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11-07-2009, 06:57 PM   #16
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QuoteOriginally posted by BB_Zone28 Quote
Just wondering, does anyone know how (or where) Pentax derives their values for Color Temperature (CT) that differs from so many other sources?

Many cameras and published literature refer to Daylight CT as being around 5500 K and then all the other CT values hinge around that value.
However, the Pentax K20D manual claims Daylight CT about 5200 K.
I know that 300K is not a huge amount of difference, but isn't science still SCIENCE regardless of the camera maker. Or are scientific definitions now up for grabs like everything else in this relativistic "post modern" brain wash that everything else pretends to now be in a dumbed-down politically-correct cultural world where you can imagine that anything is true if it's true for you? : (after all, many folks believe it's absolutely true that there's no absolute truth!!!!)

Just speculation, but does the chosen CT daylight value include some offset corrections for the specific Bayer filter used on it's sensors or the specific color processing algorithms and PRIME processor? If so, why not apply corrections internally and used the same CT numbers as most other literature uses???
Nikon d70 used 5200 as well......
#396878 - ufraw: Uses incorrect temperature values for Nikon D70s white balance presets - Debian Bug report logs
"daylight" setting is variable, that's why you have the more accurate Kevin scale......

11-08-2009, 11:03 AM   #17
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QuoteOriginally posted by Marc Sabatella Quote
Nor would I. But here, we're talking about basic exposure controls that cannot be altered once the shot is taken. WB is just number that can be used in converting the data to JPEG, but I don't see any reason to expect standardization there any more than I see a need for standardization on exactly how much sharpening or noise reduction should be added.

Because the named settings themselves aren't standardized, much less their values. Sure, the names tend to be pretty similar, but then, so are the values. And in any case, they're just JPEG processing settings; they aren't really important enough to standardize. If you really care about WB, you shoot RAW and set the WB there where you can be as specific about it as you like. Most JPEG shooters would have no reason to care about consistency here, any more than care that the "sepia" processing available in some camer's JPEG engines might work differently. Camera makes like to differentiate themselves on image appearance. It's just not a big deal to most people, so there is no incentive to standardize on details like this.

So I'm not saying it would be *bad* to standardize, just that 99% of the world doesn't care, so camera companies spend their time on other matters.
I think you've given a reasonable assessment of some of the issues from the perspective of a knowledgeable, advanced user. I would mention that we do modify exposure settings in the sense that we can lighten/darken the image in post processing as preferred. (but that doesn't change f/# dof or shutter's motion blur effects)

Color appearance can be a very subjective thing from photographer to photographer just like sharpening. It's nice we have the ability to adjust it to preference via software.

Still it would be nice to have the named CT values more standardized for consistency. You mention 99% don't care, but I've noticed among photography students just beginning to learn digital, they almost all seem to care. ...there's confused expressions on students faces when they realize their camera doesn't use the same values as another student's camera and their first question is "WHY?". They are already intimidated by the whole Kelvin CT and White Balance thing and then see that camera makers can't even agree on what's called what... it just seems to jump out at them as another obstacle to gaining confidence as they're learning to use digital cameras. (especially those individuals who are not very technically oriented in the first place)...
Who knows, maybe at some point a voluntary standard may be proposed and the learning frustration level across the whole world will be slightly reduced!

Last edited by BB_Zone28; 11-10-2009 at 11:26 AM. Reason: grammar/content
11-08-2009, 11:15 AM   #18
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QuoteOriginally posted by creampuff Quote
BB_Zone28, first off not all cameras are the same in terms of size, weight and color. The K-7 and K-x has proven that.

But the issue is not about Pentax not sticking to a so called common standard. It is merely a decision the engineers would have opted for. At any rate this is something that you can change yourself to your preference. You're making a mountain out of a molehill imo.



For your info, manufacturers do vary a lot in adhering to so called known standards. Some DSLR cameras makers have often "cheated" on the stated ISO. ISO 100 would be actually ISO 125. Even in film days, there were plenty of films that were different from their rated ISO/ASA/DIN rating.
Thanks for showing the chart. I'm going to set my own custom K values to use instead of the named presets.

Last edited by BB_Zone28; 11-10-2009 at 11:24 AM.
11-08-2009, 11:18 AM   #19
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QuoteOriginally posted by KungPOW Quote
Maybe you should join an ISO standards group?
Or maybe a Kelvin WB standards group? I appreciate your suggestion. It funny that you should mention that since I used t work in a Standard Lab for optics and electro-optical equipment calibrations.

As somebody said, if they at least give the Kelvin CT value for their preset WB "named" values you at least know what you're working with!!!!!

