A large percentage of my photos of my 2 year old appear to be blurred. I know one of the problems is that she will not sit still for a second, but I am using a fast shutter speed. Could IS be causing some of the blur?
I am using a Canon 50D with 17-55mm f2.8 lens. Aperture set at f2.8 and shutter speed at 1/50. Keeping the ISO down to 200. I must add that most of my photos are taken indoors and I hate using the inbuilt flash!
@Dan, that's a good question. I suspect that most of us have a problem with blurry images more often that we would like.
It's unlikely that Image Stabilisation is causing this problem. I have certainly never had this problem myself. However, IS reduces camera shake - that probably isn't your problem.
The rule of thumb often touted is that shutter speed should be faster than 1/focal length in order to avoid camera shake. However, this may not be fast enough for a fast-moving child.
I suggest that a speed of 1/250 or more may be necessary.
It could be that autofocus is in the wrong mode. Most DSLRs have several autofocus modes. One of these will be "single shot", where the camera focuses when you press the button, and keeps that focus until the photo has been captured. This mode will often result in a blurry subject if the subject is moving towards / away from the camera. Instead, consider a mode which is trying to track the subject. Depending on your camera, this may be called "AI Focus" or "Continuous" mode. (others are welcome to chip in / edit this answer to get the right terms used by different manufactures).
If you have enough light, you could try a using smaller aperture to give you more depth of field. Obviously, this may slow your shutter speed, so there may be a trade-off to consider here.
Finally, if you are using a compact camera, or a DSLR in an auto mode, check which mode it is in. For children, sports or action mode is often best. That should tell the camera to automatically use the highest shutter speed it can, and to prioritise freezing the action.
Hope this helps.
It's unlikely to be IS. If it is, then IS is seriously broken. It's generally safe to leave it on all the time except when you are using a (very firm) tripod. That said, with a moving child from close range, IS really isn't likely to have much of an effect.
What it could be, from most to least likely:
Subject moving in and out of focus.
By the time your autofocus has locked on to a fast moving subject and you click the shutter, she could be out of focus again. You could try selecting the C-AF mode (Continuous Autofocus) but then you may find that your camera spends valuable time "hunting" focus (though a good DSLR will be better at this). Another approach may be to make sure you can stop down the aperture a bit to increase the depth of field (you may need to be in brighter light eg daylight for this). Then it'll be a bit more forgiving if she moves out of the focal plane a little. Another is to move the camera with her, in such a way as to keep the camera a constant distance away from her while focusing and taking the picture.
It's also possible that the autofocus area is letting you down; rather than let the camera guess what to focus on I tend to use a single autofocus area and point that directly at the subject I want in focus, though you can also use multiple areas and let the camera choose which one to focus on. If using the former, it's very important that you line up the active focus area on your LCD/viewfinder with whatever you're focusing on. Most important is to become used to autofocusing so it becomes second nature, and you can point, autofocus, then shoot nice and quickly.
Motion blur (subject movement).
If the blur is motion blur, it indicates that your shutter speed is too slow for the amount your subject is moving. Remember that IS does nothing to combat motion blur, only the shake of your own hands holding the camera. To really freeze human motion, you'd ideally want 1/500 of a second, however at 1/250 or 1/125 you'll probably find a good proportion of your shots are still nice and sharp. But once you get to 1/60, 1/30 etc it's too slow for human beings moving around. Those speeds are fine for landscapes but not for people unless they're posing still.
Note that if you're indoors under artificial light, you will be hard pressed to be able to use shutter speeds that fast, and unfortunately you'll need to move into the daylight, use flash, boost the ISO level up very high, or buy a fast prime lens for your camera. You could try and see what your camera does if you put it into shutter priority mode at 1/250 - if it complains it's too dark boost the ISO more. See what happens.
Other.
Check that the lens is clean and its zoom mechanism is not wobbly or loose. Make sure you have a firm grip on the camera. Etc
On Canon DSLR lenses at least, the internal stabilization mechanism takes a half-second or so to whirr up to speed before it actually stabilizes. If you just jam down the shutter button without giving the IS this time, it can easily make the photo more blurry rather than less. I'd try switching it off - it will not do one bit of good anyway on a moving subject at shorter focal lengths.
As far as i know IS is only useful when shooting still subjects. It can compensate your movements, but not the movements of the subject.
I'm not sure it can cause blurring on its own, but you should be easily able to switch it off and check the results.
I have both the EOS 50D and the 17-55mm F/2.8 as my primary lens. I always have IS turned on, however it seems you need to lighten up on the ISO.
The 50D will produce a pretty decent image even at ISO 1600 (the limit for me).
Even at ISO 800 your shutter speed is now a very usable 1/200th.
Don't be afraid to use a higher ISO. Alternatively, you could look at getting the cheap Canon 270EX flash and use it pointed at the ceiling to light up the scene quite nicely.
This example is at ISO 1600.
