Setting whitebalance with flash useing expodisk?

[RLipp69]

Can i set my whitebalance maually when i use flash with expodisk or am i better off just setting the camera on the lightning bolt in my whitebalace options?

[jefftaz]

You are better off with the expodisk between those two choices. Just set up your lighting and get your ratios how you want them. Then simply put on your expodisk and set your lens to manual focus. Stand where you want your model and aim back at the position the camera will be in while shooting. Fire your strobes as you shoot through the expodisk. You should see a gray picture recorded. Simply use that to set your white balance.

It is also recommend to shoot RAW as you can make any changes after the fact if it is not perfect.

Jeff

[Curtis N]

The Expodisc is designed to work in incident fashion, by putting the camera in the subject's position and aiming at the light source.

This works fine as long as your lights are off-camera, but it's pretty much impossible if you're using hotshoe-mounted flash.

For this reason, the Expodisc is not my white balance calibration tool of choice. I prefer neutral targets like the WhiBal card or the Ed Pierce calibration target.

[ShotByTom]

I have put the expodisk on and taken the picture with a mounted flash, camera pointed at the target, and it worked fine for me.

[Titus213]

I have put the expodisk on and taken the picture with a mounted flash, camera pointed at the target, and it worked fine for me.

So are you using the expodisk or the 'target' for white balance?

I would suggest something like Curtis recommends. I use a Lastolite collapsible 24" gray target which also flips for a small reflector. Greatly simplifies post processing.

[ShotByTom]

I went to a seminar where they had photographers representing expodisc. The way Curtis described is the proper way to use it, but...if you have less than ideal surroundings, you can put the disk on your lens and shot at your target, rather than back at your light source.

They demo'd this and it worked fine. They had a 580 on camera, another one to the side and tungsten lights overhead.

[sapearl]

I also have the Lastolite Easybalance - great for weddings and other social events. Most of my work is with the 580ex on a camera bracket so the Exposdisc would not be practical for my workflow.

The 5D prefers the white side of the Easybalance, so I "eyedropper" the RAW file and that gets things very very close.

So are you using the expodisk or the 'target' for white balance?

I would suggest something like Curtis recommends. I use a Lastolite collapsible 24" gray target which also flips for a small reflector. Greatly simplifies post processing.

[jrsforums]

I also have the Lastolite Easybalance - great for weddings and other social events. Most of my work is with the 580ex on a camera bracket so the Exposdisc would not be practical for my workflow.

The 5D prefers the white side of the Easybalance, so I "eyedropper" the RAW file and that gets things very very close.

Hi, Stu...

Actually, it is probably the RAW file that prefers the white side.

In Real World Camera Raw - CS3, Jeff Schewe states that 18% grey works fine for color balancing jpeg, but is too dark for RAW....if I remember correctly due to the linear space in ACR/LR. The better shade is 12%, which is what the Whibal uses....but if the white is neutral and works for you....great.

[sapearl]

Could very well be the case - I was just reading from the 5D manual though and they did not go into a whole lot of detail...... just a sentence or two. I was a little surprised finding that when I looked it up.;)

Hi, Stu...

Actually, it is probably the RAW file that prefers the white side.

In Real World Camera Raw - CS3, Jeff Schewe states that 18% grey works fine for color balancing jpeg, but is too dark for RAW....if I remember correctly due to the linear space in ACR/LR. The better shade is 12%, which is what the Whibal uses....but if the white is neutral and works for you....great.

[jrsforums]

Could very be - I was just reading from the 5D manual though and they did not go into a whole lot of detail...... just a sentence or two. I was a little surprised finding that when I looked it up.;)

Here's a post from our earlier conversations: http://photography-on-the.net/forum/showpost.php?p=4899059&postcount=10

[Titus213]

Now that is interesting info. Perhaps I should shoot both sides of the target.:lol: I do generally use the gray side and actually set the custom white balance in the camera with it. I've been very happy with the color so far, even under multiple light conditions. It sounds like I should use the white side if I'm going to correct in ACR.

[sapearl]

Well Dave, I'm not sure what to advise. I wasn't sure at first, so when in doubt go back to the camera's manual ;). In the instance of the 5D the book recommends the white side, although I have no doubt that I would probably get good results with the gray as jrs points out.

