View Full Version : Focus issue solved, faulty camera now replaced


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Michael Mann
January 4th, 2007, 04:58 AM
Michael, I've just checked and the Z1 and FX1 can be zoomed AND focused at the same time, both using the zoom ring and focus ring or the zoom lever and focus ring.

Thank you, Alex, for checking this. I sort of remembered it that way, but was not sure.

How come the FX1 can do this and the A1 don't? The FX1 has a "servo" (what is this, by the way?) for zoom and focus as well, right?

Soeren Mueller
January 4th, 2007, 05:00 AM
What a bummer... the full manual zoom is really a great thing.. even if you don't do crash zooms all the time ;) it simply "feels" much better because you just have more manual control... guess this is a case of try before you buy then... let's see if the servo zoom is sufficient for my needs.
Jeez when will they finally come out with a camcorder in that price range where you can switch off all that damn servos ;o) .. i hate all this "automagic" stuff...

Alex Leith
January 4th, 2007, 05:21 AM
Thank you, Alex, for checking this. I sort of remembered it that way, but was not sure.

How come the FX1 can do this and the A1 don't? The FX1 has a "servo" (what is this, by the way?) for zoom and focus as well, right?

I suspect the FX1 / Z1 has two servos, one for focus and one for zoom. A servo is basically a variable speed motor that you can control using some sort of a "proportional" control surface - like a lens ring.

As I understand it, Canon lenses use a single motor for both zoom and focus, probably with some kind of mechanical gearing that (invisibly) switches between the two mechanisms.

Although autofocus continues to work during zooms on the A1 (with the unfortunate addition of pulsing artefacts in 24/25/30F modes) the focus mechanism appears to be disengaged during zooms in manual focus.

The lens control on the FX1 / Z1 was one of the nicest I've ever come across on handheld prosumer cameras. The lens rings were setup just right (for me) and it did pretty much whatever I asked of it, with very smooth professional looking results.

I adore the extra resolution of the A1's image (I was shooting cineframe with the FX1 which is very soft), I love the image controls, and I love the extra range on the zoom... but I'm not smitten with the "feel" of the lens controls. There have been occasions where I'd like to rack focus and zoom at the same time (background landscape to foreground presenter for example).

It seems like you can't quite have it all...

Raymond Toussaint
January 4th, 2007, 05:42 AM
Crash zooming is manual lenses only (I'm old school). No servo lens is doing that really. Indeed Alex, you can't have it all. If you mix all the sub $10.000 cams together and take the goodies, you are close, but it's never going to happen. Live with the quirks and the strong parts.

For the most you can live with it by changing the way you shoot or work, 'workarounds'. You can continue what is not there -the empty glass- or what is there -a half bottle- and make the best out of it. I bought this cam, it gives me an incredible lot for the money, it is by far the best buy I can get.

Sergio Barbosa
January 4th, 2007, 06:05 AM
Regarding the pulsing issues... Has anyone tried zooming manually with autofocus on... Does that pulsing still occurr?
If it's a servo lens, and works like my sony dsr 250's, the zoom should be smooth enough.

Philip Williams
January 4th, 2007, 06:11 AM
<snip> Has anyone tried zooming manually with autofocus on... <snip>

Uh.. well, you don't really zoom "manually". Its always a servo controlled zoom, regardless of if you use the rocker or the lens ring. So if you zoom (using any method) with autofocus on, the pulsing can occur.

Michael Mann
January 4th, 2007, 01:39 PM
So if you zoom (using any method) with autofocus on, the pulsing can occur.
Sounds reasonable. Anyway - has anyone TESTED whether the pulsing really occurs during "manual" zooms? Thanks, Sergio, for your proposal. I will test and report.

There have been occasions where I'd like to rack focus and zoom at the same time (background landscape to foreground presenter for example).
Yes, that goes for me too. And there is no possible workaround - either zoom or focus. (Not true: We could always focus in camera and "zoom" in post - I'm joking).
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).

Raymond Toussaint
January 4th, 2007, 06:34 PM
1. You can manually focus and zoom together.
1a.You can manually focus and zoom together and use Push Focus button on subject.

/snip

Normally always set everything on manual and use the push focus button if needed. Or if you want to use AF, not in the same time during the zoom, set cam to AF for easy focussing on moving object.

I need to come back on my early post on manually focus/zoom behavior, camera is back in the house and todays testing find out that you can not zoom and focus together. You can move the rings but one action (zoom) has priority over the other (focus). You can zoom in manually and push AF button but actually focussing is on the moment the zoom acton is finished.

Michael Mann
January 7th, 2007, 11:13 AM
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.

Raymond Toussaint
January 7th, 2007, 06:56 PM
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.

Ben Hayflick
January 8th, 2007, 01:32 PM
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?

Michael Mann
January 8th, 2007, 01:54 PM
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.

Philip Williams
January 8th, 2007, 02:11 PM
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.

Michael Mann
January 8th, 2007, 02:22 PM
I've shot some 24F under challenging lighting/focusing environments and gotten pretty severe pulsing, worse than Tom's sample.
Philipp, if possible - could you upload a short sample of yours?

Alex Leith
January 9th, 2007, 04:15 AM
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...

Michael Mann
January 9th, 2007, 04:56 AM
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)?

Philip Williams
January 9th, 2007, 06:42 AM
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.

Michael Mann
January 9th, 2007, 06:53 AM
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.
Thanks, Philip. That is interesting to know even so.

Ben Hayflick
January 9th, 2007, 08:58 AM
So does the pulsing happen in NTSC at 30F?

Michael Mann
January 10th, 2007, 03:40 AM
So does the pulsing happen in NTSC at 30F?
We simply don't know yet in general, Ben. Therefore we would need more reports from NTSC users.

Michael Mann
March 26th, 2008, 03:19 AM
I just tested Canons HV30: It shows exactly the same focus pulsing during zooms when in AF mode.

This issue is obviously not only a A1 related problem.