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Old Feb 17, 2007, 6:03 AM   #1
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I've just attended a baptism where I needed to shoot in a low light situation. I used my Canon 400D with the 70-200L f4 IS, but what I've found is that pictures appeared much lighter/brighter on the camera's LCD than they did on screen when downloaded off the card into Picassa/Zoom Browser. Is this a common problem? Why the big difference? (It meant I thought I was more 'on target' with my camera settings than it turned out I actually was!)

I'm not sure how the IS works. Properties of the photos suggest aperture set at 4.0. If the IS makes the lens capable of 'four stops lower' shouldn't that be reflected? Am I not switching a button on the lens that I ought to be? What am I missing here?

I shot at ISO 1600 - obviously too high because my shots were all pretty grainy. What ISO setting ought I to have used for low light indoor shooting (church)?

With some similar shots, there was a significant difference between how light one appeared compared with the next one, yet there was no apparent difference in the 'specs' of the photo (ie: seemed to be the same focal length, aperture setting etc) Why might that be?
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Old Feb 17, 2007, 8:41 AM   #2
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IS doesn't help with what you're talking about.

When they say that IS enables you to shoot 'four stops lower' they mean that, in situations where you would normally have to shoot with a higher shutter speed to avoid camera-shake, IS will allow you to shoot with a slower shutter speed, a wider aperature, or a lower ISO setting (up to about 3 or 4 stops.)

It doesn't directly affect the exposure (or appear in the EXIF data.)

In situations where you wouldn't have worried about camera shake (i.e.: shooting from a tripod or bracing the camera against some fixed structure) IS doesn't give you anything extra. And it doesn't affect the automatic exposure system.

In low light (such as inside a church), you would normally have to shoot with a wide open lens, a slow shutter speed and a high ISO setting, in order to capture as much light as possible. IS will stabilize the image such that if you wanted to speed up the shutter speed to avoid camera shake (from being jostled by the crowd, from your own unsteadyness, from seismic tremors, whatever), you could instead use a lower ISO setting, or close down the aperature in order to get a deeper Depth of Field.

If you shot this baptism at ISO 1600 and f/4, then the shutter speed must have been pretty fast to give you dark images. (I'm guessing you were after 'available light' shots, so you didn't use the flash for 'fill-in') You may have a problem with your camera's auto-exposure settings, or with the AE system itself.

For indoor shots (especially in churches, which are notoriously dimly lit), you should be able to use ISO 1600 (I'm surprised that you got a lot of noise in your shots.)and a wide open lens. The only other factor is what the AE might have told the shutter to do.

I don't think the problem is with your IS; I think the problem is with your AE.
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Old Feb 17, 2007, 8:21 PM   #3
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Ange wrote:

With some similar shots, there was a significant difference between how light one appeared compared with the next one, yet there was no apparent difference in the 'specs' of the photo (ie: seemed to be the same focal length, aperture setting etc) Why might that be?
Tcav answered the rest pretty well so I'll chime in on this part. The differences are likely do to metering and what subjects are in the meter zone at the time the photo is taken. For instance, the white of the baby's outfit will throw the metering off a bit - it will likely underexpose to try and get the white a neutral grey - about 2/3 to a full stop underexposed.

What you need to do is learn how to read the histogram. Use that as your guide to a proper exposure rather than the image display. You would likely find that image that looked well exposed actually had a histogram shifted to the left. As I shoot a lot of sports, much of my shooting is in low light. And the issue you described regarding an image that looks fine on the camera lcd but is actually underexposed is fairly common. That's where the histogram comes in - it doesn't lie as much as the image review does.

As for grain - you get more digital noise when an image is underexposed. You will always have some noise at ISO 1600 but if the shot is exposed properly the noise is easily cleaned up with noise removal software (noiseware, neatimage, noise ninja). So, fix your exposure problem by using exposure compensation or shooting in manual mode and you'lll improve the noise problem. Then get a copy of one of the above pieces of software and you can completely remove the noise.

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Old Feb 18, 2007, 3:48 AM   #4
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Did you shoot these photos RAW? If so, they probably came out better than you think. I haven't used Zoom Browser, but I know that when I view my RAW images in Picasa it does some auto adjustments that sometimes look very different from the LCD preview, and it has a tendency to look extremely noisy at higher ISO levels. Once the image is imported into Photoshop though, with some proper exposure adjustments and a moderate amount of noise reduction, it looks about 20 times better.
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Old Mar 7, 2007, 12:52 AM   #5
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To summarize, or just make sure the main point is clear:
"Four stops" applies to the shutter speed. So at 120mm, instead 1/120 shutter you could (in theory) use a 1/8 shutter.

But that won't stop blur from subject motion (even if the IS is that good). Still, there are alot of still moments in a church where you ought to be able to get away with 1/30 or mabe even 1/15 with that lens.

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Old Apr 2, 2007, 10:44 PM   #6
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50mm F:1.4 is the answer...all the rest is rationalization for using the wrong lens for the conditions.
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Old Apr 4, 2007, 5:18 PM   #7
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Here is a sample photo taken with my Canon XT fitted with the Sigma 30mm F 1.4 lens at ISO 800 no flash and handheld.

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Old Apr 13, 2007, 11:22 AM   #8
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Agree. Simple solutions are the best.
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