View Full Version : Focus issue solved, faulty camera now replaced
Alex Leith December 7th, 2006, 03:21 PM Admin note, update from Dec. 18th: Alex took our advice and sent his camcorder to Canon service, where it was found to be faulty and has been replaced. See the post from Alex at the end of this thread. The issue is now considered as resolved. Thanks to all who participated -- CH
Please, please, please I need your help. I've sent my XH-A1 back to the dealers because of problems with the focus (which can be seen at www.19media.com/xha1).
However, they had a quick play and say the performance is normal. But I'm convinced it's not right. If any XHA1 owners could try the following tests (preferably in 24F or 25F) and report back, it would really help me to convince them to send it back to Canon for repair...
1. With IAF on, zoom to the long end of the lens and fill most of the screen with a nearfield object so the object is in focus, and the background is out of focus. On the slowest zoom setting zoom out for a few seconds and then back in again. Do you see any sort of pulsing in the out-of-focus part of the image?
2. With AF off, zoom in and point the camera at something that should be easy to focus on. Manually defocus and then press the IAF button. Try this a few times.
2a. How long (in seconds) does it take your camera to focus?
2b. Does your camera ever rack focus in the wrong direction?
2c. Do you get consistent results each time you press the IAF button?
3. With IAF on zoom into an object like a poster on a wall. Let the camera focus. On maximum speed, zoom out and zoom back in again straight away. Has the camera lost focus?
Thank you, thank you, thank you. I would be so greatful for your reports. And I'll buy any of you a beer if you ever find yourself in Northampton, UK (though frankly you're probably lost or on the way somewhere else if you do find yourself here!)
Dave Lammey December 7th, 2006, 06:23 PM I don't have the A1, but I do have the HV10, which also has the Instant AF and sometimes exhibits similar behavior when aiming at something in the foreground that is just left or right of the middle; because the IAF is so fast, it looks like the spastic pulsing you described. Have you tried turning off the instant AF and using normal AF?
Alex Leith December 7th, 2006, 06:29 PM Yes, the behaviour is the same both with IAF and AF. And I've tried it on a shot where three quarters of the shot was in focus foreground, and just the very left edge was out of focus, and it exhibited the same behaviour there too.
Also the pulsing only happens while zooming.
I'm hoping that someone else with an A1 can let me know how their cameras respond to the tests I've suggested so that I can say to my dealer "these aren't normal - other people's cameras aren't behaving like this..."
Tony Tremble December 7th, 2006, 07:30 PM A much better clip to show the problem. Apologies for doubting you.
The XL-H1 couldn't focus while zooming so I am wondering if the XH-A1 is limited in the same way and what you are seeing is the camera switching between focus and zoom very quickly causing the shimmering effect. The shimmering has a regular looking "beat" to it.
Can you manually focus and zoom at the same time on these XH-A1s?
Focus being lost on zooming doesn't sound good to me. If you've zoomed in made critical focus, zoomed out to record the zoom in you would expect focus to be there. This sounds like a fault.
There haven't been any other reports like yours and a good many people seem to be very happy with their A1s. Sounds like a trip back to the dealer.
All the best
TT
Khoi Pham December 7th, 2006, 08:04 PM I see it too with the A1 but I mostly use manual focus so it doesn't bother me that much, you can't rely on auto focus with any brand, I do have Sony Z1 and it does not hunt like A1 but I don't really use auto on it either.
Andy Wason December 7th, 2006, 08:25 PM I see it too with the A1 but I mostly use manual focus so it doesn't bother me that much, you can't rely on auto focus with any brand, I do have Sony Z1 and it does not hunt like A1 but I don't really use auto on it either.
I agree wiyth Khoi. AF is a crutch we depend on, but it's less than perfect. I had a heck of a time getting AF to work in low ligh on my A1.
btw you couldn't zoom and focus at the same time on the GL1 and 2 , don't know about the XL and XH series.
Apparently you can do this with the sony PD 150.170 etc.
Andy
Philip Williams December 7th, 2006, 08:33 PM You know, I think I saw something similar to this with my A1 while shooting some taller buildings at night. Most of the frame was pretty dark and seemed OK, but the lights on the building were sort of "pulsing" just slightly in and out of focus. I'll have to review that footage over the weekend to confirm.
Greg Boston December 7th, 2006, 08:50 PM The XL and GL series cameras can't zoom and focus at the same time because they share a single servo motor. Like Tony mentioned, if you zoom in and get critical focus, it should hold focus all the way back out and in so you shouldn't need focus while you do the zoom. If it doesn't hold focus, it's a back focus issue which I believe has an auto correction available via the menus. Also known as flange back adjustment.
-gb-
Tony Tremble December 8th, 2006, 06:43 AM I feel the most effective way to use autofocus on any of these compact cameras is in a semi automatic mode. By that I mean making use of the one push AF control. Zoom, make focus with the one push AF, zoom out and re-frame. I have found it a much quicker approach than to fight the, generally, spongy controls on compact cameras. With a should mount camera I could usually focus and zoom at the same time as bother hands were operating the lens. Not so easy to do with a compact camera when one hand is supporting its weight.
I cannot stress how important it is even with the most intelligent super duper autofocus system in the world to zoom, focus and reframe subjects. Sooner or later the autofocus will guess wrong and you'll lose an important shot. Very easy to do with such small VFs and LCDs that these cameras have and you won't notice until you get back to the edit room and play out to an HD monitor.
Sermon over....
