These grey cards and white balance questions.

[Klickit]

After some discussion in another post, Myra said:

Kit, I thought you had to set a custom white balance "in" the camera, too, so never got around to fiddling with it. Thank goodness these guys keep nudging us in the right directions:0

This somehow rang a bell that once, a long time ago, I bought a white balance cap thingy. It went into a bottomless pit somewhere as I couldn't work out how to use it. I just went and found it and then looked at yet more stuff on the interwebs and yes, you can save a white balance in a D80 and presumably most other reasonable DSLRs.

On a D80, you do this: Fit your white balance cap on the end of the lens. Then you set the white balance to "Pre" - stands for preset - using either the menu or by depressing the WB button and scrolling the back wheel. You depress the shutter half way while holding the white balance button in and on the top lcd screen you see the usual exposure and f/stop info and a flashing "PRE". Still keeping the shutter held half depressed, attach the white balance cap and fully depress to take a shot through the cap. If the shot is suitable, you will see "Good" come up in the top lcd screen. This then sets and stores the white balance for the particular light at that time. So all your subsequent shots for that particular lighting will theoretically be correct for white balance.

I'm assuming that you can do the same with either a white or a grey card, but a more knowledgeable person will have to come along and confirm/deny that.

Seems to me that by mastering this, you can save a lot of time in pp, as you don't have to correct a lot of dodgy white balance.

But you would have to remember to re-set the WB for each shooting session.

Please note that I haven't tested this yet, as it is night-time. But I'll have a go at this during the day tomorrow and get back.

I hope I have all this right and am quite happy to be corrected.

[Colin Southern]

Hi Kit,

On a D80, you do this: Fit your white balance cap on the end of the lens. Then you set the white balance to "Pre" - stands for preset - using either the menu or by depressing the WB button and scrolling the back wheel. You depress the shutter half way while holding the white balance button in and on the top lcd screen you see the usual exposure and f/stop info and a flashing "PRE". Still keeping the shutter held half depressed, attach the white balance cap and fully depress to take a shot through the cap. If the shot is suitable, you will see "Good" come up in the top lcd screen. This then sets and stores the white balance for the particular light at that time. So all your subsequent shots for that particular lighting will theoretically be correct for white balance.

Not quite - it's vital that you point the camera back towards the light source, as that's what you're trying to neutralise the colour temperature of; if you point it at - say - a red fire engine and do a custom white balance you'll subsequently end up with a gray fire engine!

I'm assuming that you can do the same with either a white or a grey card, but a more knowledgeable person will have to come along and confirm/deny that.

In theory yes, but in practice it's not always that easy because you usually need to fill around 80% of the screen with the card, and with a wide angle lens, that means getting REALLY close ... but if you get really close, you can end up shading the card, or introduce other biases (eg light reflecting from clothing).

Seems to me that by mastering this, you can save a lot of time in pp, as you don't have to correct a lot of dodgy white balance.

Not really. If you include a reference shot in a series of RAW shots then you simply open them all - select the shot with the gray card - white balance it (1 click) - select all images - and then synchronise the white balance. You can accurately whitebalance several hundred shots in less than 1 minute.

But you would have to remember to re-set the WB for each shooting session.

Yes - but it gets even worse ...

... if you're using fill flash (which is pretty essential for any quality portraiture) then you end up with a mixed colour temperature environment ... and that's something products like the ExpDisc ("white balance cap") can't handle as there's no way to include the flash portion of the exposure in the reference shot, whereas with a gray card it works just fine. For what it's worth, I own 2 Expodiscs ... and NEVER use either of them

[Ashwin]

Hi Colin, Hi Kit,

White balancing is a tricky issue.

No method is full proof.

Whatever method you choose, for fine tuning you have to do some adjustment in post production. Otherwise you have to be satisfied with the result you have got.

Taking reference from one picture, and setting white balance for whole lot. I dont agree with this method, yes under the identical condition you may get acceptable result but never perfect or near perfect white balance.

If your camera is set for ourdoor setting, or auto white balance., and you are also taking picture outdoor. Still you may not get correct picture, if your subject is in shadow.

Here I will give one example of photographs posted here by Myra. He has set his camera on auto white balance, taken photographs in daylight but his subject is in shadow, this is the reason his pictures have cyan cast.

[Colin Southern]

Taking reference from one picture, and setting white balance for whole lot. I dont agree with this method, yes under the identical condition you may get acceptable result but never perfect or near perfect white balance.

Hi Ashwin,

I use this method for studio shots all the time ... with perfect results.

At the end of the day, if it's accuracy that you're after then if the temperature of the light doesn't change then the compensation temperature won't change either, and the same correction can be applied to however many shots were taken under lighting of that temperature. Admittedly, most people probably wouldn't do several hundred like I do though, but I get away with it because of course studio lights are 100% constant temperature.

[Ashwin]

Hi Ashwin,

I use this method for studio shots all the time ... with perfect results.

At the end of the day, if it's accuracy that you're after then if the temperature of the light doesn't change then the compensation temperature won't change either, and the same correction can be applied to however many shots were taken under lighting of that temperature. Admittedly, most people probably wouldn't do several hundred like I do though, but I get away with it because of course studio lights are 100% constant temperature.

" Taking reference from one picture, and setting white balance for whole lot. I dont agree with this method, yes under the identical condition you may get acceptable result but never perfect or near perfect white balance. "

Hi Colin,

You are right, I fully agree with you.
In your Studio, your light source is constant and
" UNDER THE IDENTICAL CONDITION " you are taking shots, that's why this is possible.

If somebody, takes shots outdoor in day light, say for example in the garden where there is Sunlight and some areas have Long shadows, or some area is covered but there is bright light. In sort with variation of lighting conditions you get different colour temperature, and that demands proper white balancing.

MY POINT IS You can't have one adjustment for all the pictures taken in different conditions, still if you do that you will end up with some degree of colour cast on some of them.

[Klickit]

Hi Kit,



Not quite -


In theory



Not really.



Yes - but it gets even worse ...

Ah.

Well, it's a good job I didn't pay too much for that pesky white balance cap, then isn't it?

Thanks for the updates, guys.