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11-04-2009, 09:04 PM   #1
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Color Temperature in Pentax DSLRs

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.
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???


Last edited by BB_Zone28; 11-10-2009 at 11:29 AM. Reason: grammar/content
11-04-2009, 09:34 PM   #2
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Why should "daylight" have a specific temp?

Is it not just a standard like ISO?
11-04-2009, 10:06 PM   #3
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Color temperature - Wikipedia, the free encyclopedia
11-04-2009, 10:42 PM   #4
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The color temperature of daylight depends on what time of day you measure it, what the humidity is, the season of the year, etc.

11-04-2009, 10:50 PM   #5
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Sorry, there is no single "Scientific" daylight standard colour temperature.

Depending on time of day, seasons, athmospheric conditions, its between 5000 K (evening light) to 5600 K (cloudless mid-day in the Tropics). Most daylight conditions would be somewhere in between

Some other camera makers may use 5500 K (which is fine), but Pentax is not way out if it uses 5200 K as its interpretation of Daylight colour temperature.
11-05-2009, 10:30 AM   #6
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QuoteOriginally posted by KungPOW Quote
Why should "daylight" have a specific temp?
It has to do with "White Balance" and the overall appearance of colors looking cool, neutral or warm in their "color cast".
11-05-2009, 10:47 AM   #7
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QuoteOriginally posted by kittykat46 Quote
Sorry, there is no single "Scientific" daylight standard colour temperature.

Depending on time of day, seasons, atmospheric conditions, its between 5000 K (evening light) to 5600 K (cloudless mid-day in the Tropics). Most daylight conditions would be somewhere in between

Some other camera makers may use 5500 K (which is fine), but Pentax is not way out if it uses 5200 K as its interpretation of Daylight colour temperature.
Most camera brands I've seen use a CT closer to 5500k. Pentax's 5200K choice is on the low end and thereby defaults towards cooler (bluish) color capture during the day unless you're close to sunrise or sunset. What makes it frustrating, is that when you choose "daylight" setting on your camera, then use a RAW file editor like in Photoshop where it's daylight setting is different and thereby changes the color cast from what you just captured. I had an old Canon Digital Rebel years ago and it's RAW files matched up nicely with Photoshop on the CT settings.

Maybe it has to do with Japan having a higher presence of humidity or haze in coastal urban areas where scattering effects come into play and possibly 5200K may yield a better overall looking "white balance"?
11-05-2009, 11:01 AM   #8
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QuoteOriginally posted by BB_Zone28 Quote
It has to do with "White Balance" and the overall appearance of colors looking cool, neutral or warm in their "color cast".
I don't think he was asking what white balance was, but why one would want to define a specific color temperature for something that varies from day to day, place to place, and with meteorological conditions.

11-05-2009, 11:19 AM   #9
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QuoteOriginally posted by knoxploration Quote
I don't think he was asking what white balance was, but why one would want to define a specific color temperature for something that varies from day to day, place to place, and with meteorological conditions.
I wasn't sure if his question was rhetorical. Typing and reading on a BB loses those nuances of expression.

I realize that due to the variable nature of daylight CT, it's fair to say "why limit it to one value?". Unfortunately, for CT/WB there's a button you select on your camera and it has to pick one specific value. I guess my frustration is that there is inconsistency between camera makers and editing software makers on what specific value they ultimately choose for their "daylight" CT/WB setting. Beginners in digital photography have a lot of other things to get used to and deal with besides compounding that with all the inconsistencies between camera makers.

Why can't they agree on a "standard" value for the "daylight" WB button's selection value on cameras and software? Either that or do away with it and just have AWB?
I've noticed that even the Tungsten WB setting differs from brand to brand, but more seem to match studio Tungsten 3200K.
11-05-2009, 12:44 PM   #10
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QuoteOriginally posted by BB_Zone28 Quote
I wasn't sure if his question was rhetorical. Typing and reading on a BB loses those nuances of expression.

I realize that due to the variable nature of daylight CT, it's fair to say "why limit it to one value?". Unfortunately, for CT/WB there's a button you select on your camera and it has to pick one specific value. I guess my frustration is that there is inconsistency between camera makers and editing software makers on what specific value they ultimately choose for their "daylight" CT/WB setting. Beginners in digital photography have a lot of other things to get used to and deal with besides compounding that with all the inconsistencies between camera makers.