But doing a lot of wedding and event work, I figured a true photographic white would give me wanted I wanted for balance work to properly render bridal gowns. I've been doing it this way for about 18 months now and it works pretty well, albeit with occasional tweaking when I get into mixed light situations.

Now that is interesting info. Perhaps I should shoot both sides of the target.:lol: I do generally use the gray side and actually set the custom white balance in the camera with it. I've been very happy with the color so far, even under multiple light conditions. It sounds like I should use the white side if I'm going to correct in ACR.

[mnealtx]

If you're using it to set a custom white balance, it should work fine. As stated above, it may be too dark if you're including it in the first picture to be able to 'click' white-balance the photo set.

[JMHPhotography]

I have the Expodisc and use it most of the time. For situations where my flash is attached to the camera, I use a whibal. The Ed Pierce target works well too.

I did some testing between the Expodisc and whibal, and I also used a paint sample card which I got for free at home depot... just for fun. The results were that all three sources got my white balance in check, and they were about 25 degrees difference in each of the samples. The Expodisc was the warmest, the whibal was in the middle and the paint sample swatch was the coolest.

The reason I prefer to use the expodisc is that at the same time, I can not only get a good exposure reading, but I can also get perfect white balance... AND... on the 5D or any other full frame camera, I can get a profile for light falloff or vignetting. With that, in lightroom or ACR, I can make a perfect adjustment/correction for the vignette and apply it to all of my images that use that lens/focal length/f stop and correct vignetting. I did a dance school portrait session not too long ago with my 5D and 24-70 at 50mm and all pictures had some vignetting. I was able to use the gray frame to profile it and correct all of the files at the same time. It's a beautiful thing.

[sapearl]

Just goes to show that sometimes the least expensive, easiest to acquire solutions work the best. I doubt most brides could tell a 25 degree difference in color temp - heck, I probably couldn't :lol:.

Great test John..... thanks for sharing ;). - Stu

.....I did some testing between the Expodisc and whibal, and I also used a paint sample card which I got for free at home depot... just for fun. The results were that all three sources got my white balance in check, and they were about 25 degrees difference in each of the samples. The Expodisc was the warmest, the whibal was in the middle and the paint sample swatch was the coolest.

[PacAce]

Hi, Stu...

Actually, it is probably the RAW file that prefers the white side.

In Real World Camera Raw - CS3, Jeff Schewe states that 18% grey works fine for color balancing jpeg, but is too dark for RAW....if I remember correctly due to the linear space in ACR/LR. The better shade is 12%, which is what the Whibal uses....but if the white is neutral and works for you....great.
There is only a fraction of a stop difference between 18% gray and 12% gray. If 18% gray is too dark for RAW (whatever that means), then shouldn't the 12% gray be too dark, too? And what does the degree of darkness have to do with setting white balance? For setting exposure, I can understand that statement being made but not for white balance. For setting white balance, any neutral tone can be used as long as it's not clipped (white or black). Or am I missing something?

[Curtis N]

And what does the degree of darkness have to do with setting white balance?The way I figure, the brighter your target the higher the signal/noise ratio will be in those pixels, which should theoretically give the camera or RAW converter more accurate data on which to set the white balance (as long as no channels are clipped).

Of course you could take a black target (as long as it's truly neutral) and overexpose it to get the same brightness, but most people don't go to that much trouble when shooting a reference target for white balance.

As I understand it, that's the reason the WhiBal card is lighter than 18% gray.

[PacAce]

The way I figure, the brighter your target the higher the signal/noise ratio will be in those pixels, which should theoretically give the camera or RAW converter more accurate data on which to set the white balance (as long as no channels are clipped).

Of course you could take a black target (as long as it's truly neutral) and overexpose it to get the same brightness, but most people don't go to that much trouble when shooting a reference target for white balance.

As I understand it, that's the reason the WhiBal card is lighter than 18% gray.
I can buy that if we were talking about using a black card for setting white balance but the discussion was about 12% gray vs 18% gray. :|

[jrsforums]

I can buy that if we were talking about using a black card for setting white balance but the discussion was about 12% gray vs 18% gray. :|

It maybe an idealized case, but the lighter grey card is used because Thomas Knoll used it to standardize thw WB adjustment in ACR. The lighter card was used because the RAW images are processed in a linear color space. JPEG adjustments are OK with darker grey as their color space is on a tone curve.

