White Balance with Flash - how set?

lifeinfocus

Question about setting white balance when using flash.

I have gotten into a habit of manually setting white balance with a grey card.

I have often taken a photo of grey card with a flash and then in post processing using the eyedropper on the grey card.

Can white balance be set using preset manual with flash like I often do with a grey card and ambient light?

Can white balance be set with a grey card when using flash? If so how?

Thanks, Phil

pathfinder

Use the grey card, or better yet, a neutral white, non-specular card in your image, lit in the same manner as your subject. Then in PS or LR, click on the card area, with your color balance eye dropper for your color balance setting.

Most grey cards are for exposure setting, not really neutral for color balance. Canon manual suggests setting a custom white balance with a white card - non-specular.

lifeinfocus

pathfinder wrote: »

Use the grey card, or better yet, a neutral white, non-specular card in your image, lit in the same manner as your subject. Then in PS or LR, click on the card area, with your color balance eye dropper for your color balance setting.

Most grey cards are for exposure setting, not really neutral for color balance. Canon manual suggests setting a custom white balance with a white card - non-specular.

Thank you. That is what I have been doing.

I don't expect to be able to set WB with flash as I do in continuous or ambient light, but I was just wondering if I could. The method I am speaking of is to set the grey card in a position that captures the light as it would be in the shot, switch to manual focus, get very close to the card, and use the manual WB setting on my D700. Doing that requires that I hold down the WB button until I get "GD" response from the camera.

I supposed that would not be doable with flash because I would have to be holding the WB button and press shutter to release the light.

I tried my modeling flash function while trying to use preset manual WB. That did not work.

Anybody else have an idea how to do it?

BTW, I read on "Stobist" that he "I almost always shoot on daylight white balance when shooting flash." Then suggest adding a warming gel "I like a 1/4 CTO".

I am trying to just use the preset manual WB feature.

Thanks,
Phil

kdog

pathfinder wrote: »

Use the grey card, or better yet, a neutral white, non-specular card in your image, lit in the same manner as your subject.
[...]
Most grey cards are for exposure setting, not really neutral for color balance. Canon manual suggests setting a custom white balance with a white card - non-specular.

Jim, you may have missed the note in the manuals that says the use of a "commercially available" 18% gray card can produce more accurate results for white balance than a "white object". I think the only reason they mentioned a white object is that they're assuming not everyone has a gray card.

pathfinder

The grey patch in a Color Passport will certainly work, I agree, Joel. I just have some reservations about assuming all 18% grey cards are truly color neutral. In my mind, at least, 18% grey cards are for exposure measuring, not color balance.

When I tested several grey cards for this thread - http://www.dgrin.com/showthread.php?t=90438 - I found them somewhat less than perfect in a neutral color balance sense… They were close, but not truly neutral.

Do you have a link for the specific manual that recommends a grey card?

kdog

Jim, I'm traveling right now, but check page 137 of your 5DMKIII manual, second bullet if i remember. correctly. Pretty sure all the Canon bodies have the same text. I think white objects can also have accuracy issues.

Sent from my HTCONE using Tapatalk

ziggy53

The following is specific to the OP question of white balance and daylight-corrected, flash-based lighting.

The problem with using white cards/targets and uninformed users is that proper exposure can lead to channel-clipping of the white card, which can seriously skew the WB results.

You need to underexpose a white card/target in order to prevent the clipping. If you do that, underexpose to prevent the clipping, you will get potentially better results than you can get from a gray/grey card. The reason is that a gray/grey card will not necessarily deliver as much data as a white card/target, especially at lower light levels. Less data can amount to less accuracy, especially in tungsten lighting.

So, to summarize, if you underexpose a white card/target enough to prevent channel clipping, then a white card/target delivers more data with potentially better accuracy, compared to using a gray/grey card.

A gray/grey card simplifies the process by eliminating the need to underexpose, which means an easier procedure and process, but with potentially less accuracy.

Either method, using a white card or using a grey/gray card, should yield better results than guessing, however.

I tend to use either a "daylight" or a "flash" WB setting in RAW conversion software, depending on the ambient light circumstances and ambient contribution. Then I use iCorrect Portrait to "color correct" the whites and blacks and skin tones in the scene (when applicable).

