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Thanks, Alex, for your "servo"-explanation. Again, the manual should at least inform about this quite fundamental "zoom OR focus"-limitation. (No reason for indignation, fans: I would have bought the A1 just the same. Like Alex says: The image quality in 25F is simply too good to resist). |
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Meanwhile I tested whether the AF focus pulsing also does occur while zooming manually (by zoom ring), as proposed by Sergio Barbosa. My first impression is that the pulsing is just the same.
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I tested it too, there is no focus pulsing. Only in badly lit, no contrast situations where an object is out of the center in the screen, and you zoom in, auto focus can't be easy found. This is understandable behavior, an object needs to stay in the middle, the two-way focus system tries one after one to focus, that is shifting in and out focus. It is very rare to happen, it is autofocus behavior. Sure you can manual focus in that situation.
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Hi all, first time poster.
Reading through this thread it occurred to me, is the focus-pulse-during-zoom thing largely a PAL issue? An earlier poster touched on this but nobody seemed to pick up on it. It just seemed to me that most (if not all) of the people who have complained of this problem seem to be from Europe and thus would be using the PAL version of the A1. Right? I haven't gone back through the entire thread systematically, but is it possible that the problem only exists on the PAL version, or is more pronounced on the PAL version? |
Ben, yes, judging from the reactions so far the pulsing may possibly be more pronounced on PAL units. Tom Roper posted a short 24p clip (NTSC unit) that also showed the pulsing, but I found it less pronounced than the pulsing I get on my PAL A1. But to become more certain, we would need more reports.
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The focus pulsing is probably due to the lower sampling rate of PAL shooting compared to NTSC shooting. When stepping down to 24F the sampling rate is very low, hence the pulsing appears on the NTSC model at that point.
FYI, I've shot some 24F under challenging lighting/focusing environments and gotten pretty severe pulsing, worse than Tom's sample. |
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It's fairly likely that the pulsing is caused by the motor switching back and forth between focus and zoom.
If this is the case it could be possible that in 24F/25F we're seeing a temporal artefact. For example, if this switching happens at 30 times a second (say) then you wouldn't see it in 30F or 60i. But you would see it in 24F/25F and to a lesser degree in 50i (although the interlace scanning would somewhat cancel out the effect). So it's possible it might be invisible to the vast majority of users who are filming 60i... |
Interesting thought, Alex.
Could anyone of the NTSC users shoot and upload a short native demo take in 60i (slow zooming to the long end, AF switched on)? |
I don't have upload capabilities here, otherwise I'd try to get a comparison 24F/60i clip up.
I can say that I actually tried to get the effect in 60i and wasn't able to. |
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So does the pulsing happen in NTSC at 30F?
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