@AustinVinar, IS can be helpful for stabilizing the camera side of motion blur, but it can’t compensate for subject motion blur. That’s where more light (larger aperture) is more useful than IS. If the subject is moving, and you’re shooting at 1/40, you could take a dozen pictures and not one of them be sharp. However, if you have a wide enough aperture that you can move the shutter speed up to 1/100 or 1/125, then you’ve got a much better chance to get a blur-free photo.
