AWB Surprise

[Philinflash]

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Phil - The only thing that confuses me is what your understanding of the word 'Auto' means in AWB, and what 'As Shot' means in the conversion software. One doesn't make in-camera adjustments to the WB when using the AWB setting...so the values in 'As Shot' would quite logically be those that the camera supplied as an automatic white balance.

 

I realize that this might be much too much time to spend on something most of us claim to not care about.

 

Peter, I regard AutoWB as a WB option selected by the camera user. Of course, the color balance selected by the FW will vary from situation to situation when shooting in JPEG mode. If the camera user selected a WB option other than AWB, then the file will reflect that choice. And I agree that the As Shot values would be those that the file carries with it from camera to computer, whether AWB or one of the other options.

 

The options other than As Shot offered by your PP software are essentially stored presets of the color balance adjustments that the software then applies. Whether or not the camera user elected AWB prior to the exposure or other WB camera options, your PP software will either do nothing further with regard to WB (in As Shot) or will make adjustments to the WB if one of the other WB options are selected.

 

Not all PP software offers WB presets. For instance, Adobe Bridge CS3 gives you three WB options: As Shot, Auto, and Custom. As Shot does nothing to the WB, Auto changes the WB in some stupid unusable way (probably assuming the lightest value is meant to be white and taking out any image color that does not conform to that assumption), and Custom allows you to move two sliders to input the values you want, previewing as you go.

 

Therefore, shooting in JPEG you get two bites of the White Balance apple: before you shoot (with the camera FW options) and after (with the PP software options).

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[pthompson]

Not all PP software offers WB presets. For instance, Adobe Bridge CS3 gives you three WB options: As Shot, Auto, and Custom.

 

Phil - The source of our confusion is that you are processing JPGs and I am working with DNGs (RAW). You are getting 3 options in CS3, and I am getting 8 or 9. Your As Shot option doesn't give you the actual AWB value from the camera, but rather a zero from which you can adjust + or -, whereas I am getting the actual temp and tint values from the camera...and my point is that I was amazed to find that there are only three possible sets of values supplied, no matter what the actual light conditions. I am certain that your zero also represents these three possibilities, but I can't remember if there is any way to check that. The other presets that are offered by the camera and by the software are not relevant to the point of my post.

[Philinflash]

Phil - The source of our confusion is that you are processing JPGs and I am working with DNGs (RAW). You are getting 3 options in CS3, and I am getting 8 or 9. Your As Shot option doesn't give you the actual AWB value from the camera, but rather a zero from which you can adjust + or -, whereas I am getting the actual temp and tint values from the camera...and my point is that I was amazed to find that there are only three possible sets of values supplied, no matter what the actual light conditions. I am certain that your zero also represents these three possibilities, but I can't remember if there is any way to check that. The other presets that are offered by the camera and by the software are not relevant to the point of my post.

 

No, actually I only rarely shoot JPEGs but I agree that Bridge gives more WB options on a DNG file along with the temp and tint as you say.

 

But I am finally getting your point and I now see what you mean. There is not a continuum of WB adjustments applied to the file when shot AWB as one might reasonably expect; but rather it is just these three benchmark settings which are quite far apart from each other and are actually quite gross. Now that I get it, I see the same pattern in my DNG files that I hadn't seen before. Part of my problem in recognizing the problem is that I use the non-AWB camera settings quite a bit, so I was unconscious of the clustering that goes on in AWB. And, of course, it all comes into Bridge "As Shot" regardless of my settings. I guess that is why I wind up adjusting WB in post in so many of my shots. Thank God the software is there to bail me out.

 

Thanks, Peter, for bringing this up and I apologize for being so slow in taking the point you are making. It is an excellent observation on your part.

[pthompson]

There is not a continuum of WB adjustments applied to the file when shot AWB as one might reasonably expect; but rather it is just these three benchmark settings which are quite far apart from each other and are actually quite gross.

 

Thanks, Phil; glad we are on the same page.

 

The thing that I find interesting (aside from the fact that Leica would give us such a system) is the way we all were talking about this - that the AWB was all over the place...when the problem is precisely that it iSN'T. It is only in three places, while the light we are trying to measure IS all over the place. Sort of like, when the sun sets, we talk about the shadows as disappearing, when they actually remain while everything else goes into shadow. Oh, and the sun doesn't actually set.

 

My head hurts - I'm going to go take a nap.

[mweiner]

As a newbie, I'm confused about some basic issues

by what I've read here.

