kewlcanon wrote:
@gotak the 2nd picture, you're shooting 1/200s and f/4.
The one shot tests were all in f2.8. Where did you get f4 from? The servo AF set was in f4 because I needed bit more DOF. Would have gone higher but I was at at iso 3200 already.
gotak wrote:
The one shot tests were all in f2.8. Where did you get f4 from? The servo AF set was in f4 because I needed bit more DOF. Would have gone higher but I was at at iso 3200 already.
Brainiac, are these failures you're seeing just with the 24f1.4 ? I seem to recall threads about focus problems with very fast glass.
I've had two 7D's, the first one was defective(AF), so I waited 4-5 months before getting another, and the one I have now is light years better. I find for tracking birds moving about from perch to perch that it works very well and image sharpness is excellent, however I have noticed situations where it struggles. One is in high contrast light such as clear sky with the sun overhead. The focus will appear to be correct in the viewfinder, but upon image inspection , the image is significantly soft. No amount of "pumping" the AF solves this, it just struggles in that situation. What I've done as a workaround is to close down a stop or more, which I assume solves the problem by increasing the DOF. Pretty much any other lighting condition is fine.
The second situation is where the background is complex and contrasty. The focus will jump to the BG even if the sensor spot is on the subject with only 20% "seeing" the BG. It makes me suspect that the actual AF sensor area is quite a bit larger than the viewfinder AF squares. Switching to the point AF mode helps, but it will still do it in the right situation.
One is in high contrast light such as clear sky with the sun overhead. The focus will appear to be correct in the viewfinder, but upon image inspection , the image is significantly soft. No amount of "pumping" the AF solves this, it just struggles in that situation.
The second situation is where the background is complex and contrasty. The focus will jump to the BG even if the sensor spot is on the subject with only 20% "seeing" the BG. It makes me suspect that the actual AF sensor area is quite a bit larger than the viewfinder AF squares. Switching to the point AF mode helps
+1 on both of these observations. I've experienced exactly the same behavior (using the 400/5.6). Not a deal killer, but annoying nonetheless.
z