Why can't they agree on a "standard" value for the "daylight" WB button's selection value on cameras and software? Either that or do away with it and just have AWB?
I've noticed that even the Tungsten WB setting differs from brand to brand, but more seem to match studio Tungsten 3200K.
Speed, mostly. It's easier to flip between options that are pretty close to reasonable than it is to specifically measure every time. Nothing, of course, stops you from dialing the correct measured value each time. My hunch on the defaults is that it probably stems back to a decision their engineers made about how film reacts. Canon and Nikon both have defaults that over saturate and over warm scenes in my opinion. Suppose that's a matter of taste though.
11-05-2009, 02:01 PM   #11
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QuoteOriginally posted by BB_Zone28 Quote
Why can't they agree on a "standard" value for the "daylight" WB button's selection value on cameras and software?
Why can't all camera makers just agree on the same sensor and everyone use it so all cameras would produce the exact same images? Or all film makers agree on the exact chemical composition of film? Or all lens designers simply use the same optical formulas?

I personally think the lower value for the preset Pentax uses makes more sense, as they are "close" to the correct value for a longer period of time during the day than higher values that are only "close" around noon.
11-06-2009, 05:15 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
Why can't all camera makers just agree on the same sensor and everyone use it so all cameras would produce the exact same images? Or all film makers agree on the exact chemical composition of film? Or all lens designers simply use the same optical formulas?
You forgot to mention to make all cameras the same size, weight and color!
Parts and components aren't the issue, it's more about standards or definitions that are beneficial to camera users to make basic controls and numbers used from one camera to another to have some degree consistency without limiting innovation.

Example: most cameras use ISO values related to 100, like 200, 400, 800 etc. But I guess if a camera maker wants they could use only these ISO values: 73, 146, 292, etc and not even reference values related to 100. WOULD YOU FIND THAT PREFERABLE? I wouldn't!

What about shutter speeds? Why should all camera makers use similar shutter speeds? I think it's because they're numbers familiar to most photographers. The camera maker could choose to use only these values: 1/9, 1/18, 1/36, 1/72, 1/144 etc WOULD YOU FIND THAT PREFERABLE? I wouldn't! They could even call their f/# A, B, C, D etc and skip the numbers and confusion that their values cause for beginning photographers.

So why is it so outrageous, and as I gather from everone's opinions to be "off limits" or "out of bounds", to ask for consistency on degrees Kelvin associated with "named" settings for White Balance?

A large number of hotshoe mountable flash units have a color temperature around 5500k. That makes them quickly setup with colors looking good on most cameras that use Daylight settings closer to 5500k. Those same cameras have a Flash button with a CT slightly higher to add subtle warmth to the colors. They could choose any value they like, but it's convenient to the photographer to not have to fiddle with extra settings to get things to look right.
I use a Metz flash on a K20D that defines the "daylight" CT 5200k and "Flash" CT at 5400k. So out of the box, by default, using the cameras named WB buttons makes the colors fall slightly on the cool side whereas they would be closer to neutral to slightly warm with cameras using "Daylight WB" at 5500k. Same thing happens when using older Sunpak flashes. Skin tones are generally more flattering when on the warm side so I have to fiddle with camera settings to make the colors look right unless I want to post process everything.
So what, why not just adjust them and shut up and quit wasting time on this post?
After all I could get a good exposure using only the ISO and shutter speeds and lettered values for f/# mentioned above if the camera meter is calibrated correctly. So, maybe the WB seems like just a slight thing, but it's overlooked and adds extra fiddling time to set things up. Wouldn't it be better if cameras used standardized values then things would setup and work much smoother with less hassle. Again, shutter speeds and ISO don't have to be the same, but it's really nice to have commonality which I certainly view as better than whatever the camera maker feels like using.

BTW, I looked at the Pentax site on the 540Z and it just says CT is "Daylight".
That seems to imply everyone knows what "Daylight" would be so they don't need to use a CT value to pin it down.
Just more inconsistency??? I ASSUME it's matched to the lower CT presets of K-7, K20D, etc since we don't seem to have any consistency on "daylight" definition!!!!

