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Is Color Temperature Irrelevant?

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  #1  
Old 11-26-2007, 01:28 PM
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Doug Nelson Doug Nelson is offline
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Is Color Temperature Irrelevant?

I'm working on a small still life lighting setup and had to consider which lights to use. I first considered daylight flourecents, then figured I'd save some money and go with "regular" tubes and fix it in Photoshop. Of course, then I thought that, since I was going to "fix it" later anyway, why not save 100% and just use some tungsten lamps I have laying around?

This, in turn, got me wondering if color temp even mattered anymore (as long as it's not mixed, of course). Is it just a timesaver, avoiding color correction work later, or does it actually affect how/what colors you can capture?

I'll grant that broad spectrum lighting is a good thing, since monochromatic lighting such as sodium vapor would essentially be shooting in black and white. But just restricting the conversation to temperature, does it matter?
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Old 11-26-2007, 02:02 PM
Michel B Michel B is offline
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Re: Is Color Temperature Irrelevant?

I am curious what others have to say about this. Part of the answers lies in your statement that full spectrum is needed. Any fluorescent light lacks parts of the spectrum and it does matter. About tungsten, studio photography with tungsten and special films is not inferior to daylight or studio strobes with daylight films. If you mean that by shooting raw, you can correct afterwards, I think that color temperature is not a quality factor. I think others will give tips about calibrating your raw conversion. There are specific color or grayscale charts to be photographed under your lighting to find the right temperature and tint in the raw conversion.
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Old 11-26-2007, 06:36 PM
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Re: Is Color Temperature Irrelevant?

As Michel notes, IF the light is full-spectrum, colortemp isn't important other than matching it in-camera, either with the appropriate film (tungsten or daylight) or digital white balance. If it's shot on film with the wrong balance or in JPEG with the wrong balance, you will lose a lot of your color capture, but other than those mistakes, it's independent.
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Old 11-26-2007, 07:13 PM
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Re: Is Color Temperature Irrelevant?

I must agree with Michael B, the color temp isn't that important if you use a gray card or a color card 'cause with these kind of cards you can balance the image on PS, but if the color balance of the final image is too far from the original scene you can lose detail on shadows and highlights. I prefer to use the gray card with the proper lighting always.

Silvia.
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Old 11-26-2007, 08:37 PM
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Re: Is Color Temperature Irrelevant?

I've personally found that getting the white balance right in camera seems slightly more "true" to the original colors than post processing/white bal/color cast correction seems to be. However, I bet it would be close shooting raw with a gray card and good post process. This is probably testable, in that you can set up a still shot, camera on tripod with cable release, shoot with known lighting and match in camera, then change the lighting and reshoot with a gray card. Open the second image, post process as accurately as you can, then sample the two images in the same exact spot and compare RGB values (with the hypothesis of the first image being "right" and seeing how close to it you come with post process).

It's a little like exposure to me, getting it right in camera is just a little better than fixing it in post, but the options for fixing either later nearly eliminate the need to get it "perfect" at capture for most applications.
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Old 11-26-2007, 11:56 PM
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Re: Is Color Temperature Irrelevant?

Doug,

You surprised me by asking a question like this but here is my 2 cents worth..

I agree with Mucker about getting it right in camera.. I have spent way to much time in the darkroom fixing things that could have been avoided with a proper shoot utilizing the seven "P"s.

To answer the question "Is Color Temperature Irrelevant?"

NO! It is not irrelevant if you want the right colors..

We are not working much with dyes any more so we do not have to match the emulsion to the color temperature to get daylight colors. With Digital Photography and especially with RGB we may want to change our vocabulary to "White Balance"

A majority of digital cameras require measurement and adjustment of the color temperature to ensure that a white object is recorded as white, and to guarantee that other colors are also close to their acceptable limits. Usually adjusting to around 5,000 to 5,500 Kelvin or daylight..
This process is often referred to as adjusting the White Balance, and is a software and/or hardware option on many digital cameras. The computer chip inside the individual camera is usually set up for that particular camera and the charts used are likely to be more correct than anything you could do in Photoshop..

If you shoot without adjusting the White Balance (color temperature) and your shots come out a muddy red or greenish blue and you try to color correct in Photoshop or other software, then your colors are going to be guessed at for the second time (first in camera.. then when you eyeball them) and may be hard to get right.. this is one incident where getting it right the first time (with a white card) will pay out rewards down line.. less noise, less work, and less guessing later in the process towards getting a good print (image), unless you wanted that muddy red or greenish blue.

In digital Photography it seems that using a white card for White Balance is the better choice because the RGB system is one of the primary color models utilized to specify and represent colors. White is produced by combining equal parts of all three colors (red, green, and blue) at levels of 100 percent. In color digital cameras adjustments for color temperature can easily be made by adjusting the intensity level of one or more of these primary colors in order to produce acceptable color images that conform to the color temperature of the illumination source.. the processing circuitry provides a series of look-up tables, which are utilized by the software to adjust the red, green, and blue signals in order to arrive at the proper color balance for a specific illumination intensity and color temperature. Often, the look-up tables will contain information about a variety of color temperatures from a lot of common illumination sources.

Sooo, Does it matter?

YES!!

Use whatever light source (Color Temperature) you have available that will do the job... Just make sure you adjust the White Balance, if you want it adjusted for daylight, to conform to the Color Temperature before your first shot!

OR

If your White Balance is left at daylight or 5,000k or turned off, then whatever light source you selected would be captured IE., orange for tungsten or greenish for florescent or the color for which ever color temperature your light source emitted.

And this sort of answers your other question.. "Is it just a timesaver, avoiding color correction work later, or does it actually affect how/what colors you can capture?".. Yes, it does affect what colors you capture. It all depends what you do in camera first, as far as your White Balance.

It also depends what you want for a final outcome..



Disclaimer..
These are just my rambling thoughts and may well be way off.. but it works for me..
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  #7  
Old 11-27-2007, 01:48 AM
Michel B Michel B is offline
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Re: Is Color Temperature Irrelevant?

Certainly true for jpegs... However, as far as I know, WB camera settings don't affect the sensor chip at all, it only tells the built-in processor how to convert raw data to jpeg, and tag the resulting raw file with the WB setting you chose, which would represent your shooting intent. Let's take the example of Canon software. Zoombrowser includes the same software than the camera and can produce afterwards any of the in-camera settings from the raw files. I used once this feature to simulate a common shooting error: leaving tungsten setting in daylight. I could compare the difference in the R,G,B curves and find the correct curves settings to correct in batch a set of bad exposures.
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Old 11-27-2007, 02:25 AM
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Re: Is Color Temperature Irrelevant?

why not buy good lights once for all and dont have to worry about it ?
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Old 11-27-2007, 02:47 AM
Michel B Michel B is offline
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Re: Is Color Temperature Irrelevant?

Quote:
Originally Posted by Hello_taipan View Post
why not buy good lights once for all and dont have to worry about it ?
Sure, that's pro advice! But it never hurts to try to understand...
By the way, I really like your style and your site.
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Old 11-27-2007, 07:36 AM
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Re: Is Color Temperature Irrelevant?

thanks for ur kind words michel, it's nice to see parisian ppl around here. im from paris also.(half of the time)
cheers
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