The number of stops (exposure) has nothing to do with it. However, if we define white to black as the dynamic range of a camera, the 6% between 12% and 18% is about 1/2 stop....assuming a dynamic range of ~7 stops...if you assume higher or lower range the stop difference would vary with your assumption.

While we are on exposure, I am sure you are aware that 18% was an arbitrary number which Kodak decided on....and their claim was that it would be 18% before it faded), but no claim was ever made that it was neutral....that wasn't important at the time.

There are color cards on the market that have been tested for their neutrality....two I am aware of are, I believe, Whibal and WarmCards....Whibal having switched to currently providing only the lighter grey after first providing dark and light grey.

How important is this to get "technically correct" WB? To some, such as fabric and furniture photogs, very. To me, not really. I am going to adjust to how I remember or want the scene to look like. After all....who wants a beautiful late afternoon sunlit scene to have "technically correct" WB?

However, if I can, I like to have a known starting point. Putting a Whibal in an image of the scene (either before or after or with Custom WB....as long as the lighting doesn't change) will allow me to start any adjustments from a known base. And yes, you can get very acceptable results without a neutral grey card....we all have....and frankly all my snaps don't get a grey card....but they do get adjusted so I am proud of them.

BTW...the whole expodisk discussion is another "can of worms" which has been discussed ad naseum...to me, a waste of money.

[mnealtx]

All well and good, but the OP is discussing a custom white balance in-camera, not click-balancing in PP, which would make the entire discussion of 12% vs. 18% moot, would it not?

[Titus213]

All well and good, but the OP is discussing a custom white balance in-camera, not click-balancing in PP, which would make the entire discussion of 12% vs. 18% moot, would it not?

I am awaiting the answer to this with baited breath, 18% baited anyway.

I have been using this method (in camera) and have not had to adjust images beyond that.

[mnealtx]

I can tell you that I've used both the lighter and darker gray Whibal card for CWB and it makes no difference that I've seen.

If you're trying to click-balance, that very well may be a different story based on information up-thread.

[PacAce]

All well and good, but the OP is discussing a custom white balance in-camera, not click-balancing in PP, which would make the entire discussion of 12% vs. 18% moot, would it not?

Yes, that is exactly the point I wanted to get at also. What does it matter if it's 12% vs 18% if the WB is being done in-camera. They'll both expose to the same tone anyway when they are metered by the camera.

[jrsforums]

Yes, that is exactly the point I wanted to get at also. What does it matter if it's 12% vs 18% if the WB is being done in-camera. They'll both expose to the same tone anyway when they are metered by the camera.


If you guys would note....I was responding to Stu's post on using the eyedropper in RAW and having white work better than the dark grey. I didn't mean to "kidnap" the thread, but I guess I did...

As far as 12% vs. 18%, in camera you are working with jpeg for which I stated 18% works just fine.

Personally, I shoot RAW all the time. Even if I set a CWB, I still want the grey card image to check on when I bring them up in RAW. In fact, I will usually shoot the grey card before/after setting the CWB. This gives a lot of info on what the ambient WB really was (the "infamous" late afternoon sun :lol:).

[mnealtx]

Understood - but regardless, AS LONG AS THE TARGET IS NEUTRAL (caps for emphasis) it should make no difference if the reference is white, black or anything in between for click-balancing (assuming, as above, that it truly IS neutral and no channels are blown).

Using a gray card reference for exposure is an entirely different thing and is, as I recall, where the 12% vs. 18% argument comes into play.

Edit to add: I think you're talking more about using the gray card for midtone brightness settings via levels - that is the only place I can see it making a difference.

[jrsforums]

Understood - but regardless, AS LONG AS THE TARGET IS NEUTRAL (caps for emphasis) it should make no difference if the reference is white, black or anything in between for click-balancing (assuming, as above, that it truly IS neutral and no channels are blown).

Using a gray card reference for exposure is an entirely different thing and is, as I recall, where the 12% vs. 18% argument comes into play.

Edit to add: I think you're talking more about using the gray card for midtone brightness settings via levels - that is the only place I can see it making a difference.


