Friday, March 20, 2009

Colour Balance & Exposure

Today I am going to ask how you get a correct white balance, and proper exposure. Yes, I know we can all correct the white balance (WB) if we shoot in RAW and select the WB that suits the image.

But what if you need/desire 100% colour accuracy? What if you get a client that is wanting their logo, or a product where colour is key? Or maybe you're just anal like me, and just want the colour to be as spot on as possible. Or what if you only shoot in JPEG, then getting the right White Balance from the start is even more important.
And even in some extreme cases, in an Auto mode, when I was not shooting in full manual, I have noticed a slight shift in the exposure if I had not preset the White Balance before; so while theoretically it should not do that, it has happened. Another reason why I shoot in full manual and preset my White Balance, even when shooting in RAW.

Now there are many tools out there, to help you with needs; all vary in price and size, and that all depends on what your needs are. Lets go over a few of your options:

#1) You may have seen me use my favorite, the ColorBalanceCoach which I have been using for about the last year. The ColorBalanceCoach (C.B.C.) is collapsable disk, much like a average reflector that some of us already own and use, the bottom half is grey, then a black band, and 2 types of white, a solid white and a translucent white. The translucent white is to replicate the average Caucasian skin tone on the histogram.

I use the C.B.C. at the beginning of each sequence of photos that are all in the same lighting scenario, I use the grey section, to set my custom white balance, then I use the section where the solid white, black and grey meet, I photograph that small section and dial in my exposure, the grey should have a peak right in dead centre of the histogram, the white should be the centre of the right section, and the black should be the centre of the left section. If you have one of the peaks to the sides touching the end, you are either over exposed, or under exposed. I then go back to where I will be photographing from, and take one more photo with my subject holding the disk for me, or the disk laying next to the subject. I take the disk out and carry on my shoot.

Anytime I change my lighting, I repeat.

I find this to be a very useful tool, and use mine all the time, but it is not an inexpensive option, at about $110 for the smallest version... but it packs away very small and is in my bag where-ever I go.

#2) The Digital Target, is much the same as I have just described above, but just a different manufacture.

#3) The QPCard, is again much the same idea, but they have some nice pocketable sizes for storing in your camera bag, or jacket/vest; and they have some larger ones that also have known colour swatches for reference (ie: red, blue, green and 24 other colours).

#4) For simple white balance setting, there are products like the ExpoDisc by ExpoImaging, which is available in 2 versions, a neutral, and a portrait. The portrait offers a simple warmer tone to the final image, the neutral is self explanatory. Both are a cap that you pop on the end of your lens, and set your white balance to your lighting by pointing the camera at your light source.

This tool is only good for setting your white balance, and not assisting in the exposure like the ones above. I have used this one before, and I like it, but it is not a cheap option.

#5) The ColorRight is much like the ExpoDisc, and operates the same way.

#6) The Digital Pocket Pack, is something I found on eBay. Much like a smaller version of the Color Balance Coach (C.B.C.), in a 4x6 format and laminated for protection. It looks much like the one at the top of this post, I created that one in PhotoShop.

I will print up and be testing out 2 versions of this card, one where the image is printed on glossy photo paper, and one printed on matte photo paper, then laminated.

I am not 100% sure about the lamination part of this, I would think that the gloss from the lamination will not give it accurate results, but I will test this compared to my C.B.C.; and in the mean time, if anyone wants a copy of the large file of my PhotoShop creation pictured at the top of this post, just ask me and I will email you the full resolution image.

#7) Remember way back when we use to use Grey Cards, well... they still can be used just for this purpose of setting your White Balance, either as a preset (refer to your cameras user manual to find out how to preset on your camera) like I have descibed above, or in post if you have been shooting in RAW.

The Grey Card comes in a 2 pack for about $18 for the pair of them at Kerrisdale Cameras; I would stick one on the bottom of your sock drawer, and one with your gear if this is your method, then every few months, pull the one out of the sock drawer, and compare it with the one in your bag, once it shows signs of obvious fading, toss out the one from your bag, and use the one you had squirled away, go buy a new pack.

If you need assistance in understanding how to read your histogram for any of the techniques I have described above, I suggest that you go here for that, or here.

I hope this helps in some manner for you all.

John R.

PS: Just to remind everyone that the next meeting on, March 23rd, 2009, we will be visited by a guest presenter, the Wedding Guy.


Jon said...

I actually picked up a pack of those Grey Cards from Kerrisdale recently. Works great now that I understand white balance!

Tri-City Photography Club said...

Yes, white balance can be a bit tricky to learn at first, but once you have it down, your can just do it without even thinking about it.

My workflow is so smooth, now that I am using this ColorBalanceCoach; so much time saved from Post Production.