I’ve been having trouble with my Sigma 70-300mm lens. I keep getting photos like this out of it.
Not very sharp at all. I was begining to think that I’d never be able to use the darn thing without a tripod, which would be very sad indeed. Then my photo-geeking neighbor, DavidB, told me somehting I’d read somewhere and then forgotten. He said “Use the middle F-stop.” For those of you unfamiliar with cameras and lenses, here’s a quick bit: lenses have blades or plates, which open and close to let light in. Each setting of these blades is called a ‘stop’ or an ‘f-stop’. The 70-300mm lens stops from F/4 to F/29, making the middle stop of this lens F/11 or so. My 50mm Macro goes from F/2.8 to F/44, making it’s middle stop somewhere around F/22. It’s different for every lens. So, I decided to do a bit of an experiment. Is the 50mm lens sharper than the 300mm lens, even when the photo is enlarged? If I could get away without taking the big 300mm to Arizona, I’d be happy.
The 300mm is on the left, the 50mm enlarged is on the right. Pretty darn sharp, even when compared side-by-side. These shots are from a tripod mounted camera, which means that there’s no shaky hands making the camera’s pictures fuzzy. If I wanted to drag a tripod around the whole vacation, this would be great. Me, I’d rather hold the camera with my hands and turn myself rather than picking up some contraption to follow a hummingbird. Since I have notoriously shaky hands, I needed to know if I could get a usable photo out of the 300mm at all, or if I should just hope for the best with the 50mm.
This is a hand-held shot of a pair of doves I just took. The doves were about 20 feet away from me. Nice and harp! Yay! The middle stop works quite well for hand-held shots in bright sun. Not so well for shady areas though. But, I think I can safely take it with us and get a few good shots out of it, at least at the zoos and feeders. Wheee!
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3 Comments
If you leave the lens and tripod behind, doesn't that just guarantee you'll find a shot which requires them?
LOL. Of course it does. I refuse to take a large tripod, but I do have a smaller Bogen Table/Wall/Tree tripod, which should come in handy if there's a table or wall or tree nearby. It's only 8 inches long, so it's a breeze to carry.
Several thoughts:
Enlarging a 50mm pic will be just the same as the "digital zoom" built into many cameras. All it does is blow up the existing pixels. Not recommended. If the blur is from lens motion (probably is, without a tripod) you'll get exactly the same blur by zooming in or by blowing up the 50mm pic.
Use a shutter speed at least as fast as the lens zoom setting: If the lens is zoomed to 300mm, use at least 1/300 second (preferably 1/500 or faster) when working without a tripod. Otherwise it WILL blur unless you've been off the caffeine for a long time.
When hand-holding the lens: focus, inhale deeply, exhale halfway, hold breath, then squeeze the shutter. It works.
Most lenses are sharpest a couple of stops down from their smallest f/stop, but the difference isn't usually a big one. Better to go with shutter-priority (Tv mode on a Canon) and set the speed fast enough to avoid shaking.
Great pictures - keep 'em coming!
Bob