A nice thing about the K20D is that you can assign up to three custom "preset" values based on Kelvin if you don't prefer the "named preset" choices provided by the camera maker.


Last edited by BB_Zone28; 11-10-2009 at 11:37 AM. Reason: revise
11-10-2009, 12:06 PM   #20
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Not wanting to "beat" a well discussed topic into the ground, but I had one other idea about the Kelvin Color Temperature (CT) values for the White Balance (WB) "button presets" chosen/used in digital cameras that can vary from one camera maker to the next.

Most camera makers are good about listing the Kelvin CT values for their WB "button preset" assignments for most camera models IN THE CAMERA MANUAL ONLY, but what's displayed on the camera's LCD screens is just a small ICON that represents one of the several different WB presets the user can select.
I think it would make things clearer if they would list the Kelvin CT value IN THE CAMERA next to each WB preset ICON so you know what choice they made for their assignment of CT to that ICON. That would compensate for the somewhat arbitrary choice different camera makers use for their WB button/ICON preset assignments so you know what your are really selecting in terms of Kelvin CT. Sure I could try to memorize all those values listed in manual, but then the next camera I buy will have different values assigned and "here we go again" trying not to mix up which camera is which...basically I'm saying "why not make this feature more user friendly???"

Better yet, make the WB preset/ICON values all editable so you can assign the values that you prefer. Then you can match them up with your digital workflow so you're image editing software "named presets" can match your camera, etc. Especially nice if you have a flash you use regularly with a known specific Kelvin CT output distribution of light.
11-10-2009, 01:05 PM   #21
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Back to the orig topic ;)

QuoteOriginally posted by BB_Zone28 Quote
Just wondering why (or how) Pentax chooses the values for their Camera's Color Temperature (CT) that differs from so many other sources?

Many cameras and published literature refer to Daylight CT value as being around 5500 K and then all the other CT values hinge around that value.
However, the Pentax K20D manual claims Daylight CT about 5200 K.
First I showed this statement is most likely not true...

I would like to know what camera(s) do this....
It seems that for some cameras the WB settings are not preset values but some recommendation to the camera's auto WB. To test this you can take two pictures with the same WB setting, but very different lighting condition. If you get the same channel multipliers it means that theses values are valid preset values, that can be used in UFRaw. If they differ, you can send me the information, but I'm still not sure how it will be handled.

QuoteOriginally posted by BB_Zone28 Quote
I know that 300K is not a huge amount of difference, but isn't science still SCIENCE regardless of the camera maker. Or are scientific definitions now up for grabs like everything else in this relativistic "post modern" brain wash that everything else pretends to now be in a dumbed-down politically-correct cultural world where you can imagine that anything is true if it's true for you? : (after all, many folks believe it's absolutely true that there's no absolute truth!!!!)

Just speculation, but does the chosen CT daylight value include some offset corrections for the specific Bayer filter used on it's sensors or the specific color processing algorithms and PRIME processor? If so, why not apply corrections internally and used the same CT numbers as most other literature uses???
One thing to remember is "color temp" is defined by the white balance color multipliers.
RGB. And if you look at this chart it will show you that probably all the cameras differ in this area.
UFRaw - Contribute
The Bayer array filters probably contribute a small variation due to difference in absorption...
And if your out in the field shooting and you pick 5330K and the sun goes through a wispy cloud the real color temp changes... If you want all cameras to pick the same color temp, use a custom wb and force all multipliers to 1:1:1......
I'm not sure what you really want (a camera "standard" when nothing is possible to standardize here?)
BTW: Beginners will not worry about 5500 vs 5200 if the shot is "pretty".....
Besides that's what RAWS for, the multipliers have not been perminently applied to the data so you can harmlessly color it to any temp you want....
I understand being frustrated w/ camera to camera differences but that's why pros (in almost any field) stick w/ one "brand" or learn a couple at best. Worring about Sony vs Pentax vs Olympus vs Leica seems an exercise in frustration.....

Last edited by jeffkrol; 11-10-2009 at 02:53 PM.
11-10-2009, 01:35 PM   #22
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I consider the standards to be the White Card and 18% Grey Card. If precision is needed they work much better than any pre-set button.
11-10-2009, 09:10 PM   #23
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Anyway, for the newer Pentax cameras like the K-7 and K-X, the Colour Temperature quoted for each WB setting is just a default starting point. The WB will do its own auto adjustment around the selected WB setting, depending on how the scene lighting changes.
It still allows you to fix the set WB (no auto adjustment), if that's how you prefer it.