People say, "I shoot raw, so I don't worry about what the camera

does with WB." And this is what I thought -- that whatever

the WB setting in the camera (auto, tungsten, daylight),

the DNG files I open in C1 or ACR, would have the same

information. However, some of what I interpret in this thread

suggests that the information in the DNG file varies with the camera's WB setting.

 

My question is: If I make images under florescent lighting

with the M8 set to tungsten, will the resulting DNGs be

less good/accurate/useful for post-processing

(eg adjusting WB using a Whitbal card) than if I had

set the camera WB to florescent -- and why or why not?

 

Also, would the DNG's captured under florescent light

with camera WB setting of tungsten look the same

as thumbnails when opened by C1 as they would

if the camera WB were set to florescent -- and why or why not?

 

Thanks in advance for any clarification.

 

Michael

[mjh]

People say, "I shoot raw, so I don't worry about what the camera does with WB." And this is what I thought -- that whatever the WB setting in the camera (auto, tungsten, daylight), the DNG files I open in C1 or ACR, would have the same information. However, some of what I interpret in this thread suggests that the information in the DNG file varies with the camera's WB setting.

The DNG contains roughly two kinds of data: image data und metadata. The raw image data are unaffected by whatever white balance setting is chosen by the photographer or the automatic white balance, so in this sense, the DNG contains the same information regardless of the WB setting. This implies that when the AWB or you have made a mistake, this is completely recoverable at the raw conversion stage.

 

However, beside the image data there are also various kinds of metadata, among these the WB setting chosen by the AWB or by you, the photographer. When you select “WB as shot” in the raw converter, the software will use this value. But you can still choose any other WB setting; you are in no way limited in your choice.

 

If I make images under florescent lighting with the M8 set to tungsten, will the resulting DNGs be less good/accurate/useful for post-processing (eg adjusting WB using a Whitbal card) than if I had set the camera WB to florescent

No, they won’t (see above).

 

Also, would the DNG's captured under florescent light with camera WB setting of tungsten look the same as thumbnails when opened by C1 as they would if the camera WB were set to florescent

No, because with raw converter would use the “as shot” setting initally. But that doesn’t affect the outcome of the raw processing in any way.

[Philinflash]

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As a newbie, I'm confused ...

 

Gee, Michael, I don't know why. But, seriously, this is confusing stuff.

 

Simply, if you shoot in DNG, you do not need to worry too much about your pre-shot WB settings. However appropriate or inappropriate your WB settings are, they will only carry over to post production to appear "As Shot" in your ACR processing software. You can change that to any of the presets offered by the software or any "Custom" setting that floats your boat without altering the basic contents of your image file.

 

There are some problems, however. For instance, unless you have color-metered the scene you shoot, will not have the true color temperature of the scene for later reproduction, should you want it. You will have to rely on your color memory or just PP aesthetics. Some people say you can use the Manual WB feature with a product like an Expo Disk to get equivalent in-camera metering but I would not trust the M8 to do that well.

 

In Peter's original posting on this thread, he shared his observation that 1 of 3 different and arbitrary WB settings will be applied if you shoot having selected AutoWB. This can result (and has for me) in otherwise-similar exposures having different WB metadata that go with the image file to post production. This can be inconvenient if you fail to notice the differences in PP and to make the appropriate compensations. Therefore, it is almost certainly better to shoot in any WB option EXCEPT AWB because then, at least, you will be dealing with just one set of WB metadata for all your shots so they will look consistent on first importation to your PP software.

[mweiner]

Michael and Philip,

 

Thanks for clearing this up for me.

 

M.W.

[Ronazle]

Hi. I hope this is not too far off track, but one of the expectations of picking a descriptive (i.e., daylight, tungsten, etc, etc,)white balance is getting a photographer's expected kelvin temp adjustment. How come tungsten yields color temp adjustment far, far from 3200K or 3400K. I guess the Leica people decided it would be better to balance for some artbitrary home light bulb? Am I alone in noticing this? ron t.

[mjh]

How come tungsten yields color temp adjustment far, far from 3200K or 3400K. I guess the Leica people decided it would be better to balance for some artbitrary home light bulb?

Standard tungsten lamps have a colour temperature of about 2800 K, whereas halogen lamps have a higher colour temperature between 3300 and 3400 K. Most camera vendors have chosen halogen lamps as the reference for the tungsten preset, but some – Olympus, for example – have based the preset on the standard tungsten lamp.