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02-05-2010, 02:07 AM   #1
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Weird K-7 White Balance Anomaly

Okay, haven't seen this one addressed anywhere. I've done a few shoots where flash was the only light source. My K-7 is set to flash white balance, flashes are set manually (optical, not ttl slaved) and exposure is set manually (1/180s to kill the ambient). Shooting conditions are stable (indoors, lights on stands, etc.). And yet the colour 'walks' all over the place. Some shots are warm some are cool, all shot in RAW (DNG).

In Pentax Digital Camera Utility 4, they're all recognised as being set to 'Flash'. In Lightroom 2.6 however, the Kelvin rating is all over the place (4600K to 6150K), and if I manually put in the same number (eg 5000K), the whole sequence of images come into range and they look as expected.

Can anyone explain what's going on here? The amount of post this is causing is totally ridiculous -- having to touch each image is tedious! I've used this camera for about 4 important shoots with flashes, and have had this issue each time.

02-05-2010, 02:48 AM   #2
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Custom function #12

Hi and welcome,
Your problem might be related to Custom function #12: WB Adjustment range - when on Auto it does additional adjustment even if fixed preset is selected.
Also take a look at CF #11 settings in Your camera.
Best and happy shooting, JR
02-05-2010, 07:27 AM   #3
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QuoteOriginally posted by elemeno Quote
Okay, haven't seen this one addressed anywhere. I've done a few shoots where flash was the only light source. My K-7 is set to flash white balance, flashes are set manually (optical, not ttl slaved) and exposure is set manually (1/180s to kill the ambient). Shooting conditions are stable (indoors, lights on stands, etc.). And yet the colour 'walks' all over the place. Some shots are warm some are cool, all shot in RAW (DNG).

In Pentax Digital Camera Utility 4, they're all recognised as being set to 'Flash'. In Lightroom 2.6 however, the Kelvin rating is all over the place (4600K to 6150K), and if I manually put in the same number (eg 5000K), the whole sequence of images come into range and they look as expected.

Can anyone explain what's going on here? The amount of post this is causing is totally ridiculous -- having to touch each image is tedious! I've used this camera for about 4 important shoots with flashes, and have had this issue each time.
One nice thing about Lightroom is that you can apply a single setting to a full set of images instead of opening and modding one at a time. You can set as many as you like, including just one (ie, White Balance). The same thing is possible if using Adobe Bridge. I know with my current CS4 setup, I can open up to 25 PEF files at one time, apply settings to all of them, and generate the JPGs. It's actually quite quick (on my Windows 7 laptop). I can do basically the same thing with LR. Not calling you out specifically but many people think LR is just a cataloging program and don't take learning the software much beyond the very basics.
02-05-2010, 09:46 AM   #4
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Thanks for the responses!

This gives me a couple of options to try out.

Jeff, I didn't feel called out by your comment -- I just downloaded and tried Lightroom for the first time yesterday. :-)
While that's certainly a useful tool, it doesn't explain why my camera is generating this problem in the first place. Set on daylight WB while shooting outdoors during the day, I'm not seeing this issue. My concern is that for a wedding of several hundred images I'm still going to have to go through determining which are available light, which are flash, and which are mixed. No tool is going to turn that into a snap...

Hang on sec -- I may have found it! Custom function 10 puts the camera in AWB when the flash is going. What? That's crazy talk! I wish I had my camera with me right now to fix it right this second. I searched white balance in the manual's index before posting, but it didn't direct me to the custom functions that control it. D'oh!

Thanks for pushing me in that direction, Reps.


Last edited by elemeno; 02-05-2010 at 09:47 AM. Reason: fixing the layout
02-05-2010, 11:41 AM   #5
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I realize I didn't answer your question directly, just proposed a solution to the dragged out process of fixing the photos. Having been somewhat disappointed by the Pentax WB Indoors (especially AWB) since my first camera (K10d, 2006), I've grown accustomed to not trusting it completely. Or rather not trusting how the camera reads lighting conditions even shot to shot in the exact same situation. It has become better with each model upgrade but still fails sometimes. I don't really blame Pentax for this, there is no way in hell they can predict every situation we'll put these cameras in. Only best guess at what most of them will be. It's for this reason that I never stray from shooting RAW+.

You had said your camera was set for Flash WB, or so I thought, so the setting isn't something I drove towards in my response. For the most part, the custom menu setting to change to Flash WB when using Flash, has cured most of my WB problems but even that isn't always consistent. I've read all kinds of excuses as to why the Pentax WB sometimes fails to be correct and chose not to add another one.

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