Last edited by BB_Zone28; 11-06-2009 at 05:39 PM.
11-07-2009, 04:32 PM   #13
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QuoteOriginally posted by BB_Zone28 Quote
Example: most cameras use ISO values related to 100, like 200, 400, 800 etc. But I guess if a camera maker wants they could use only these ISO values: 73, 146, 292, etc and not even reference values related to 100. WOULD YOU FIND THAT PREFERABLE? I wouldn't!
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.

QuoteQuote:
So why is it so outrageous, and as I gather from everone's opinions to be "off limits" or "out of bounds", to ask for consistency on degrees Kelvin associated with "named" settings for White Balance?
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.
11-07-2009, 05:11 PM   #14
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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.
11-07-2009, 06:12 PM   #15
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QuoteOriginally posted by BB_Zone28 Quote
You forgot to mention to make all cameras the same size, weight and color!
Parts and components aren't the issue, it's more about standards or definitions that are beneficial to camera users to make basic controls and numbers used from one camera to another to have some degree consistency without limiting innovation.

Example: most cameras use ISO values related to 100, like 200, 400, 800 etc. But I guess if a camera maker wants they could use only these ISO values: 73, 146, 292, etc and not even reference values related to 100. WOULD YOU FIND THAT PREFERABLE? I wouldn't!

Actually there is variation from camera to camera as to what ISO the camera reports, and the ISO teh camera uses. This, again, is nothing new. Camera brand "A" might use an actual ISO of 95 for their ISO 100, while camera brand "B" uses 90.

What about shutter speeds? Why should all camera makers use similar shutter speeds? I think it's because they're numbers familiar to most photographers. The camera maker could choose to use only these values: 1/9, 1/18, 1/36, 1/72, 1/144 etc WOULD YOU FIND THAT PREFERABLE? I wouldn't! They could even call their f/# A, B, C, D etc and skip the numbers and confusion that their values cause for beginning photographers.

Again, many cameras use a "stepless" shutter speed when the camera is in AV mode. Now I am not 100% sure that modern DSLR's do, but older film cameras certainly did. So it is entirely possable to get a shutter speed of 1/36 in AV mode.

So why is it so outrageous, and as I gather from everone's opinions to be "off limits" or "out of bounds", to ask for consistency on degrees Kelvin associated with "named" settings for White Balance?

A large number of hotshoe mountable flash units have a color temperature around 5500k. That makes them quickly setup with colors looking good on most cameras that use Daylight settings closer to 5500k. Those same cameras have a Flash button with a CT slightly higher to add subtle warmth to the colors. They could choose any value they like, but it's convenient to the photographer to not have to fiddle with extra settings to get things to look right.
I use a Metz flash on a K20D that defines the "daylight" CT 5200k and "Flash" CT at 5400k. So out of the box, by default, using the cameras named WB buttons makes the colors fall slightly on the cool side whereas they would be closer to neutral to slightly warm with cameras using "Daylight WB" at 5500k. Same thing happens when using older Sunpak flashes. Skin tones are generally more flattering when on the warm side so I have to fiddle with camera settings to make the colors look right unless I want to post process everything.
So what, why not just adjust them and shut up and quit wasting time on this post?
After all I could get a good exposure using only the ISO and shutter speeds and lettered values for f/# mentioned above if the camera meter is calibrated correctly. So, maybe the WB seems like just a slight thing, but it's overlooked and adds extra fiddling time to set things up. Wouldn't it be better if cameras used standardized values then things would setup and work much smoother with less hassle. Again, shutter speeds and ISO don't have to be the same, but it's really nice to have commonality which I certainly view as better than whatever the camera maker feels like using.

BTW, I looked at the Pentax site on the 540Z and it just says CT is "Daylight".
That seems to imply everyone knows what "Daylight" would be so they don't need to use a CT value to pin it down.
Just more inconsistency??? I ASSUME it's matched to the lower CT presets of K-7, K20D, etc since we don't seem to have any consistency on "daylight" definition!!!!
Maybe you should join an ISO standards group?
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