Saturday, March 8, 2008
Long focal length lenses
I was hoping to use an example of the sort of problems encountered with lenses of 200mm or equivalent, it seems that I deleted it so here is a good one(well OK). To cut a long story short. I borrowed a Canon 350D camera with a Tamron zoom lens that I was using at about 150mm focal length equivalent - 38mm actual . I was using a pretty solid tripod and available light. I had spent hours the previous day trying desperately to get a sharp image. The camera was on a Manfrotto tripod - one heavy duty enough for a 4x5 camera. The lens seemed to become sharp at f16 so that is what this was taken at. To complete the job I set the camera to "Mirror-up" and used the remote control release. Well the shots came out sharp and the client was pleased - and he paid me. However, if I had not have spent a few hours experimenting then it would have been a disaster. When shooting for best quality I try and use the 100 ISO setting as that produces the least "noise" in the picture. The Canon is still pretty good at higher settings but if you want to avoid speckly shadow areas then stick with the slower ISO setting.
As a result of this I was using a shutter speed of 1/2 sec which is far too long for hand holding. In this picture of a full size dining room chair you can see how sharp it is (at least you can in the original). If you are taking pictures in extreme circumstances, without a tripod, try and find something solid to lean the camera on and also shoot several shots at a time. Usually at least one will be sharp. If you are shooting moving objects- and you need to pan the camera with the movement-keep your finger on the expose button. Digital film is cheap opportunities are rare.