No, I am talking about doing White Balance in Adobe Photoshop Camera Raw (or Lightroom). The advice on 12% grey is based, as I said, in matching what Adobe has used to create their WB....and that the color space for ACR is linear, which is much lower on the scale than tone corrected.

Generally, you are right that any neutral source will/should work....I am primarily reporting the info from Adobe, both via Schewe's book and the Adobe forums.

One thing all should be aware of is that "white neutral" will work. The problem many may have with "white" is that it is quite easy to "blow out" one or moe of the channels. As you might expect, this can play havoc with WB adjustments. (I suspect tha "black" might have similar problems, though I have no info to support this)

Last point....while there is much discussion on 18% grey vs. the "grey standard" of camera meters, I really do not worry about that. For exposure, I want the whites exposed as high as possible, without blow out (about 1/3 stop below OEW). After that, all my adjustmets will be to "taste". In addition....any hrey card used for exposure does not necessarily need to be neutral....but for setting a WB base (for doing creative adjustment to afterward) you need///or at least want....neutral....not all, actually few cards are.

[mnealtx]

I don't see how using a 12% or an 18% gray reference could make any difference in single-click white balancing within ACR or LR. Can you provide a reference to it?

[SkipD]

I don't see how using a 12% or an 18% gray reference could make any difference in single-click white balancing within ACR or LR. Can you provide a reference to it?I don't think anybody's saying that different percentages of gray have any effect as a white balance reference. The only thing that is important is that the gray is truly a neutral gray.

For metering light levels, the brightness/darkness of the gray card definitely makes a difference. However, with a given reflective light meter and any specific gray card one needs only to know how much bias to add/subtract to any reading.

[mnealtx]

No, that seems to be exactly what jrsforums IS saying... I'm asking for a reference because I've never heard of it and I can't see where using a 12% vs. an 18% gray would make any difference in white balancing.

[jrsforums]

No, that seems to be exactly what jrsforums IS saying... I'm asking for a reference because I've never heard of it and I can't see where using a 12% vs. an 18% gray would make any difference in white balancing.

I have referenced it twice in this thread:

http://photography-on-the.net/forum/showpost.php?p=4899059&postcount=10

http://photography-on-the.net/forum/showpost.php?p=4899059&postcount=10

In the ACR book, p 102-103, Schewe specifically talks about Knoll using the "...second-to-brightest swatch as the white balance sample point..." Then later says, "A 'graycard" that has traditionally been used by photographers in the past should be avoided because it's too dark, and traditionally, graycards aren't noted for their neutrality..." (note...since graycards were designed to exposure not WB).

[SkipD]

The fact is that, in practical terms, it does not matter what the level of gray is in a white-balance reference card as long as the card is, in fact, color-neutral.

Even a white card could be used as long as the exposure is correct so that none of the color channels get "blown out" in the image. If one meters on the white card and then shoots a reference shot for a custom white balance setting, the white card will appear as gray in that image, so that's fine (again, as long as the "white" card is truly color-neutral). However, putting a white card into a scene for correction in RAW conversion is risky because it's too easy to overexpose the white card in the scene.

[PacAce]

I have referenced it twice in this thread:

http://photography-on-the.net/forum/showpost.php?p=4899059&postcount=10

http://photography-on-the.net/forum/showpost.php?p=4899059&postcount=10

In the ACR book, p 102-103, Schewe specifically talks about Knoll using the "...second-to-brightest swatch as the white balance sample point..." Then later says, "A 'graycard" that has traditionally been used by photographers in the past should be avoided because it's too dark, and traditionally, graycards aren't noted for their neutrality..." (note...since graycards were designed to exposure not WB).

I'm sorry, John, but none of the references that you pointed out says that 12% is a better reference than 18% (or vice versa). (AAMOF, I couldn't find any reference to the either 12% or 18% anywhere in the copy of the book, for CS2, that I have.) Yes, the ACR book does say to use the 2nd lightest gray area in the chart but it doesn't say NOT to use any of the other areas. And, based on how I'm reading it, the reference to the darker "traditional" graycards not being neutral only speaks of the way those cards were manufactured, i.e. they were made for exposure setting, not WB setting. That, in itself, does not mean that a truly neutral 18% gray can not be used for WB as long as it really is neutral. And that can be easily be said of the 12% gray card, too. If the gray is not neutral, it doesn't matter how reflective it it, it isn't going to be really useful for accurate WB setting.

