I assume many know this, but wanted to post about it "just in case."
With many (most?) modern digital cameras, it is possible to review the image after it is taken and either look at histograms or highlight warnings (the "blinkies") to help judge whether you achieved a good exposure on the shot.
If using histograms, you generally look to make sure that you aren't too far to the right. If using "blinkies," you make sure that nothing important to the shot is blinking on your LCD.
The caveat to both of these methods is that the "generic" setup (the white histogram or the RGB highlight warning) on many cameras only displays information from the green color channel. It ignores data from the red and blue channels. This is true for most point-and-shoots and is the default setting on Nikon bodies (can't comment on Canon). This is counter-intuative--one would think that the composite channel (or the RGB channel for cameras capable of displaying histograms for all three colors) would display a summation of clipping information obtained from all 3 color channels. This isn't the case. Instead only the green channel is displayed for reasons that escape me.
This is actually a fairly major design flaw, the importance of which depends on the colors present in your shots. For general shooting it often works. But you can get seriously screwed if the predominant color in your composition is red or blue, or if your composition has important highlights that are either red or blue. Relying on the RGB histogram or the presence of "blinkies" can create serious exposure problems in these situations. I have personally found this to be an issue when shooting red or blue flowers. The RGB (white) histogram looks fine and there are no blinkies on the LCD. I get back to my computer and find out that the red channel is completely blown out and the images are worthless.
This is easy to test out (assuming you have a body capable of displaying either histograms for each color and/or highlight clipping for each color ("blinkies")). Overexpose a shot of a red subject. Examine your "white" histogram (what should be the composite of the red, green, blue channels). Compare it to the histograms for each individual color. Or look at the "blinkies" for the RGB channel and then switch your LCD to display the R channel. Lot's more will be blinking now. The same experiment can be done with blue subjects.
Just wanted people to be aware of this. There is nothing worse than being on vacation and taking a picture of something where red or blue are important colors, the RGB histogram indicates a proper exposure (or you don't see any "blinkies" suggesting clipping) only to find out when you view it on your computer that you lost critical detail because the red or blue channel was actually overexposed and blown out, resulting in unusable images.
With many (most?) modern digital cameras, it is possible to review the image after it is taken and either look at histograms or highlight warnings (the "blinkies") to help judge whether you achieved a good exposure on the shot.
If using histograms, you generally look to make sure that you aren't too far to the right. If using "blinkies," you make sure that nothing important to the shot is blinking on your LCD.
The caveat to both of these methods is that the "generic" setup (the white histogram or the RGB highlight warning) on many cameras only displays information from the green color channel. It ignores data from the red and blue channels. This is true for most point-and-shoots and is the default setting on Nikon bodies (can't comment on Canon). This is counter-intuative--one would think that the composite channel (or the RGB channel for cameras capable of displaying histograms for all three colors) would display a summation of clipping information obtained from all 3 color channels. This isn't the case. Instead only the green channel is displayed for reasons that escape me.
This is actually a fairly major design flaw, the importance of which depends on the colors present in your shots. For general shooting it often works. But you can get seriously screwed if the predominant color in your composition is red or blue, or if your composition has important highlights that are either red or blue. Relying on the RGB histogram or the presence of "blinkies" can create serious exposure problems in these situations. I have personally found this to be an issue when shooting red or blue flowers. The RGB (white) histogram looks fine and there are no blinkies on the LCD. I get back to my computer and find out that the red channel is completely blown out and the images are worthless.
This is easy to test out (assuming you have a body capable of displaying either histograms for each color and/or highlight clipping for each color ("blinkies")). Overexpose a shot of a red subject. Examine your "white" histogram (what should be the composite of the red, green, blue channels). Compare it to the histograms for each individual color. Or look at the "blinkies" for the RGB channel and then switch your LCD to display the R channel. Lot's more will be blinking now. The same experiment can be done with blue subjects.
Just wanted people to be aware of this. There is nothing worse than being on vacation and taking a picture of something where red or blue are important colors, the RGB histogram indicates a proper exposure (or you don't see any "blinkies" suggesting clipping) only to find out when you view it on your computer that you lost critical detail because the red or blue channel was actually overexposed and blown out, resulting in unusable images.