Personally, I've never had an issue with Daylight WB , used in daylight.
In fact, I've found Daylight WB a bit warm and I prefer to use AWB most of the time.
Its all a matter of taste, which the Pentax camera allows you full control over.

11-11-2009, 10:28 AM   #24
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QuoteOriginally posted by jeffkrol Quote
First I showed this statement is most likely not true...

I would like to know what camera(s) do this....
It seems that for some cameras the WB settings are not preset values but some recommendation to the camera's auto WB. To test this you can take two pictures with the same WB setting, but very different lighting condition. If you get the same channel multipliers it means that theses values are valid preset values, that can be used in UFRaw. If they differ, you can send me the information, but I'm still not sure how it will be handled.
So, you're saying that you've found some camera's selectable WB presets (icons) are not actually set to a fixed CT, but a suggested starting point for the Auto WB to adjust the final WB calculations.

I visited your link, it looks like your Raw editor adjusts it WB presets to match each specific camera model's same "preset" values for WB as claimed by the camera maker. That's a nice feature!!!
11-11-2009, 10:32 AM   #25
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QuoteOriginally posted by DavidWasch Quote
I consider the standards to be the White Card and 18% Grey Card. If precision is needed they work much better than any pre-set button.
You said it! Custom WB is usually best. Just have to watch out where the light is coming from when you take an exposure to set the WB if you have mixed light sources with different CT values.
11-11-2009, 10:37 AM   #26
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QuoteOriginally posted by kittykat46 Quote
Anyway, for the newer Pentax cameras like the K-7 and K-X, the Colour Temperature quoted for each WB setting is just a default starting point. The WB will do its own auto adjustment around the selected WB setting, depending on how the scene lighting changes.
It still allows you to fix the set WB (no auto adjustment), if that's how you prefer it.

Personally, I've never had an issue with Daylight WB , used in daylight.
In fact, I've found Daylight WB a bit warm and I prefer to use AWB most of the time.
Its all a matter of taste, which the Pentax camera allows you full control over.
So it sounds like I've been making a BIG ASSUMPTION that what the camera manual means when it lists different "named" WB icons being assigned a Color Temperature (CT).
Do you have any references published by Pentax that claims these are actually starting points instead of a fixed, assigned value????
11-11-2009, 10:58 AM   #27
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QuoteOriginally posted by jeffkrol Quote
...
I'm not sure what you really want (a camera "standard" when nothing is possible to standardize here?)
BTW: Beginners will not worry about 5500 vs 5200 if the shot is "pretty".....
Besides that's what RAWS for, the multipliers have not been perminently applied to the data so you can harmlessly color it to any temp you want....
I understand being frustrated w/ camera to camera differences but that's why pros (in almost any field) stick w/ one "brand" or learn a couple at best. Worring about Sony vs Pentax vs Olympus vs Leica seems an exercise in frustration.....
My question was poorly stated on the first post on the first page, but as we've discussed this topic I hope I've been able to more clearly and specifically articulate what I was asking....

I've just noticed the inconsistencies between camera makers on the CT values they assign to their "named" icons that you can choose from to set the camera's WB. One camera uses a "Daylight" preset of 5500k, another assigns it to be 5200k. Then I've noticed that all the other "preset" WB icon selections are shifted by about the same amount as their daylight differences. I understand that CT varies during the time of day and if there are clouds, etc. What I was asking is why would it be so difficult for camera makers to agree on a "standardized" set of CT values to be assigned to each named "preset" icon for the sake of consistency from one camera to another. After all, they choose the same f/#, ISO and shutter speed values (for the most part) from one camera to another.

I agree that beginners don't care as long as the picture looks "pretty". But those who begin to learn to use more than "automatic" settings get confused in the classroom when they see that camera makers differ on what CT values they assign to their WB "preset icon" settings.
But they don't get confused about shutter speeds because they are fairly consistent between cameras. SO, WHY can't the WB preset values be consistent also and reduce the confusion? That's all I'm asking. I know that technically you can use whatever values they give you for CT and WB, but you could do the same with any arbitrary shutter speed number also. So, why should camera makers even agree on the numbers for shutter speeds if it doesn't matter? (just like most claim WB preset values don't matter) I think is because it's a nice consistency to have between cameras in order to make using cameras more user friendly and easier to pick up different cameras and AT LEAST HAVE A FEW THINGS THAT ARE COMMON between them.
Thanks for you response to my comments!!!!
11-11-2009, 11:20 AM   #28
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QuoteOriginally posted by BB_Zone28 Quote
Do you have any references published by Pentax that claims these are actually starting points instead of a fixed, assigned value????
According to the manual, either is possible at the user's option. The K-7 can either used fixed presets, or use the presets as a starting point for automatic fine-tuning.

