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DPChallenge Forums >> Hardware and Software >> White Balance Difficlulty with Canon Rebel XT
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Showing posts 1 - 14 of 14, (reverse)
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02/14/2007 03:51:57 PM · #1
I'm new to studio photography and I'm using a Rebel XT that I've had for a year. I'm finding that the white balance is very finicky. AWB gives me good results 8 out of 10 times. "Flash" setting makes everything too pink. The last time I used custom, everything came out bluish. Bottom line, I'm having difficulty in the blues/reds with my white balance. To compound it further, some of my shots come out a bit underexposed even though I haven't changed my light setup or shutter/apeture settings. It all looks fine on the LCD and I don't catch the problems until I get them on my computer. Any advice?

Message edited by author 2007-02-14 20:53:13.
02/14/2007 03:55:44 PM · #2
Did you actually set your custom white balance? Take an image of something white in the lighting you plan on using. Go into the menu settings till you find custom white balance. Set the custom to the white image you just took and you are set for that lighting set up. Or you can shoot in raw and fix it after...
02/14/2007 04:30:59 PM · #3
They are usually a little overpriced, but in the end, worth their weight in gold, but I would STRONGLY recommend getting a grey card. Once you get your lighting set up in your studio, they will be of limited use, but still great to have in the bag.

AWB is by definition finnicky. It will calculate white balance for each picture, and is bound to change.

If white balance is at all an issue, I always switch to RAW and shoot in one of the presets if there is no grey card available. I can then use Canon Digital Photo Professional to set a recipe for a correct white balance shift that can be the same for each picture. It doesn't really matter if the preset is not quite perfect, what is important is that each picture starts at the same point.

If done this way, it takes little time in post pro.

I've often found that having incorrect white balance can affect exposure by as much as a full stop usually in the wrong direction.

As toocool said, read your manual and learn how to actually set the custom white balance if you choose to use it. Using it correctly will help with the exposure issues.

Flash setting making everything come out too pink is a bit disturbing. Flash is usually pretty close to daylight, so if things are coming out pink, it might mean that your actual lighting is too magenta. Usually this is the other way round and shots come out too green if there is a bit of spillage from fluorescent lights.

As always, be diligent to eliminate light color mixing. Have all of your light come from the same type of source (flash usually mixes well with daylight as above).
02/15/2007 09:25:06 AM · #4
Thanks Toocool and Eschelar. I feel better knowing that the white balance can also cause underexposure. I thought I was either going nuts or didn't know as much about photography as I had assessed! I'm pretty confident in saying that my lights are not the problem. I have 2 800 watt Alienbees that I'm using. Once I set up my equipment and start shooting, I try to keep the subject in the same place. I'm very concerned about the pink tones resulting from the "Flash" setting. I literally had to adjust the color balance slider in PS a bit from Red to more Cyan.

I'll go back to the manual on the custum white balance. I may have misinterpreted the instructions.

Shooting RAW may be my best option until I get it all worked out. In the meantime, a greycard is on my shopping list!
02/15/2007 02:55:52 PM · #5
If you are doing studio work, there's pretty much never anything to be lost from shooting RAW. Might be a bit gained too. Depends a bit on your post DPP workflow.

Some of the advantages gained in shooting RAW are lost when you convert to JPG afterwards, so moving directly to tiff or psd or something that supports a large color space can prevent this.

I seldom bother with this myself as I'm simply lacking a need to go this extreme in color precision and range. If I were charging a lot more, I'd consider it a responsibility.

If you want to post some examples, we might be a bit better able to help you with the pink tones in Flash setting?
02/16/2007 09:03:25 AM · #6
Consider this photo below. I've already color corrected the image and then replaced the background color in PS with a brighter one. I shot this in JPEG but with this method, I have to correct each one individually in PS. I'm trying to avoid this. I don't charge clients much for my services so it's definitely not worth my time to rely heavily on post pro.

Check it out:


www.rittlerphotography.com/whitebal

Message edited by author 2007-02-16 14:03:46.
02/16/2007 09:06:09 AM · #7
Most (not all) studio strobes are daylight balanced.
02/16/2007 09:22:35 AM · #8
It's worth expanding on WHY the AWB can be "finicky"; in the same sesne that the camera's light meter averages all the tones within its scope and assumes they balance out to a zone 5 gray, thereby underexposing very bright scenes and overexposing very dark ones; in that same sense, AWB averages all the colors in an image and assumes that the "correct" balance of these would be neutral. So if you will the frame with a red wall and AWB that, it is NOT going to render as a red wall, but instead a much more neutral color. This is why we have to set custom WB off a neutral exposure, something that HAS no color when correctly balanced.

R.
02/16/2007 09:33:22 AM · #9
Originally posted by eschelar:

They are usually a little overpriced, but in the end, worth their weight in gold, but I would STRONGLY recommend getting a grey card.


Yes, you can get a gray card. But you can also save the money and go the handy-man/DIY way. If you have Word or any other word processor that lets you shade table cells, make a table one column wide by one row. Fill it with blank carriage returns until the one cell fills the entire page. Shade this to 20% gray in the options, print, instant gray card.

I have one of these I mounted on a self adhesive photo mount board trimmed to get rid of the border so it is entirely gray. I shoot a shot of this in planned light using the 'P' setting with AWB, then switch to custom WB, select shot as custom white balance and all is well.

The shot you take and select will not look correct in color, but every shot taken after that will. To check, after custom is set, reshoot the gray card and it should appear true to color so you know it is set right and working.

Also, you can use ANY color for custom WB. Just depends on what you want interpreted as white and on how you want your pics to come out.
02/16/2007 09:57:41 AM · #10
Hi Jessica,

I just looked at the example you listed, and yes, getting the WB right in the camera would be a huge asset, but, if you end up with shots like your example (see below) a very easy action could be recorded and batch run to correct them. Correction on this is as simple as Image, Adjustments, Match Color, and check the Neutralize box.

To record that, click on the action tab, click on the small arrow in the upper corner and select new Set, call it Match Color if you want. Then click on the arrow again and select new action, call it color matching for instance, then do the Image, Adjustments, Match Color, click the Neutralize box, then go back to the action tab and click the "stop" button next to the red record button. That will now stop the action you were recording, and it will be saved. From there, you can simply load all the images you want corrected or that need corrected into a folder, of their own, make a new folder as a destination, then go to File, Automate, batch, select the Match Color action previously recorded, select the source and destination folders, and run the batch process.

Feel free to PM me or reply here if you need help on this.

Edit to add thumbs to make it easier here to see changes:
-- to this -->

Message edited by author 2007-02-16 15:06:21.
02/16/2007 10:16:26 AM · #11
Brad,

What version of software are you using for this?
02/16/2007 10:18:51 AM · #12
Photoshop CS2
02/16/2007 10:27:56 AM · #13
Thanks so much, Brad. I need to upgrade to CS2. I'll save these instructions for when I finally upgrade. It's long overdue.
02/16/2007 11:45:45 AM · #14
I think the same options are available for CS as well, just not sure about previous versions of PS.
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