Custom white balance in camera

Simple question-- when you shoot a grey card on location in order to set your camera's white balance to custom, does the grey card need to fill the entire frame? Or just have the chosen af focus point in the center of it? How exactly should this be done?

It should be relatively large in the frame if not filling most. However, I long ago stopped bothering with even doing this. I just shoot RAW and I can change things later. I leave the camera on Auto WB and I don't really need to see the exact color on the preview that it will be. To each his own though. I just found it to be a waste of time.

It is not necessary to fill the frame with the grey card; all that's needed is that the card fill the center spot metering circle (not focus point).

RandMan wrote in post #16055744
Simple question-- when you shoot a grey card on location in order to set your camera's white balance to custom, does the grey card need to fill the entire frame? Or just have the chosen af focus point in the center of it? How exactly should this be done?

Gray Card…White Paper. What’s best?

In older models without spot metering Canon said fill the Partial area, now they say the Spot area.

CoPhotoGuy wrote in post #16055754
It should be relatively large in the frame if not filling most. However, I long ago stopped bothering with even doing this. I just shoot RAW and I can change things later. I leave the camera on Auto WB and I don't really need to see the exact color on the preview that it will be. To each his own though. I just found it to be a waste of time.

I agree, and the reason I'm asking is because I shoot RAW with AWB all the time just like you and have never come up with a logical reason to bother shooting a grey card. However, I'm shooting an indoor event tonight (flash, tungsten lighting) and find tweaking the WB even in RAW under those conditions to be a particular pain. The closer I can get initially the happier I'll be.

I assume that you're referring to getting it close in LR by using that gray card.

Mixed lighting can be a nightmare. It,s not too bad when it is only two sources, flash and one type of indoor light type. I was shooting at a muesum recently that allowed flash. The real problem was they had two diferent types of mecury vapour lamps, tungsten and LED. Fortunatly there were lots of nutural coloured surfaces to take WB readings from. The trick was to find the one that gave the best results for the subject. After that I used the targeted adjustment tool with the saturation slider to remove the colour casts from the other parts of the image. That of course desaturates the whole image, so I then used the local adjustment brush to add saturation back in as needed, followed by a general overall saturation boost gave me a pleasing looking result with fairly natural looking colours. This was done just using LR.

Alan

Interesting, I do a lot of in-camera custom white balancing but always tried to fill the frame with the gray card. Never heard that you don't have to do that, just the center section is enough.

So I tested on a Canon 5D3, and sure enough, just filling a small center section gives the same results as filling the entire frame. Tested under tungsten 2700k and natural 6700k light. Placed the gray card on a bright red shirt, so everything outside the center section shot was red and would throw the WB off if that outside area was used.

No problem using a small center section only. In camera WB matched custom WB in ACR exactly on temp and only 1 or 2 points difference in tint. Good to know.

Also, even though shooting raw I like to set in-camera WB because doing so makes the in-camera (jpeg) histogram a much closer match to the true raw.

That's the point that seems to elude those who advocate shooting with AWB and then adjusting in post production. They don't seem to realize that the choice of WB ifluences exposure.

If the only other color is tungsten then you just need a color correction gel to color your flash to match the tungsten lighting. THEN you can correct white balance easily in post because all the light temps are the same. Most camera stores will carry it. Very inexpensive too. Here's a good read.

http://strobist.blogsp​ot.de …sing-gels-to-correct.html

White balance for Canon is a sheet of white paper or equivilent. Gray card is for exposure.

I shoot jpegs almost exclusively and it works everytime. Fill the centre of the frame - at least the partial metering point. If you fill the whole frame, does it matter?

PixelMagic wrote in post #16057646
That's the point that seems to elude those who advocate shooting with AWB and then adjusting in post production. They don't seem to realize that the choice of WB ifluences exposure.

Exactly. I'm much happier looking at a preview (even though it's just a preview) and getting a decent representation of what my final image will be, rather than looking at something that feels strange but say, "Oh I'll just fix it later."

LincsRP wrote in post #16057699
White balance for Canon is a sheet of white paper or equivilent. Gray card is for exposure.

I shoot jpegs almost exclusively and it works everytime. Fill the centre of the frame - at least the partial metering point. If you fill the whole frame, does it matter?

That's not quite true; it all depends on the grey/gray card. There are several grey cards available that are specifically designed for setting White Balance like WhiBal, X-Rite ColorChecker Passport, and the Digital Gray Card from Robin Myers. While white paper might work in a pinch its not a reliable way to work since there's no guarantee of spectral neutrality as with grey cards designed for digital cameras.

It is true that in the past grey cards like Kodak's was used to determine exposure for film cameras but we aren't talking about the same thing here.

PixelMagic wrote in post #16057755
That's not quite true; it all depends on the grey/gray card. There are several grey cards available that are specifically designed for setting White Balance like WhiBal, X-Rite ColorChecker Passport, and the Digital Gray Card from Robin Myers. While white paper might work in a pinch its not a reliable way to work since there's no guarantee of spectral neutrality as with grey cards designed for digital cameras.

It is true that in the past grey cards like Kodak's was used to determine exposure for film cameras but we aren't talking about the same thing here.

If you read the Canon instructions it is. I'm not concerned with the commercial 'this is the right way' cards, I have read the canon instruction booklet and it does work.

If you want to follow the bunkum that white card manufacturers put out, then fine. I will follow my common sense and follow the canon booklet. It works.

For the price of a sheet of white paper I get a white balance. It works. I'm not interested in the past of Kodak with whatever they had, I'm only interested in what works today.

This isn't to say you don't have a valid point but it's what I use daily and get reliable results. You do appreciate jpegs shooters have a strong will, I presume