Page 192 of the English-language manual:
The camera automatically performs fine-tuning even when the light source is specified. The color temperature of the light source is fixed when [11. WB Adjustable Range] in the [Custom Setting 2] menu (p.85) is set to fixed.
Page 85 of the English-language manual:
11. WB Adjustable Range: Sets whether to automatically fine-tune the white balance when specifying the light source on the white balance setting.
According to page 288, the default setting is "Auto Adjustment", ie. the camera fine-tunes preset white balance.
11-11-2009, 12:12 PM   #29
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QuoteOriginally posted by knoxploration Quote
According to the manual, either is possible at the user's option. The K-7 can either used fixed presets, or use the presets as a starting point for automatic fine-tuning.

Page 192 of the English-language manual:
The camera automatically performs fine-tuning even when the light source is specified. The color temperature of the light source is fixed when [11. WB Adjustable Range] in the [Custom Setting 2] menu (p.85) is set to fixed.
Page 85 of the English-language manual:
11. WB Adjustable Range: Sets whether to automatically fine-tune the white balance when specifying the light source on the white balance setting.
According to page 288, the default setting is "Auto Adjustment", ie. the camera fine-tunes preset white balance.
Thanks knoxploration. I just looked in my K20D manual and page 161 has similar comments on the fine tuning (starting point) vs. fixed. Amazing, I've read through theses sections and read right past that...maybe because it was in the gray box "footnotes" looking section so must have just ignored parts of it??
It's also nice that Pentax enables you able to assign your own "custom" Kelvin CT values, if desired. Flexibility is a good thing!

I guess if you use "fine tuning" feature, then any named "preset value" could be argued to be irrelevant to the final image results. However, the fixed setting "preset values" would still make sense to have some consistency as I discussed in previous postings above.
11-11-2009, 01:26 PM   #30
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QuoteOriginally posted by BB_Zone28 Quote
I've just noticed the inconsistencies between camera makers on the CT values they assign to their "named" icons that you can choose from to set the camera's WB. One camera uses a "Daylight" preset of 5500k, another assigns it to be 5200k. Then I've noticed that all the other "preset" WB icon selections are shifted by about the same amount as their daylight differences. I understand that CT varies during the time of day and if there are clouds, etc. What I was asking is why would it be so difficult for camera makers to agree on a "standardized" set of CT values to be assigned to each named "preset" icon for the sake of consistency from one camera to another. After all, they choose the same f/#, ISO and shutter speed values (for the most part) from one camera to another.
Because they want a different look, predominantly for skin tones would be my guess..
5200 being "warmer" then 5500K.
I seem to remember something about the temp is more flattering to Asian skintones..
or was it European? Camera makers DON'T even standardize iso, nor f stops either. They pretend to.
Lenses are not even exactly as stated in f stop nor focal length...
The old lens tests used to state the REAL focal length and real f/stop based on measurements of their own.
exposure meters can be the worst and don't even go into the tone curves (which are always different in each camera.

It's all smoke and mirrors anyways....
http://doug.kerr.home.att.net/pumpkin/Color_Temperature.pdf
Understanding White Balance

QuoteOriginally posted by BB_Zone28 Quote

I agree that beginners don't care as long as the picture looks "pretty". But those who begin to learn to use more than "automatic" settings get confused in the classroom when they see that camera makers differ on what CT values they assign to their WB "preset icon" settings.
I assume they will get just as confused if they had the exact same K temp yet each photo w/ different cameras looked "different" which would probably happen..
QuoteOriginally posted by BB_Zone28 Quote
But they don't get confused about shutter speeds because they are fairly consistent between cameras. SO, WHY can't the WB preset values be consistent also and reduce the confusion? That's all I'm asking. I know that technically you can use whatever values they give you for CT and WB, but you could do the same with any arbitrary shutter speed number also. So, why should camera makers even agree on the numbers for shutter speeds if it doesn't matter? (just like most claim WB preset values don't matter) I think is because it's a nice consistency to have between cameras in order to make using cameras more user friendly and easier to pick up different cameras and AT LEAST HAVE A FEW THINGS THAT ARE COMMON between them.
Thanks for you response to my comments!!!!
As stated earlier daylight is defined between 5000-6500K, none would be incorrect and to pick 1 that all camera makers use would be like getting them to be all the same RAW format... and my favorite quote which can be universally applied across the board..
I think teaching them to learn their camera is more important then the K scale...
'The exposure meter is calibrated to some clearly defined standards and the user needs to adjust his working method and his subject matter to these values. It does not help to suppose all kinds of assumptions that do not exist.'
Erwin Puts
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