Underexposure and correcting it

Jul 18, 2010
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I posted a question [a href="http://www.thephotoforum.com/forum/photography-equipment-products-news-reviews/210585-canon-ef-70-300-usm-lens-maintenance.html"]previously about blurred pictures[/a] with some of the shots I was taking. I'm using a Canon 20D with a Canon 70-300 IS USM lens. I wondered if it was the lens causing the trouble or me, figuring it was most likely my inexperience.

Most of the comments alluded to underexposure. I also learned about EXIF for seeing the stats for the photos. I got an EXIF viewer and looked at some pictures I took in the last week. I've linked to 2 pairs to compare. It seems that all of them are underexposed, with the worse ones being more underexposed. Here are the photos:
This one is better than its paired photo. They were both taken in the same place at the same time, but this one is up in a tree and the other in on a lawn just below that tree.

This is the one I wanted to compare that to:

I was using autofocus for both and had the red lights in the viewfinder for focusing, but the Killdeer on the lawn still came out blurry.

This is the next pair. The first one came out ok.

But this one, the one I really wanted(!), didn't turn out as well.

I don't know what's causing the underexposure. All of the photos were taken during the day outside, not in direct sunlight usually. Do I have to start learning how to use the manual settings and make sure the exposure is working correctly? Or is there something about autofocus that I'm missing?
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buy this book [ame=http://www.amazon.com/Understanding-Exposure-Photographs-Digital-Updated/dp/0817463003/ref=sr_1_1?ie=UTF8&s=books&qid=1281213612&sr=8-1]Amazon.com: Understanding Exposure: How to Shoot Great Photographs with a Film or Digital Camera (Updated Edition)…[/ame]

as for the current jpegs if you still want them. whack them into photoshop, create a layer on top, fill it with white. change the layer to overlay and mess with the opacity so it looks in exposure.

It's good to learn the basics then you'll never have a problem like this again.

For the future, shoot in raw mode, this way if you bring it into photoshop you can adjust the exposure.
OPs images from above post:




I don't see anything too terribly out of whack with these images, other than slight underexposure. The blur in a couple of them I suspect is caused by slower than suitable shutter speeds (remember that your shutter-speed should be at LEAST the same as your focal length in APS-C terms, so: If you're using a 300mm lens on an APS-C sensored camera, your minimum shutter speed should be 1/450 of a second). This is one case where I think "Understanding Exposure" will actually help, 'though I'd check your local library for a copy first.
Two things strike me as less than ideal and might be worth thinking about:

1) The subjects are generally a very small part of the image, which is going to be difficult if you're trying to keep an AF point on them.
2) The EXIF data suggests that you are moving between modes "P" and "Landscape" and "Portrait" auto-exposure modes. These are probably not the best choices for the subject matter. Some reading of the manual (if you have it) and some of the tutorials here, and various books, might help make better decisions.

I generally agree with the above too. Nothing drastically wrong.
I agree that the size of the birds is a problem... It makes it difficult to keep a focus point on them, especially since they are moving. When I bought my first DSLR, I bought a model-specific book with it, and read it cover to cover, learning all of the features. You cheat yourself and your images a lot of the time when you use nothing other than the auto mode. When shooting in manual, you have complete control over shutter speeds. Read up on it a bit, and keep trying, it will get better the more you learn.

Your camera's exposure system is working fine and your photos are not underexposed.

You should continue to use your camera and trust it's metering system; in other words use the camera's P and/or Tv and Av modes. In your case the Tv mode makes sense because you've got a 300mm lens. In the photo of the red and blue bird for example your shutter speed was 1/200 sec. You can't hand hold that 300mm lens and expect sharp photos at 1/200 sec -- tirediron is correct in suggesting 1/450 sec. The photo of the bird on the branch was taken at 1/500 sec and it's sharp enough. If you get more serious a tripod is in your future (a big heavy tripod).

In the Tv mode your camera will allow you to lock in the shutter speed you want to use. The camera's meter will then select and set the matching f/stop. You must still monitor this process. If for example you set a 1/400 sec shutter speed and the matching f/stop is then f/2.0 your camera won't be able to set that -- your lens can't open to f/2.0. Your camera will warn you in this case by flashing the f/stop value. You must then lower the shutter speed or raise the ISO.

Your photos: Altering the exposure would not have improved them. Here comes the bad news: What you see in your photos that you don't like and that you're calling underexposure is instead failure of the camera's image processor to get the tone and color of the photos correct. I fixed one of them for you.


I inset the histogram for the photo. If the photo were underexposed the histogram would have piled up against the left side of the graph. What's wrong with this histogram is that it's compressed. It should extend from the left corner to the right corner and it doesn't.

This is digital photography's dirty little secret: The camera image processors don't work very well. In your case the Canon Digic processor. I have the same processor in my Canon 5d and for $3,000.00 it's no better.

So your camera's not broken. This is what they do -- they all do it. Here on the forum you're going to encounter folks talking about RAW captures with their cameras. One reason Pros do that is because they want to keep the camera's image processor away from their photos.

Don't get discouraged; Adjusting your photo was trivially easy and you can learn to do it. You're already half way there since you saw the need for it. Here's a link to info about what I did:


Take Care,
i'll try to look for the those suggested books.

Joe, thanks for explaining the part about the processor. i think the camera gives me an option for RAW, but being unfamiliar with that, i steered clear. anyway, i'll read your link and try to apply what you've explained as well.

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