What you need to understand is that almostall light has some type of color overtones.
Only a photolamp isspecifically adjusted toproduce pure white light.
However, eventhese expensivelamps can give aslight color cast ofone temperature oranother.
As a photographer, one of the many tasks youmust accomplish during a photo shoot is tocorrectly evaluate the color temperature ofthe scene.
As you acquire more experience and skill, you willbe able to judge color temperatures moreaccurately.
The reason that the color of light in your photographs looksdifferent than the way you saw it with your naked eyes is that theeye gradually adjusts and compensates for color temperatureautomatically.
Your camera - as awesome a piece of equipmentas it is - can not do this. It simply records the colortemperature it sees.
The white balance adjustments you make incamera apply processing to the data that thesensor records and “corrects” the temperature.
However, this does not happen when you areshooting in “camera raw.”
Let’s review what shooting in camera raw actuallyis...
Your sensor is overlaid with color filters that blockout all but red, green and blue light which is thenrecorded on the photosites of the sensor.
These measurements are not actually recordingcolor but the amount of light in each of the colorchannels.
Then your camera analyzes the data - from dark tolight - and translates it into binary code (zeroes andones) onto the memory card in your camera.
The difference in raw and other formats is that thedata is further processed in the camera beforeoutputting to your memory card and raw data goesstraight to memory without any further processing.
Most digital cameras can shoot in raw, jpeg, or tiffformats. Here is a diagram of what happens to thedata after the sensor captures the data.
All of the extra in camera processing of your imagedata reduces the amount of data available whenretrieved from the memory card.
Remember that every adjustment made to any digital imageinvolves the discarding of certain bits or pixels of information.
In every case, shootingin raw gives you theleast amount ofprocessing to theimage data.
This in turn gives you the most data to work with as youdevelop your images on the computer.
However, there are different views on whether adjusting thewhite balance in camera while taking raw makes any differencein the data on your memory card.
These images are from a 2011 article by Sarah Wilkerson thatpurport to show a difference in the exposure quality when usingdifferent white balance adjustments in camera shooting raw. Allexposure adjustments are the same; only the white balanceadjustment is different. It is hard to see in this slide show, but theimage on the right actually has more visual information in it.
This screenshot from the Nikon website says that white balancedoes not affect the data.
All this conversation really does is reinforce what we already knowabout working with our own camera: we need to experiment andtry out every possible variable to know our camera better thananyone else.
So, I did my own experiment with my Nikon D300 to test theresults with MY camera.
I set my shutter speed to 1/80,ISO to 200,and aperture to f/5.6for all of the followingphotographs taken at the sametime using different whitebalance settings in raw format.