m talking about.

Thanks

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awaldram
awaldram Forum Pro • Posts: 13,271
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

Whilst I don't have any tungsten light sources I did a number of shots to find out just what the hiatus was about.

The long and short of it is if the light source is in the image then the k5 will focus under all light colours, I've lost the 1.02 image for the obscured image where ff was visible under PD.

The first image is Phase detect under conditions where it is alleged focus will be accurate under all colour temperatures.(light source in shot)

This is a crop of the phase detect above

This is the same set up under the same conditions but under live view taken to show that Phase detect would continue to deliver accurate results in light levels where LV has failed.

And this is a 1.03 shot with the set-up configured in a known way to induce FF under low tungsten/candle light.

I leave you to draw your own conclusions.

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audiobomber
audiobomber Veteran Member • Posts: 5,766
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

I bought a K-5 which was clearly having trouble with AF in tungsten light. Focus worked fine in daylight, so I loaded v1.03 and did some testing. Unfortunately the new firmware didn't help. I know some people have a K-5 that works in tungsten light, but I decided to give up for now and returned the camera.

Here's my test, using the K20D with FA 35mm at f2 and a DA 40mm on the K-5 and K-x. Handheld, because I wanted a real life test, which includes shake reduction and auto exposure. I set Av to f/2 for the K20D, f/2.8 for the others, auto ISO, noise reduction turned off.

https://picasaweb.google.com/bonhommed/LowLightTest?authkey=Gv1sRgCKfrw5i3lJihcQ#

For those who can't be bothered to look, tungsten AF on both older cameras outperformed the K-5 by a margin that doesn't require pixel peeping to spot.
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OP alexh3o New Member • Posts: 11
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

@awaldram, thanks for your feedback

Last shot looks good, but i read from pentaxeros forums that it only happens in certain shades of tungsten, so maybe candle lighting, though close to tungsten temperature and color, is a bit different and not concerned by the issue.

It's good to see that in some similar photographic cases it seems to work very fine though.

@audiobomber

Thanks for examples, which, though handheld, are worrying and quite clear I think...

There still are lots of tungsten bulbs here in france, and big iso and low light focussing capabilities just happen to be missing with my k200d mostly in that special case :-/ It's hunting so much with the fa 50mm f/1.4, and i'd make good use of higher shutter speeds...

I'll wait for more feedback to get some stats out of it, and hope for some feedback with wb set manually on tungsten...

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Philnw2 Veteran Member • Posts: 3,683
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

I'll feel your pain There must be thousands of posts by now on the K5 Tungsten light issue, and i've have read a lot of them, including posts on the Nikon D7000 site for their similar issue.

All cameras, of course, are affected by tungsten light. The real issue here is whether the K5 with firmware 1.03 has focusing capabilities sufficient to meet our standards.

I do a lot of volunteer work at a live play theatre organization. We do portraits for the actors and photos of the dress rehearsals etc. They are very strict about no flash usage for any stage work. And they also will not accomodate photography by altering their light program for any play. So thats the background.

So I knew for a long time that i needed a better iso camera than my K20, i found it limiting for candid shots around the theatre and also for some plays, like Chekov's Seagull play. I was about to bite on the Kx, and then the K5 came onto the scene. I waited for this whole thing to settle out and finally bought a K5 in Feb 2011. I'm currently the lead photographer, but often call in friends to help with the workload. Two of these friends have upgraded to the Nikon D7000, because we all became acutely aware of the difficulties faced by our older generation camera sensors.

For the current play, i sorted through 1000 photos from my K5 and about 400 from a D7000 shooter. The D7000 shooter has yet to "learn" her camera, when she shot at 25,000 iso, i found the shots generally too noisy to use in the lobby, but then she switched to 10,000 iso during the play and those shots were much better. She doesn't as yet know how to auto-float the iso for her camera. I usually shot with TAV at a top sensitivity of 12,800 iso.

For the lobby display of 30 photos from the play, about 75% of mine and the rest hers. With my K20, i would often use 3200 iso and sometimes up to 4500 but the IQ due to noise was limited at higher than 3200 iso.

Conclusion: I'm getting more compliments over the latest photo display than anything i put together before. Personally, I would not consider going back to the K20, although i'm keeping it as a backup camera. When i'm not shooting for the theatre, I also like low light stuff, shooting street lamp lit sidewalks, dark alleys, and bridges when its so inky black, one can't see the water below. IQ and percent of keepers went up when i shifted to the K5. I think i got one of the newer K5's, no stain and focus performance has been fine. I do put in a -5 focus adjustment on my Tamy 28-75 f2.8 that i often use in the theatre, but i used that same adjustment with the K20.

By the way, I read one post/thread on Pentax Forums where someone claimed that he got less front focus by using the tungsten setting rather than the auto WB. I plan on trying that. I actually find it easier to process photos that are all done under the same manual setting, for synchronizing toning adjustments for the same scenes.

By the way2, I found that processing the photos to be a similar experience between those taken with the K5 and the D7000. Up to 12,800, Lightroom3 NR does a commendable shot cleaning them up.