Remember that you may "always" use your own palm as a source for both exposure* and for color balance, and that color balance is often more important than white balance in a scene with flesh tones. (In scenes without flesh tones, absolute white balance is often unnecessary, and you can use a color corrected monitor to correct the scene to "pleasing" colors instead.)

*(A typical human palm is generally exposed 1-stop over a gray/grey card for proper exposure for an "average" scene of limited dynamic range.)

kdog

Ziggy, wouldn't overexposing a gray card be equivalent to underexposing a white card?

kdog

kdog wrote: »

Jim, I'm traveling right now, but check page 137 of your 5DMKIII manual, second bullet if i remember. correctly.

Page, 139 actually. I was close.

pathfinder

Joel, I do not have the manual for the 5DMkIII, but I do have the manual for my 1Dx, and on page 139 it says "Instead of a white object, an 18% grey card can produce a more accurate white balance" even though the same manual recommended using a white object at the top of page 139. Go figure!!!

I think Ziggy gave the best answer, in that a white object, non specular, that is not over exposed, provides more data than a grey card that, accurately exposed, should be in the middle of ones histogram. Both a grey card or a white card might not be truly neutral in all channels as I demonstrated in my earlier link. But both are close enough for government work, I think, if used properly.

Lastolite makes a non-specular 18% grey reflector that I like quite a bit because it is large enough to fill ones viewfinder, and if shot in Av mode, provides a fine slender spike in the exact middle of one's histogram. Hence one has the proper exposure settings from this image. One can then use this same image to set a custom white balance in the camera, since is it a neutral 18% grey. Very cool device and quite useful. You get color balance and proper exposure at the same time. What is not to like about that?!

I should also add, that color balance is ultimately not a technical question, as the color balance of an image is really an artistic decision, not a technical question….. The final color balance is the one that looks best to the artists eye. But getting good skin tones is helped by using a custom white balance tool of some sort, usually.

ziggy53

kdog wrote: »

Ziggy, wouldn't overexposing a gray card be equivalent to underexposing a white card?

The pigments used to create the gray/grey tones are rarely going to be truly equal for all color channels (RGB). It's just easier to create a color neutral white card/target than it is to produce a color neutral gray/grey card/target (not that all white card/targets are created equal either).

You are correct in that overexposing a gray/grey card/target should provide more RGB data, and potentially more accuracy, versus a properly exposed or underexposed gray/grey card/target.

kdog

pathfinder wrote: »

Lastolite makes a non-specular 18% grey reflector that I like quite a bit because it is large enough to fill ones viewfinder, and if shot in Av mode, provides a fine slender spike in the exact middle of one's histogram. Hence one has the proper exposure settings from this image. One can then use this same image to set a custom white balance in the camera, since is it a neutral 18% grey. Very cool device and quite useful. You get color balance and proper exposure at the same time. What is not to like about that?!

Are you talking about this one, Jim? http://www.amazon.com/Lastolite-LL-LR1250-12-Inch-Ezybalance/dp/B0009QZDL6

I have that one myself. It has white on the backside too which is nice. The other day I compared the WB from the gray side to the white side on the ambient light in my office and they were virtually identical. Same temp, and the tint had a difference of just 1. Close enough for me!

pathfinder

Yes, that is it, Joel. Handy tool.

I looked at the manual for my 7D on pages 71-72, and it is the same as the 5DmkIII and the 1Dx. At the top it describes using a white object for a custom white balance, but then adds at the bottom of page 72 in grey, that an 18% grey card can offer a more accurate white balance. As you said, both seem to work quite satisfactorily.

kdog

Interestingly, here's an article with some reasons to favor gray targets over white for WB. http://www.rmimaging.com/information/gray_or_white.html

lifeinfocus

Thanks to all for your comments. I use the Lastolite grey card noted by Joel, so that is one plus.
My original question was really more about the method of manually set white balance.
I am using a Nikon D700. For Nikon the manual method of setting white balance is a five step process.

1. Light reference object - grey card, etc. Note that exposure is automatically increased by 1 EV when measuring white balance; in exposure mode M, adjust exposure so that the electronic analog exposure displays shows ±0 "
2. Set white balance to Pre (preset manual). "Press the WB button and rotate the main command dial until Pre is displayed in the control panel"
3. "Release the WB button briefly and then press the button until the Pre icon in the control panel and viewfinder start to flash."
4. "Before the indicators stop flashing, frame the reference object so that it fills the viewfinder and press the shutter-release button all the way down. The camera will measure a value for white balance and store it in preset d-0."
5. "If the camera was able to measure a value for white balance, GD will flash in the control panel..."

