Question from a reader
I saw that you wrote an article on zoom lenses last month and wanted to see if might have an explanation for an issue I seem to be having with mine. I have a Canon 40D and bought the 70-200mm L-series f/2.8 lens earlier this year to help me with weddings. It does not have the image stabilization feature on it, but the reviews I read were really good for either lens. The issue I seem to have is getting tack-sharp images, specifically in low light of slow moving subjects.
I auto spot focus on each shot making sure the focus sensor is on the face of the subject I’m shooting, but when in low light without a flash, it’s as though the camera doesn’t have enough information/light to make the image sharp. I put ISO at 650 or 500 (higher than that makes it pretty grainy on my 40D) and even then it’s a little grainy. I’ve also read some articles that say there is a zone in lenses that creates the most sharp images – a middle f-stop and middle/higher shutter speed (around 1/160 or 1/200 or so). Since my exposure won’t come out with really high settings for these specific instances, I try to keep my f-stop around 3.2, maybe 3.5, but know that 2.8 affects my depth of field and that it doesn’t seem as crisp at that aperture. I’d love to have it at f/8.0, but there’s no way the image would have enough light at that aperture. I also try to keep my shutter speed around 1/80 of a second or 1/100.
I’ve even tried all of this on a tripod and still have the same result. Some photographers I’ve talked to say they are able to take images from the back of a church with no flash and then zoom in/crop later and get great detail. Am I missing something? I am beginning to wonder if it’s my camera body…I can’t image the lens being faulty seeing how much it was and that it’s supposed to be the L-series. I’d like to try the lens on another camera body, but haven’t had the opportunity to do that just yet.
So anyway, any insight you could provide on this issue would be amazing, as I’ve tried to do a lot of research and am just getting frustrated that I can’t get the images I want, even though I see the shot through my lens. Thanks in advance for any help!