stanj wrote:
Ok, I did the test as you specified. I too took a blue water bottle. I shot 1.4, 2.0, 2.8, 4.0 in this order, first AF then MF, each time mis-focusing the lens in between shots. My results are about the same as yours - the AF pictures aren't as sharp as the MF ones. In my case I suspect it's because my outer AF sensors aren't "aligned" with the center one - when using the center AF point the images were perfectly in focus.
I'll get the pictures to you tomorrow offline, don't have the bandwidth today.
Thanks Stan
Does the "bad" performance of outer AF points appears to be random and unrepeatable (sometimes good focus, sometimes worse)? Or do you get consistently "bad" performance on certain outer AF points?
I'd say the focus is consistently off, which would further strengthen my belief that the center and outer points are simply out of sync. I need to send it in for calibration, if I only find the right time to be without it for 1-2 weeks...
stanj wrote:
I'd say the focus is consistently off, which would further strengthen my belief that the center and outer points are simply out of sync. I need to send it in for calibration, if I only find the right time to be without it for 1-2 weeks...
I understand... So basically you would see the same "bad" outer AF point performance with other lenses too?
Daan B wrote:
I understand... So basically you would see the same "bad" outer AF point performance with other lenses too?
Yes. Today I tried only the 35L in controlled settings, but my gut feeling - after 40k clicks with the 1Ds3 - is that the behavior is the same; I get way more off shots with the outer AF points. The camera went in for service once before, and somehow I assumed that they would run AF calibration without saying (as they used to with service on my 1Ds and 1Ds2), but they didn't, so it will be a separate trip. Until then, safety in numbers
stanj wrote:
Yes. Today I tried only the 35L in controlled settings, but my gut feeling - after 40k clicks with the 1Ds3 - is that the behavior is the same; I get way more off shots with the outer AF points. The camera went in for service once before, and somehow I assumed that they would run AF calibration without saying (as they used to with service on my 1Ds and 1Ds2), but they didn't, so it will be a separate trip. Until then, safety in numbers
I don't know if my AF problems are the same as yours, because in my case AF problems are erratic, random and unrepeatable on all 19 AF points with all my lenses (although the 70-200 gives the least problems). I had my cam checked twice and let Canon Service calibrate all the 45 AF points. Which were not exactly off in the first place. AF problems didn't go away after that. The problems became less though (according to the tech because he adjusted the contrast levels as part of the calibration routine). All I am saying is that calibration may be the answer, but it could also be that effects are going to be minimal.
Call it accuracy or precision, but calibration won't help because the focus can change slightly from one shot to the next. But f1.4 at 21 megapixel is a major stress test. I doubt any current autofocus system can satisfy those demands. Canon needs a better AF technology if it wants to continue fighting a megapixel war.
brainiac wrote:
Call it accuracy or precision, but calibration won't help because the focus can change slightly from one shot to the next. But f1.4 at 21 megapixel is a major stress test. I doubt any current autofocus system can satisfy those demands. Canon needs a better AF technology if it wants to continue fighting a megapixel war.
Daan B wrote:
I don't know if my AF problems are the same as yours, because in my case AF problems are erratic, random and unrepeatable on all 19 AF points with all my lenses (although the 70-200 gives the least problems). I had my cam checked twice and let Canon Service calibrate all the 45 AF points. Which were not exactly off in the first place. AF problems didn't go away after that. The problems became less though (according to the tech because he adjusted the contrast levels as part of the calibration routine). All I am saying is that calibration may be the answer, but it could also be that effects are going to be minimal. ...Show more →
I insist with the focusing screen, because when I replaced the original with the ec-D on a 1DsII I saw the same "erratic" AF with any lens. a la 10D to be exact
with the original screen everything was back to normal. It may be a defective screen (of course), but the camera was the same and so the lenses and the AF was jumping within shots (of the same target)
a quick check on the screen (take it out and re-position making sure that it "clicks" firmly and correctly in the holder .. maybe?
markle wrote:
I insist with the focusing screen, because when I replaced the original with the ec-D on a 1DsII I saw the same "erratic" AF with any lens. a la 10D to be exact
with the original screen everything was back to normal. It may be a defective screen (of course), but the camera was the same and so the lenses and the AF was jumping within shots (of the same target)
a quick check on the screen (take it out and re-position making sure that it "clicks" firmly and correctly in the holder .. maybe?
.
I have replaced the original focus screen with an EC-D screen... In both cases I still had the same AF issues. It could be that both are defect, but that would be something, right?