So, the question is can this be done with a flash if in step 3 above when Pre is set? Or is that done in step 4 when the shutter release is pressed and the flash is fired?

And how does this differ when flash is on camera vs. one or more off camera?

Sorry for such a long question, but for some reason it just doesn't seem to make sense that it would work with a flash.

Thank, Phil

kdog

Phil, I'm not a Nikon shooter, nor do I set my WB in-camera; I keep it simple and shoot a gray card during my session and set WB in LR. However, I think I see what's going on here. In step 4 it sounds like the sample is taken when the shutter is pressed and hence when your flash is fired. You can have one on-camera light or 10 off-camera lights, doesn't matter. Your gray card will be illuminated with whatever lights you're using and the WB will be now set. Experiment with it and see it if works. If you use LR or PS/ACR, you can easily check the result with the WB dropper and compare it to your "as shot" WB. Or send me a file and I'd be happy to measure it.

pathfinder

lifeinfocus wrote: »

Thanks to all for your comments. I use the Lastolite grey card noted by Joel, so that is one plus.
My original question was really more about the method of manually set white balance.
I am using a Nikon D700. For Nikon the manual method of setting white balance is a five step process.

1. Light reference object - grey card, etc. Note that exposure is automatically increased by 1 EV when measuring white balance; in exposure mode M, adjust exposure so that the electronic analog exposure displays shows ±0 "
2. Set white balance to Pre (preset manual). "Press the WB button and rotate the main command dial until Pre is displayed in the control panel"
3. "Release the WB button briefly and then press the button until the Pre icon in the control panel and viewfinder start to flash."
4. "Before the indicators stop flashing, frame the reference object so that it fills the viewfinder and press the shutter-release button all the way down. The camera will measure a value for white balance and store it in preset d-0."
5. "If the camera was able to measure a value for white balance, GD will flash in the control panel..."

So, the question is can this be done with a flash if in step 3 above when Pre is set? Or is that done in step 4 when the shutter release is pressed and the flash is fired?

And how does this differ when flash is on camera vs. one or more off camera?

Sorry for such a long question, but for some reason it just doesn't seem to make sense that it would work with a flash.

Thank, Phil

Like Joel, I still remain faithful to Canon ( kind of like being a red headed step child these days I know ) but to set a custom white balance in the Canon world is a very easy task. You simply hold up the Lastolite white balance target, shoot a jpg with your camera in Av mode, and then in the menu in the camera, tell the camera to use that grey jpg to set a custom white balance. It is actually easier to do, than to describe. Less than 30 seconds after you have done it once or twice.

chrisjohnson

Very useful advice all around. I just ordered a Lastolite even - about time I took white balance more seriously ...

Silly question probably, but if you want to go for getting it right in-camera, should you shoot the Lastolite with flash or without to make the custom setting?

Secondly, I wonder how to handle with Aperture? I find it very difficult to correct RAW flash images when the colour is too far out. Especially when reflected flash is collecting colour from, say, a painted wall.

Any tips are very welcome because I am just starting to learn how to do this properly.

pathfinder

Chris, I think if you are going to use flash in a studio situation, where there flash to ambient ratio is consistent, and flash is not being bounced off of various colored articles in the environment, then you can use a white balance obtained with a Lastolite color balance tool incorporating the flash lighting, as a jpg for a custom white balance.

But - if the amount of flash is going to be varied at all, then I would just incorporate a grey card, or a ColorPassport in each series of images and use white balance tool during image editing in Photoshop.

Bare in mind, that the final color balance of an image, is an artistic decision, not a technical one, and can only be established finally by the artists eye, not a technical tool.

arodney

pathfinder wrote: »

Joel, I do not have the manual for the 5DMkIII, but I do have the manual for my 1Dx, and on page 139 it says "Instead of a white object, an 18% grey card can produce a more accurate white balance" even though the same manual recommended using a white object at the top of page 139. Go figure!!!.

IF you capture JPEG, gray balance is fine. It's gamma encoded. If raw, white balance is preferable. Half of all the data is contained in that first stop of white data. You can gray balance but depending on the scene and other variables, you could end up with a color shift using gray instead of white. The important aspect of either is they are spectrally neutral which many products are not! The X-rite Passport is a good target for either kind of balancing.