If you are just going to do static shooting with a tripod, then one can forget the upgrade. But if you are doing lowlight subject movement pictures, then i think the upgrade is worth trying. The quiet shutter on the K5 is really nice, the D7000 is almost as quiet. The auto horizon sounded to me like superficial nonsense, but then i found myself doing a lot less straightening of photos. When you are developing photos in time for opening night performance the next day, it can make a difference.

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K5, K20D,

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martweb Contributing Member • Posts: 821
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

With my K-5 and FW 1.03 I have no issue under tungsten light.

awaldram
awaldram Forum Pro • Posts: 13,271
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

Hi Dan,

I wonder if there’s two issues with the k5 under low light as there seems to be two levels of error.

Those with very marginal FF under extreme low light like myself (with 3 bodies) which 1.03 completely fixes.

And those like yourself and smeggypants (other forum and PenatxUK forum) who had bodies that showed extreme ff under any kind of redish WB, for who 1.03 seems to not only not help but make it marginally worse.

I think the second case requires a new body as it seems to be a hardware fault, I know smeggypants was getting very frustrated until he returned the camera for a replacement.
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audiobomber
audiobomber Veteran Member • Posts: 5,766
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

awaldram wrote:

I wonder if there’s two issues with the k5 under low light as there seems to be two levels of error.

I had a similar thought when I went to download v1.03. The description didn't seem to match my problem:

Improved the accuracy of auto focus in low-intensity light condition.

I was seeing accurate focus in low ambient daylight and fluorescent light, severe front focus in tungsten. Clearly it was the colour of the light that was a problem, not the intensity. I thought Pentax had solved that issue with the K-7, but the K-5 I tried was a step backwards from my older cameras.

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OP alexh3o New Member • Posts: 11
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

@Philnw2

Thanks for that informative answer. I've also considered switching brands to the D7000 because of less reported issues (i think), lens availability and investments long-term viability with nikon, but i'd miss that level correction, the body's build quality (which i find a little less on the nikon) and compact size, shake reduction for primes, which you can't get at nikon for 50mm f1.4 as an example.

One of the main motivation for upgrade are like these dim tungsten light outside terrasse headshots with the fa 50mm, where the k200d hunts focus a lot and misses like 2 extra iso stops...

I guess your K-5 copy's quite fine, or at least not having negative impact on your low light photography, which is encouraging.

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(unknown member) Veteran Member • Posts: 3,992
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

Purchased two K-5's in the past two months and both are spot on under tungsten lighting.

OP alexh3o New Member • Posts: 11
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

Hi johnbee,

Are you using screw-driven lenses, and around which exposure settings or EV values have you been shooting at ? Could you give the first figures or your serial number (like #402xxx) ?

I forgot to mention that interesting information from pentaxeros, found elsewhere

"...

I run a shop in Spain only in Pentax (Pentaxeros.com Store), And all who come and sell cameras are tested by me one by one and updated the firmware, etc.

And all units tested, including the last with serial number: 39XXXX, all under the same controlled light situation I have, and that play, act like all K-5.

Why many do not detect them is due to several points:

  • Only with bright lenses, focusing screw. (Not everyone has limited or light lenses)

  • It is only with certain shades of tungsten.

  • It only happens in very low light situations, and the threshold at which the light does not turn for help. If you turn the focus assist light, the approach is necessary.

  • Also in the diaphragm is closed from f/5.6, the depth of field absorbs the front focus, being negligible.

The situations in which there is very low.

As I said, do a study report to Pentax, with all the information, and direct labor Pentax Spain and Europe, who are working on it, and that the solution will come by a firmware update.
..."/

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OP alexh3o New Member • Posts: 11
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

Just found the post from smeggypants on pentax user uk forum, which gives the conclusion for him, like awaldram said, he had 1 hardware faulty K-5 and 2 others were fixed by firmware :

I've used THREE K-5s now and ALL OF THEM suffered the low light FF problem. That's no coincidence.
[...]

My first K-5 wasn't fixed by the FW 1.03 update and was one of the duds. I got it replaced ( quickly thanks to SRS's excellent service ) The two K-5s I own now have had the low light front focus fixed by the update.

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xmeda
xmeda Senior Member • Posts: 1,457
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

I was worried before buying K-5. My camera is 1.5 weeks "old" now.

No. 4042302, tested... and it looks OK with no problem. Bought with 1.03 already installed.

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audiobomber
audiobomber Veteran Member • Posts: 5,766
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

xmeda wrote:

I was worried before buying K-5. My camera is 1.5 weeks "old" now.

No. 4042302, tested... and it looks OK with no problem. Bought with 1.03 already installed.

I wish I had looked at the serial number of my bum K-5.

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guy_incognito Regular Member • Posts: 209
Re: Feedback on K-5 low light tungsten focussing issue in real life / portrait photos

K20D and other cameras have had problems with focusing under tungsten light. What has changed on Internet forums is that people have realized that it's the cameras not the lenses that do the focusing. So people have stopped blaming lenses, I hope...

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