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11-19-2009, 03:57 PM   #1
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Exposure.

I was out shooting some photos of waves last night with the sunlight fading fast. Checking the image (and histogram) on the LCD showed that the images were somewhat underexposed. As a result, I cranked open the aperture and reduced the shutter speed to levels which caused camera shake to be quite noticable. (Wind was 40mph).

When I got home I imported one of the DNG files and was surprised how well exposed it was given the conditions. (I posted it in the pictures thread).

The problem I see here is that I rely on the image and histogram that are telling me to increase exposure through whatever means which makes for shaky handheld photos. I find it misleading when the exposure is fine in the RAW files.

Any tips?
Thanks.

11-19-2009, 04:19 PM   #2
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Not sure this is really PP related, but I'll wait to see where the discussion goes before moving thread.

Anyhow, I'd have to see the shots in order to say, but I'd guess the problem was in thinking the histogram was telling it was underexposed in the first place. If that's the exposure the camera originally suggested, you might as well assume it was for a reason. People tend to expect pictures with perfectly centered histograms, but that's not necessarily "correct". ISO standards call for the histogram to be half a stop or so *left* of center, and that's assuming metering a solid colored object. In the real world, often there's a spike right at the right edge that we don't see at first (sometimes it's only easily visible when we ask to see the individual color channel histograms, and sometimes not clearly even then) that we aren;t taking into consideration as much as we should. And of cours,e even in fading daylight, the LCD can't compete with the level of the sun or the sky, and we'll often tend to think our pictures are too dark.

Anyhow, it's for the basic reason you mention that I started using M mode, at first in low light but eventually all the time - I don't want the camera suggesting two slow a shutter speed just because it thinks the picture will be underexposed. I'd rather set the shutter speed I know I want, and live with possible underexposure, knowing full well that while I can brighten it in PP, as often as not, it won't be necessary.
11-19-2009, 04:28 PM   #3
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QuoteOriginally posted by Marc Sabatella Quote
Not sure this is really PP related, but I'll wait to see where the discussion goes before moving thread.

Anyhow, I'd have to see the shots in order to say, but I'd guess the problem was in thinking the histogram was telling it was underexposed in the first place. If that's the exposure the camera originally suggested, you might as well assume it was for a reason. People tend to expect pictures with perfectly centered histograms, but that's not necessarily "correct". ISO standards call for the histogram to be half a stop or so *left* of center, and that's assuming metering a solid colored object. In the real world, often there's a spike right at the right edge that we don't see at first (sometimes it's only easily visible when we ask to see the individual color channel histograms, and sometimes not clearly even then) that we aren;t taking into consideration as much as we should. And of cours,e even in fading daylight, the LCD can't compete with the level of the sun or the sky, and we'll often tend to think our pictures are too dark.

Anyhow, it's for the basic reason you mention that I started using M mode, at first in low light but eventually all the time - I don't want the camera suggesting two slow a shutter speed just because it thinks the picture will be underexposed. I'd rather set the shutter speed I know I want, and live with possible underexposure, knowing full well that while I can brighten it in PP, as often as not, it won't be necessary.
Thanks. Move the thread if you'd like, I wasn't sure if this was PP related since I was fiddling with the RAW images

As for the camera "suggesting" a shutter speed, I don't understand this. If I am in full manual mode, where is the camera suggesting a different shutter speed? BTW, I was in TAv mode for these photos.
11-19-2009, 04:31 PM   #4
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It's usually assumed that you are using one of the auto modes which would adjust other variables for you. If you were in TAv mode, then ISO is automatically adjusted for you.
In any case, once you've metered a scene in M mode, and you make your compensatory adjustments, then you've relied on your own judgement to get the exposure right.

Discrepancies between the histogrom and the results on screen are usually because of the auto settings on the software automatically brightening up an under-exposed image as a suggestion to your PP work.

11-19-2009, 09:04 PM   #5
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QuoteOriginally posted by sebberry Quote
As for the camera "suggesting" a shutter speed, I don't understand this. If I am in full manual mode, where is the camera suggesting a different shutter speed? BTW, I was in TAv mode for these photos.
Well, you didn't tell us what mode you are in. But even in M or TAv modes, the camera is more than happy to suggest an exposure when you hit the Green button. So I just assumed your initial exposure was camera-suggested.

I move this to the beginner forum. That's probably not completely appropriate either, but it's probably a question of general interest to beginners, so I hope you don't mind.
11-20-2009, 08:09 AM   #6
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When I'm confronted with a low-light situation and camera shake is a real danger, I use a trick I read about. It was in a book (I forget the title) by a pro photographer who used Canon equipment. The book was all about the advantages of using RAW mode.

I deliberately underexpose by up to two stops. This lets me keep the shutter speed high enough to reduce the risk of camera movement. Even with the SR on, there is a limit to how slow you can go.

Because I shoot in RAW (I use PEF, but DNG would work just as well), I can bring the exposure back up to where it should be in post processing. If I shot in JPEG, it is much less likely that I would be able to get a decent image. With RAW, the image is more than just acceptable. I suppose that a devoted pixel-peeper could tell the difference between such an image and one made on a tripod and exposed "correctly" in the camera, but I can't. Photoshop or other programs can correct for poor exposure, but there is almost nothing that can be done in PP to correct camera movement.
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