----- Original Message ----- From: Dr E D F Williams Subject: Re: Lens sharpness vs. camera shake
> Getting sharp images with long lenses is an exacting task, much more > difficult than meets the eye. Forgive the weak pun. I've been taking shots > of tree tops recently with a Sigma Apo 400/5.6. They are not particularly > sharp although I used the highest shutter speed I could. Its hard to decide > if the images are fuzzy because: the lens is not so good wide open, the > shutter and mirror vibrated the camera on the tripod, the lens is not so > good anyway, or the camera was not properly focussed. The pictures are on my > website if anyone wants to look at them and tell me what they think. They > are acceptable for the web, but 10 mbyte files on my monitor seem a little > soft. I usually focus by the 'rangefinder' method. I like your test subjects. My own experience with trying to get something critically sharp out of a longish lens was that metal tripods were a bad method of holding a camera. They "ring", and this vibration will pretty much ruin sharpness. Also, a fast shutter speed is almost counterproductive, as the shutter is still only giving you its flash sync speed, in reality, and this speed is often right in the range to show vibration. When I ran my tripod tests with the Super Program, I found that 1/8 second or longer showed the least vibration, having the camera vertical showed the most vibration, and that a heavy wood tripod was better than an equally heavy metal tripod. I have an untested theory that wrapping a bungee cord around all three legs of the tripod might settle the ringing down. William Robb
