Grey Card & White Balancing

DiddyDave said:
'recommend' is a strong word

Is an Expo useful - yep - sure is, and it's easy to use too

Can you live without it - yep - sure can, you just need to decide what's 'white' or even 'grey' and batch process on that basis

If you have the £70 ish burning a whole, then why not (just buy a big one so it'll cover all of your smaller lenses too)

DD
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HAving looked into the expo disc and such like, it wasn't what I thought it was! I thought it was like a lastolite grey card type thing. Spot the newbie amateur!!!

I think for now I'll go with the grey card and batch process in PP, I understand that method.
Thanks for your help DD, much appreciated. Thanks to all who have posted, I didn't realise when starting this thread just how many ways to get a decent white balance there are. No wonder as an amateur/newb I was getting confused.

I do still wonder though if I am making too much of this and thinking a little to technical about this, and making it harder for myself to get a hold on it. :shrug:
 
The thing with a grey card reading, is it is not, and never has been, a magic bullet for all exposure situations. What it does is assumes that the reading you're taking from the card is a mid tone for the scene you're shooting. In lots of scenes we shoot, you can get away with using the grey card reading directly. Any problem areas like white buildings at one extreme, and black objects at the other, are usually of such little consequence to the overall scene that it matters not.

However, as soon as your image is of a black car or a white horse, playing predominant roles in the scene, then you have to make a considered judgement about adjusting that indicated grey card exposure either upwards or downwards.

Similarly in harsh sunlight, with bright highlights and dark shadows, you have to make a conscious decision to bias your exposure towards the highlights at the expense of shadow detail, or vice versa.

All the grey card reading has ever been is a starting point for exposure calculation, although as I said earlier in lots of 'average scenes' we can use the reading directly, and in most cases you'd do better taking a grey card reading and using it directly, rather than just winging it.

All in all, it just makes you realise what fantastic exposure systems cameras have these days, and whilst they can be fooled, they do a damned good job in an awful lot of situations.
 
I read on Flickr somewhere that you can use the lid from a Pringles tub as a substitute expodisc, apparently it does a very similar job!
 
Comfortably Numb said:
I read on Flickr somewhere that you can use the lid from a Pringles tub as a substitute expodisc, apparently it does a very similar job!
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Only with the old clear ones... not the new white ones.
 
Janice said:
Only with the old clear ones... not the new white ones.
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I wonder if they changed it on purpose....I think they may have missed a trick, they could have marketed to togs & turned the tube into a snoot:D

Crisps are a staple for most of us anyway, so two birds with one stone!
 
crt-d said:
my grey card is at 18%
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The 18% grey reference is for calculating exposure. An off-white or very light grey reference source which is manufactured as colour-neutral, such as the WhiBal, is required for colour balancing.

Anthony.
 
AliB said:
The inside of lowepro bags are 18% grey, handy eh? :)
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BTTT for this little gem of info. Never thought of that!
 
Don't forget that when mixing light sources....tungsten inside lighting, possibly mixed with fluorescent too, and then you introduce daylight from your flash........bit of a cocktail there!

In Nikon NX or NX2 you can use a dropper to mark the black, Dmax by clicking it on a proper black item in the scene.
You can then use a white dropper to do the same thing with something that should be 255 white. And for mid tones you can select as many mid tones as you desire. This sorts out the white balance perfectly, every time.

To do it in camera - shoot a ref pic and set the white balance from that. It is a right fiddle at the time when you might be under pressure of time, whereas by using your AWB and then correcting back afterwards takes the pressure off at the time.
 
GEH007 said:
Taken 3 shots indoor under normal "lightbulb" light.

1 on Auto white balance, 1 on the tungsten setting and one setting manually using a grey lowepro divider to set the base.

The auto looks its usual dreadful self, the tungsten looks much less yellow but still artificial. The manual one looks like its been taken in natural daylight, almost a little cold looking.
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Taking the WB off a light blue card, shirt etc will warm it up. I'm using "warm" colloquially here, as a higher light temperature is more blue, or "cold" in ordinary speech.
 
HoppyUK said:
BTTT for this little gem of info. Never thought of that!
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Really great tip for determining exposure, but unless the grey is neutral, it won't give the best results for colour correction.

Anthony.
 
A few of points/tips to add to the mix...

Firstly, grey is better for WB than white as you run the risk of over-exposing the white which can lead to false results as the raw data in blown highlights might not be accurate. This is often seen in raw files where the recovered highlights lose their true colour. If you must use white under-expose a shot for WB purposes to ensure accurate results.

AutoWB is never right. To see this in action go outside in sunlight and take two shots, one of some grass and one of the sky. Import the files and check the WB in kelvin, they'll be different. AutoWB will give a different reading for every shot because it's based on the image data not the light. WB measurement should really be incident not reflected which is why the expo disk works so well because it is measuring the light directly and not reflected from the scene.

Also consider the colour of the light. If you've got a beautiful orange sunset then do you really want it to be "neutral"? Think about why you are using WB and if it will improve or ruin the effect of the light you are recording.

Got some Quality Street left over from Christmas? Get the wrapper from the yellow toffee finger and stick it over your flash to get a very good match between flash and tungsten light. It will kill a lot of the mixed lighting issues you get with using flash indoors, esp. if you're using fill flash. I took a custom WB on my 1DmkIII and keep it stored as setting #2 for quick access.

edit to add:

Click WB for Raw can also be a bit hit and miss unless you're sure the point you're clicking on really is a neutral grey (using white will have the same issues mentioned above). There aren't many things in the real world that are truly neutral grey so all you're really doing is given the image the inverted colour cast of whatever you clicked on - click on something with a yellow cast and you'll get a blue cast in the image.
 
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