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DPChallenge Forums >> Tips, Tricks, and Q&A >> white balance setting
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08/26/2004 01:12:49 PM · #1
This weekend I took some pictures of Egrets in the wild along with Blue Herons. The problem is the white on my Egret is really blown out..The heron looks good. I have a digital rebel and want to know what I can do in the future to keep the white on the bird or other predominantly white creature from getting so blown out. I did step down on my exposure but that didn't seem to resolve the problem. The other thing I noticed was this purple fringing on the outline of the bird. Thanks for your help.
diana
08/26/2004 01:21:41 PM · #2
Can you post an example? If you shoot RAW then all the white balance problems disappear..kinda...you can adjust it in Photoshop afterwards.
08/26/2004 01:25:04 PM · #3
I asume that you´ve not been shooting in RAW mode. This purple fringing thing is a matter of JPEG compressoin artifact (I think). I´ve had this problem but very rarely.

One of the drawbacks of the Rebel is the center weighted average exposure and no point reading wich can make situations as you are describing here difficult. But that´s just one of the things we have to live with and learn to get around it.

I recomend shooting in RAW expecially in difficult situation since then you have lot more control in post processing expecially regarding exposure and white balance. Also it is more likely that computer probrams have better compression algorithms than your camera.

Hope it helps,
Garlic
08/26/2004 02:13:53 PM · #4
If your camara has a histogram, use it and place the graph as far to the right (bright) as you can, without blowing the highlights.

Otherwise, learn to meter on the lightest part of the image. This places that part of the image at middle grey, which isn't what you want so a bit of experimentation is needed to find out how much you need to 'over-expose' the reading to get the whites all the way to the right (without blowing them).

This can be done a number of different ways. I do it by setting the exposure compensation in-camera to +2 stops (what I have found is safe for my camera) and then meter on the white. If you can not meter exactly on the brightest spot of the subject (roo far, etc.) carry a white card to meter from (just make sure it is in the same light as your subject).

In situations where you are unable to meter on the white, this article ('The Ultimate Exposure Calculator') discusses learning to judge exposure without a meter and is quite helpful.

David

Message edited by author 2004-08-27 01:46:50.
08/26/2004 05:48:54 PM · #5
As you can infer from the other replies, the issue here is exposure, not white balance. I recommend setting the "Review" function to "On (info)", which will display a histogram of the image for a few seconds after each shot. Get in the habit of checking it each time. If it seems truncated on the right side and the brightest areas of the preview are flashing, the image is overexposed; set the Av setting down (negative) a bit and try again. (But note small specular highlights, like the glint of the sun from chrome, are acceptable.) On the other hand, if the right side of the histogram is zero and the left side is truncated, adjust the Av setting up to get detail in the shadows.

Be sure to return the Av setting to 0 when you are done! I'm always forgetting that, and don't notice until the next shot is unexpectedly under or overexposed.

There is a lot of speculation on the causes of purple fringing. My experience with the Rebel is that it seems to be mostly associated with overexposure, specifically in dark areas next to overexposed areas (such as tree branches against a bright sky). So hopefully if you get the exposure right, the purple fringes will go away.

Edit: I shoot in RAW and recommend it for most situations. But it isn't a cure-all. You don't have to worry about white balance, but it won't magically capture detail in overexposed areas, and it won't prevent purple fringing. It's also slower, an issue for photographing sports or flying birds when you want to get a lot of shots in quick succession.

Message edited by author 2004-08-26 17:53:54.
08/26/2004 06:43:34 PM · #6
Purple fringing isn't a JPEG artefact. It is a lens artefact and a sensor artefact, mainly due to the Bayer interpolation in most cameras. It is made worse by cheaper lenses due to flare and chromatic separation, but mainly it is caused by high frequency aliasing in the bayer sensor pattern. The result is that at the edge between a really bright and really dark part of a scene, the bayer interpolation screws up and gives you purple regions. It is also exacerbated by very bright highlights, which oversaturate the photo site. This is typically worse in smaller sensor cameras.

White balance will not help with blown highlights - this is purely an exposure issue.

White balance would help if for example the whites were too orange (warm) or too blue (cool)

When you mention that you stepped down your exposure, what was it you did to achieve this ?

RAW mode won't help a whole lot either, if you blow out the highlights.

The simplest solution is to expose correctly, in manual mode, for the existing light. This can be a hard balance to achieve, for example with white birds in bright sunlight, or a bride and groom where you want detail in the dress and the groom's suit.

Manual exposure, or metering, even with a center biased mode is relatively easy to learn. There are many books that cover it. John Shaw is particularly good at explaining ways to achieve good exposure, without needing to depend on fancy meter modes in a camera.

Message edited by author 2004-08-26 18:55:27.
08/26/2004 07:24:17 PM · #7
Originally posted by Gordon:


Manual exposure, or metering, even with a center biased mode is relatively easy to learn. There are many books that cover it. John Shaw is particularly good at explaining ways to achieve good exposure, without needing to depend on fancy meter modes in a camera.


I was just going to post this very thing when I came on your posting! I literally just read that section of John Shaw's Field Guide at lunch today and its one of the most intuitive explanations of how to expose I'd ever read. In fact I'm embarassed to say that I completely misunderstood how to use manual mode and spot metering on my D70 until I read that chapter.

Here's a link to the book I'm referring to - I highly recommend it!

John Shaw's Nature Photography Field Guide
08/26/2004 07:27:05 PM · #8
Originally posted by Gordon:

RAW mode won't help a whole lot either, if you blow out the highlights.


Presumably, you're referring to real clipping, which can't reliably be determined within the camera alone. Although the info preview mode provides the flashing highlights feature, it turns out that this visual cue is activated even before clipping occurs. That is, the flashing areas include those within (about) 1 stop of clipping.

If you've got a really good handle on exposure, you can stay in the safe zone in RAW with 1 shot. Barring that, bracketing is your one true friend.

Message edited by author 2004-08-26 19:27:17.
08/27/2004 08:49:11 AM · #9
Wow..good answers
I almost always shoot inRAW mode. The lens shouldn't be cheap because its the Canon EOS USM 75-300mm. I think Shaws book might just be the answer..thanks for the tip. I believe you all may of nailed it with the metering. Thanks again

diana
08/27/2004 08:53:19 AM · #10
I find the 300D prone to over-exposure. As such I nearly always shoot at -1/3 Ev, and on bright days down to -2/3 Ev.
08/27/2004 08:58:22 AM · #11
Originally posted by cghubbell:

Originally posted by Gordon:


Manual exposure, or metering, even with a center biased mode is relatively easy to learn. There are many books that cover it. John Shaw is particularly good at explaining ways to achieve good exposure, without needing to depend on fancy meter modes in a camera.


I was just going to post this very thing when I came on your posting! I literally just read that section of John Shaw's Field Guide at lunch today and its one of the most intuitive explanations of how to expose I'd ever read. In fact I'm embarassed to say that I completely misunderstood how to use manual mode and spot metering on my D70 until I read that chapter.

Here's a link to the book I'm referring to - I highly recommend it!

John Shaw's Nature Photography Field Guide


Yup. I second that, and would have 'firsted' it if I'd remembered what the book title was. The few pages on exposure is worth the cover price in itself for anyone struggling with the concepts of manual exposure and metering.
08/27/2004 08:59:06 AM · #12
Originally posted by dwoolridge:

Originally posted by Gordon:

RAW mode won't help a whole lot either, if you blow out the highlights.


Presumably, you're referring to real clipping.


Yes - I'm referring to blown highlights - which by definition are the clipped regions...
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