Hello, I'm new to this forum and, please, forgive me for my poor english.
I'm writing to ask some opinion about what I feel like a possible AF problem of my new canon 50D. I'm a little disappointed by AF performance of 50D (+300 f4l is usm + 1.4x) during last BIF session near to the sea last mid august. Ok, the light condition was not very good (sun "lateral" and not on my backside, so often the white herons's surface was half or totally in shadow in front of me) and probably worse than those one during my previous BIF session with Canon 40D (+100-400L) last april. Furthermore I understand that in august there's more umidity and air shake than during april and this could affect autofocus accuracy; but NOT as much as I experienced.
Then I did some test in house with a subject on the street 40-50 meters distant (subject as large as a human face) in perfect light or smaller subjects in my house 1-2 meters distant. Camera on tripod, 2 seconds MLU, remote wired control, IS off. What should be expected if (in both cases, big subject far away, small subject closer) you repeatedly half press the remote wired button ? the first time the camera focuses, and the subsequent times the focus ring remains stuck in the previous position. This is not the case unfortunately. There is definitely a focus random fluctuaction that has anything to do with micro af adjustment, because it is in fact RANDOM.
Then I get 50% of perfectly focused subjects after a series of shots with the 300mm f/4L is usm. With the 70-200 f/4L is usm I get 80% of perfectly focused shots. With Sigma 150 2.8 ex dg hsm, 30%. So the fluctuaction is worse with the sigma 150 2.8, a little better with 300mm f/4l, definitely better with 70-200 f4L is usm. Not tried of course with shorter focal lenght.
Any idea about this behaviour ? is the camera service the only thing to do ? Is it possible that I got a "very" (definitely very) bad 50D sample ?
thank youy very much for you help!
I'm writing to ask some opinion about what I feel like a possible AF problem of my new canon 50D. I'm a little disappointed by AF performance of 50D (+300 f4l is usm + 1.4x) during last BIF session near to the sea last mid august. Ok, the light condition was not very good (sun "lateral" and not on my backside, so often the white herons's surface was half or totally in shadow in front of me) and probably worse than those one during my previous BIF session with Canon 40D (+100-400L) last april. Furthermore I understand that in august there's more umidity and air shake than during april and this could affect autofocus accuracy; but NOT as much as I experienced.
Then I did some test in house with a subject on the street 40-50 meters distant (subject as large as a human face) in perfect light or smaller subjects in my house 1-2 meters distant. Camera on tripod, 2 seconds MLU, remote wired control, IS off. What should be expected if (in both cases, big subject far away, small subject closer) you repeatedly half press the remote wired button ? the first time the camera focuses, and the subsequent times the focus ring remains stuck in the previous position. This is not the case unfortunately. There is definitely a focus random fluctuaction that has anything to do with micro af adjustment, because it is in fact RANDOM.
Then I get 50% of perfectly focused subjects after a series of shots with the 300mm f/4L is usm. With the 70-200 f/4L is usm I get 80% of perfectly focused shots. With Sigma 150 2.8 ex dg hsm, 30%. So the fluctuaction is worse with the sigma 150 2.8, a little better with 300mm f/4l, definitely better with 70-200 f4L is usm. Not tried of course with shorter focal lenght.
Any idea about this behaviour ? is the camera service the only thing to do ? Is it possible that I got a "very" (definitely very) bad 50D sample ?
thank youy very much for you help!
