Get ready to have your mind blown - maybe. You might have heard me complain bitterly in the past on various issues surrounding white balance but today I am actually going to focus in on some specifics along with a few illustrations and actual numbers. Typically I refrain from the numbers or even passing judgement on any notion correctness as I firmly believe concept is and internalization is a much more important point than any particular specifics. The specifics change as time goes on, tastes vary but concept and developing your eye doesn't really change that much unless what you want to achieve does.
Even if you don't use Aperture 3 - say you use Lightroom or even something else a lot of this conversation is applicable but the numbers will be different so read on. Everything you thought you knew might just be thrown a little off kilter here… or not but you may be amused anyway.
The genesis of this somewhat long-ish post was actually a far longer conversation on white balance, color correction, and other post processing topics I have with someone that was using some of the Portra film emulation presets for Aperture 3 and actually started off innocently enough but as usual any conversation related to color rendition must, must, must start and sometimes end with white balance. I have said it a million times before and will say it again. The biggest influence on color rendition is not your camera, RAW processor, or some preset you use (unless it's a nutty surreal effect) - it's the white balance that you or your camera choose.
The first conceptual hurdle in the wonderful land of digital post processing and RAW processors to overcome is that white balance temperature and tint numbers are completely arbitrary between different cameras and different RAW processors. Assuming they are some set standard is a really bad idea - they should be. They were in the film days - yea they could be a little off for various reasons but 5600K was 5600K. In my opinion until some how the various purveyors of RAW processing software come up with a way to translate the number you see and manipulate into whatever number it needs internally they shouldn't even give users the impression that it's "K" as in degrees Kelvin temperature of a black body. They may as well just use an arbitrary scale of numbers from 0-1000 or whatever.
Assume the above is true - you can't go wrong if you do. If you just happen to have a camera like a Hasselblad H4D and use Lightroom the temperature and tint numbers in white balance might just match up with what you would expect and what everyone discusses when having white balance conversations. However there's a good chance they don't. In fact there is a good chance they are not even close. The answer is to test and know the general ballpark ranges for various lighting conditions.
For this conversation I'm going to use my Nikon D600 for the actual numbers. My Fuji's are different values but are absolutely not even close to the "standards". So just to start off let's take a look at what the numbers look like for built in camera preset white balance settings once inside Aperture 3…
- Tungsten = 3200K/1
- Daylight = 6251K/8
- Cloudy = 7509K/6
- Shade = 10,618K/19
- A setting of 5600K = 6806K/5
Let's not even get into florescent settings, that's another can of worms… Take a look a those numbers for a second. Hmmm tungsten seems pretty close, okay daylight, WTF? all the rest are in the holy-shit-ski realm. There's a couple of things to take from this - the first is that you probably should know the general realms of what's what, especially in the shade neighborhood as you can't even make the slider go up that high in Aperture 3 without some special maneuvers or typing a number in. If you happen to be using Lightroom the numbers are completely different and also are nowhere near what other conversations of white balance and color temperature would have you believe.
Are these numbers the differences in manufacturer flavors I've discussed in how different cameras render color before? No, those exist as well but they are nits compared to this. Those are a few percent different in temperature and tint not miles apart like 10,000+ being the number that's supposed to be somewhere in the neighborhood of 7500K-ish for camera shade preset white balance.
Do yourself a favor know what the general realms of your camera preset WB numbers are in your RAW processor so that when your auto white balance is off the mark you at least have some sort of notion on where to start. A good place is usually somewhere in the ballpark of the shooting conditions and the numbers that correspond to those WB preset settings unless you happen to have a measurement using a gray card/white balance target which is always a good idea but not always the ultimate answer. The tweaks from that point are a matter of taste and what sort of feel you happen to be going for.
It's also important for Aperture 3 users as there are many conditions where the simple white balance tools don't work well. For example the skin tone mode. Works great in a lot of circumstances - others not so much. Where does it fall down? From my observations it falls down if the actual numbers go outside some arbitrary range of temperature values. Values like over 10,000 or anywhere close. Too bad even the very very conservative "shade" preset for the D600 happens to be closer to 11,000K. Real world open sky is far higher than that in "real numbers" let alone Nikon/Aperture 3 numbers which seem to be even higher. This creates a situation where a very common and attractive lighting scenario also is a situation where most camera auto-WB falls down (real numbers larger than 8000-9000K) and Aperture 3's sampling tool for skin tone also will not work in those ranges. What to do if you happen not to have used a target? Well you could start with the numbers Aperture 3 uses for Nikon D600 or your camera's shade if you happen to know what they are.
So now it's time to discuss white balance targets and measurements. I am not so religious when it comes to using white balance targets. If I were doing commercial work I would sure as hell have a lot of different reference points for location work. In fact I would probably end up spending an hour or four prior to actually shooting figuring out various color management strategies for any particular environment or location I was going to use. Here's a few examples of why I would do that…
Let's take a really simple example of the conditions I was shooting granddaughter #1 in two days ago. Simple enough, sunny day on a shady porch…
Now that's simple enough right? Let's just use the shade numbers right? We'll let's take a look at the spot where I was snapping away with a white balance target.
Okay that's 9950K/19. Not too far off from the Nikon shade setting in Aperture 3. Ummmm wait just a second what about the other direction.
Hmmm that's 6473K/21? Well if that's different that's two completely different color temperatures in the same exact spot and they happen to be about the same exposure so that's going to be a fairly substantial issue if actually shoot where the subject is split and lit with both. let's take a look at what's going on about 7 or 8 feet down the porch.
What? 14,000K/21. Three completely different color temperatures in the same general location. Yep. Is this somehow way strange? No. In the real world of ambient light this is pretty typical and it's why "auto" is not the answer and white balance targets are not a one shot deal and done. If you are shooting "serious" work with some sort of spec that has to do with color and you are using a location you are going to have to manage this and have a plan - and some gear. Bringing strobes to the table - yet another thing to manage. Just to reenforce this notion how about moving one floor up to the balcony above also a porch, same side of house…
Hmmm, talk about wildly different 23,398K/16. This is a circumstance where just about all cameras auto WB fails as well as way outside of the range that Aperture 3's skin tone tool will function and make an effective adjustment. It's handy to know what the range of numbers are inside your chosen RAW processor for common shooting conditions.
Mostly just some food for thought and to help some of you out that are struggling with color correction and reading all sorts of "numbers" on the internet that all seem to leave out the huge detail of the fact those numbers are meaningless inside most third party RAW processors with most cameras. Especially in common conditions where auto WB falls down pretty badly. At the end of this all trust your eyes. If you shoot scenics just about any color will do. If you shoot people ummmm not so much. Yes there is a lot of room for taste variations but that's about 10 or 20 percent on the side of cooler/warmer and pinker greener. Pretty much the difference between various camera auto WB and preset flavors. You definitely need to be in the right ballpark for most cases with people and then adjust to taste warmer/cooler pinker/greener and usually this will be a few percent not wild fluctuations unless going for "effect".
Personally when I bother to fine-tune color for people I tend to go a few percent warmer with sunlight or just as often dead neutral. In softer/shadier/cloudier conditions I tend to go a few percent cooler as it feels a bit more natural for me as the scene felt. In most cases I also go a teeny tiny bit pinker. Changes with my mood.