[jrsforums]

I'm sorry, John, but none of the references that you pointed out says that 12% is a better reference than 18% (or vice versa). (AAMOF, I couldn't find any reference to the either 12% or 18% anywhere in the copy of the book, for CS2, that I have.) Yes, the ACR book does say to use the 2nd lightest gray area in the chart but it doesn't say NOT to use any of the other areas. And, based on how I'm reading it, the reference to the darker "traditional" graycards not being neutral only speaks of the way those cards were manufactured, i.e. they were made for exposure setting, not WB setting. That, in itself, does not mean that a truly neutral 18% gray can not be used for WB as long as it really is neutral. And that can be easily be said of the 12% gray card, too. If the gray is not neutral, it doesn't matter how reflective it it, it isn't going to be really useful for accurate WB setting.

Leo....

In my prior post, I quoted from the ACR3, not ACR2, book, which specifically said, "...A 'graycard" that has traditionally been used by photographers in the past should be avoided because it's too dark..."

Now....where I come from, a traditional grey card is 18% grey....do you agree? So, it appears you should use something lighter. I cannot find the specific reference to 12%, which I believe was in the Adobeforums (which have a limited search engine), but something lighter and neutral is needed....12% works, as provided by Whibal (who stopped providing the darker grey card) and others.

Another reference is http://www.adobe.com/digitalimag/pdfs/ps_workflow_sec3.pdf

Here is a clip from that article...

[jrsforums]

Just for info, here are some videos that go through and explain the differences between Whibal and Kodak grey cards and white paper..

http://www.whibalhost.com/_Tutorials/WhiBal/03/index.html

http://www.whibalhost.com/_Tutorials/WhiBal/06/index.html

[mnealtx]

Ok, I think I found what you were talking about on the Adobe forums. Jeff Schewe is advocating using the second lightest gray on a colorchecker and making the implication that since that is the patch that Thomas Knoll uses for creating camera profiles for ACR that it is the best one to use for white balance.

At the end of the thread, another poster uses different values of gray for white balance with NO appreciable change, as show below:

I selected three of those images: the one, which was very close to overexposure (on the disk), one in the middle and one grossly underexposed, but the disk still usable.

I used the ACR WB picker to see the WB value evaluation.

In the darkest image it was 5000K-5050K, tint +7 to +9.
In the medium one: 5050K, tint +9 to +11; the very bright one: 5000K-5050K, tint +9 to +12.

The three shots yield the very same white balance.

How much was it in terms of exposure? The brightest was shot with ISO100, F/11, 1/400s and the darkest with ISO100, F/11, 1/8000s - that's over four stops.

In terms of raw pixel values: the green values (the limiting pixels) were between 3000 and 3200 in the higher exposed image, and between 110 and 135 in the image with the lower exposure (note, that the red values are between 60 and 85 - and still good enough). This corresponds to a less than 5% gray, yielding the same result as the white.

[PacAce]

Leo....

In my prior post, I quoted from the ACR3, not ACR2, book, which specifically said, "...A 'graycard" that has traditionally been used by photographers in the past should be avoided because it's too dark..."

Now....where I come from, a traditional grey card is 18% grey....do you agree? So, it appears you should use something lighter. I cannot find the specific reference to 12%, which I believe was in the Adobeforums (which have a limited search engine), but something lighter and neutral is needed....12% works, as provided by Whibal (who stopped providing the darker grey card) and others.

Another reference is http://www.adobe.com/digitalimag/pdfs/ps_workflow_sec3.pdf

Here is a clip from that article...
So, what this is really boiling down to is not whether a 12% or an 18% gray card should be used for WB setting but that, despite which neutral card is used as the reference, the exposure of the WB reference frame should be set so that the tone is very light (preferably as white as possible without clipping the highlight) to maximize the signal-to-noise ratio of the area that's going to be used as the WB reference in PP. That makes sense (to a certain degree although not completely) and I can buy that argument. But not the argument that a 12% gray card makes a better WB reference than a 18% gray (or vice versa). :)

[spkerer]

Just to note, in ACR the white balance dropper won't accept a click for white balance if the target has any channels blown. I don't know about Lightroom, but I would guess it behave similarly to ACR.