I deliberately exposed the 'pack shot' of the Expodisc under the worst possible lighting - office strip lights. The nearest the camera's own white balance could do was as pictured. The image to its left is the corrected version.
The main shot is using the same Expodisc white balance, with the exposure adjusted. This shows how precise the Expodisc really is.
In terms of getting the correct white balance, they work very differently, but the end result is the same. I believe that the WhiBal is the thing to go for if you are planning post-capture white balancing; the Expodisc corrects at the scene itself.
As I said in the review, the Expodisc works by you walking up to the subject matter with your camera and pointing the Expodisc-covered lens back at the point you are taking the picture from, and taking a Custom White Balance reading from there. That's the joy and the downside of an incident light reading - it is not influenced by colour of the subject matter itself, but sometimes getting to the subject matter is impossible.
The WhiBal requires you to be in the same light as the subject matter. You then take a shot of the WhiBal, photograph as normal and then use the WhiBal shot as a reference point for post-processing.
The shortcomings of both are obvious. If I am sitting in a Land Rover staring at lions in safari, it's going to be pretty damn difficult walking over to them to get an accurate white balance at the subject matter's viewpoint, which makes the Expodisc a tough call to recommend in such situations. On the other hand, if my subject is indoors under tungsten light and I am outside in daylight, the WhiBal reference shot won't work, either. All of which means, if you are going to be really, really consistent, you need both solutions.
In fairness, I don't have a sample of the WhiBal... yet. That's a review for another time. Instead, I use a Lastolite thingy - not as accurate, but it performs the same function as the WhiBal.
Jonathan once pointed out some lens cleaning cloths which could be used for white Balance. I have lost the thread and can't remember exactly how it worked, but it seemed a good idea at the time.???
Essentially, in theory, if you have any known and consistent thing that can be put in the same light source, you can take a white balance off it. Although, if your 'known and consistent thing' is a rose-pink hanky, it makes life a lot harder.
Even with a grey or white cloth, the problems occur with achieving the words 'known' and 'consistent' though. A sheet of paper may look 'white' to our 'easy to fox' eyes, but realistically it will likely have a slight colour cast that will influence your images if you use it to white balance against. A cleaning cloth is similar in that it looks grey, but might not be quite as grey as we think. That said, if it comes down to that or nothing in situations where taking a custom white balance becomes vital, then go for it. This is, as American's so elegantly put it, 'good enough for government work'.
The consistent bit comes in because a cleaning cloth is not necessarily colour-fast and its colour balance may subtly shift under sunlight or from the ingress of the dust you have fastidiously cleaned from your lenses. This is less of a problem than the original colour of the cleaning cloth in the first place, but is something to consider nonetheless.
Products like the Expodisc and WhiBal are supplied with their RGB numbers written on a data chart supplied with the product, so that you can be broadly sure of what you are starting with. If you want to be really, really thorough about your colour balance, you could include a photograph of the blank Expodisc image and use those RGB settings in photoshop to create possibly the most accurate WB around. As long as you remember to put your Expodisc and WhiBal back in the box afterward and not let the sun get to it for too long!
Well, the problem is a 18% grey card and a white balance card do different things, and they behave differently too. A WhiBal, for example, isn't that good for exposure, because it's nowhere near 18% grey for exposure. A Kodak Grey Card (especially an older grey card) is great for exposure, but not so hot for white balancing because its reflectivity can return some distinctly odd results.
Here's a useful Lightroom trick for determining the accuracy of your grey card. Take a photo of said card (raw or jpeg) and drag it into LR (or any other program that shows a colour histogram). Now look at its histogram. A card that's good for exposure might have a red, green and blue peak, all centred around the 18% grey point. A card designed for WB will have these red, green and blue spikes on top of one another, but not necessarily on the 18% grey point.
I'm not sure whether the Spudz thingy deals with accurate exposure or accurate white balance. My worry is that, if you put it through the wash too much, you end up losing accuracy on both.
I suppose it depends how fussy you are. I've used an old T shirt for metering before now. If I can get to within 1/3 stop then I'm usually pretty happy.
Yep thanks Jonathan, I was racking my brain trying to think of where I saw it last. I remember now it was one of the nice prices on the Advent calendar.
Alan, I understand what you are saying, but I don't think I am good enough to be that concerned about that level of accuracy. I remember my friend having the Expo Disc and singing its praises for a couple of weeks and then never using it again afterwards. I think if I get a cleaning rag at least it is going to be used.
), how does this compare to something like that?
I remember my friend having the Expo Disc and singing its praises for a couple of weeks and then never using it again afterwards. I think if I get a cleaning rag at least it is going to be used.