Alex,
I am demoing the XH-A1 and Sony V1e tomorrow and will have a look at the autofocus system on the A1 to see if I can replicate your issues. I'll be in the HD club by the end of Saturday afternoon! :)
TT
Alex Leith December 8th, 2006, 06:55 AM Thanks guys for comments and help so far...
Tony - I'm totally with you on semi-auto. I've NEVER shot with AF left on... (well maybe once or twice)... but what I do feel I have a right to is a camera that works properly.
I cannot even use the "push-to-grab-focus" workflow, because the IAF button either shunts the focus the wrong way, or is painfully slow taking up to 8 seconds to get focus.
I've NEVER had a camera that displayed either of those phenomena before.
What I want to assertain (and thanks for offering to help) is whether the phenomena I've seen are just unfortunate quirks of this camera and I'm being oversensitive (as usual).
Greg - I might have thought it was a back focus issue, but focus holds in manual focus. However, I've just noticed in the manual that it states "Autofocus may not work on faster zoom settings". I'm starting to think that the pulsing and the focus on zoom issues could well be to do with the single motor focus/zoom assembly of the lens. A bit crummy really.
If that's the case (and I'd love other people to try it on theirs to see if it is) then I'm still left with very slow focus response.
Thanks guys
Tony Tremble December 8th, 2006, 07:08 AM Alex
Is there anything obscuring the IAF sensor?
Do you know whether the camera has two servos one for zoom and other for focus? If its just one then that might account for the pulsing of focus in that latest clip. Does anyone else know??
On these slow creeps does it happen all the time? If you speed up the zoom does the pulsing happen at a similar rate?
Don't worry about being overly sensitive as you rightly point out you deserve to have a fully functional camera for the best part of £3k. I'd be the same in your position. The beauty of video is that many people shoot many different things and that can highlight problems that others have not noticed or will ever notice.
Anyway check back on Sunday and I'll let you know what I've found.
Cheers
TT
Alex Leith December 8th, 2006, 08:11 AM Thanks Tony, there's definately nothing blocking the IAF sensor (I tried with the lens hood on and off, and I even gently cleaned the sensor with my lens cloth).
The pulsing on slow creeps only happens when the autofocus is on. And it does seem to pulse at a rate that is related to the speed of the zoom.
I look forward to your findings.
Cody Lucido December 8th, 2006, 08:24 AM I have not experiencd that pulsing seen in your clip on my A1. Although I have noticed it having difficulty when trying to find focus on things like clouds. But I do not leave the IAF on EVER. Manual focus or use your focus preset.
You might want your camera to be looked at.
Chris Hurd December 8th, 2006, 08:36 AM I've sent my XH-A1 back to the dealers because of problems with the focus... However, they had a quick play and say the performance is normal. But I'm convinced it's not right... help me to convince them to send it back to Canon for repair...
Alex. You're going about this in the wrong way completely.
Stop posting on message boards and get your camera in to Canon UK service immediately. You should not have to go through your dealer. I understand that your dealer is saying this is normal, however your dealer is not Canon service! Only when you send your camera to Canon service will you get a definitive answer as to what is going on and whether or not something is wrong with your camera.
An internet message board is going to do nothing conclusive for you. If you're serious about this camera, then you *must* get it into the Canon factory service center over there just as soon as you possibly can. That's the only way you can know for sure. Again, if your dealer says there's nothing wrong, well that's fine but it's not a definitive answer. You should be able to contact and interact directly with Canon factory service without having to go through your dealer or anybody else.
Please do so immediately, and be sure to report here how this goes for you. Thanks in advance,
Michael Mann December 8th, 2006, 09:11 AM Chris, I completely disagree that Alex should stop posting his problems here. Doing so is helpful for all who are about to buy this cam - like myself.
Best regards, Michael Mann
Chris Hurd December 8th, 2006, 09:24 AM No it is not at all helpful for those who are about to buy this cam, because there is nothing conclusive about Alex's situation until he can get a definitive answer from Canon service. His camera is either operating properly or it is not. The only conclusive way that this can be determined is to obtain a verdict from Canon service. Efforts by other owners to duplicate his issue will have too much variation despite their best intentions. The whole point of this forum is to be helpful to those who are about to buy or already own the camera. Nothing helpful can be derived from this until Alex submits his camera to the Canon service department and reports their conclusions here. That's the only way that we'll know for sure if there's actually a problem. Thanks in advance,
Pete Bauer December 8th, 2006, 09:32 AM Chris is correct -- not because he owns DVinfo -- but because we are obviously well past the point of realizing that what Alex really needs to know is if his camera is, or is not, functioning within Canon's spec. Only Canon is going to be able to establish that. We'll be eager for that answer, but until then it is all just idle chatter. If it is faulty, well, bad luck and they'll get it fixed or replaced. If it is in-spec, then that's information that might guide Alex and others in their choice of cameras. But until Canon looks at the camera, it is all just off-the-cuff opining, or worse.
EDIT: Ah, Chris beat me to the punch. Although he said it better, we're saying the same thing...must be something to it!
Chris Hurd December 8th, 2006, 09:41 AM But until Canon looks at the camera, it is all just off-the-cuff opining, or worse.And it doesn't become helpful until Alex tells us what Canon has to say about his camera.
Michael Mann December 8th, 2006, 11:32 AM Chris, I see your point, but I still disagree:
Of course I hope we get a verdict by Canon to see whether this behaviour is normal or not. But I find the fact alone that (maybe only) Alex's A1 shows the described behaviour a RELEVANT information. (My MH10 does the same, maybe that's why.)
No offense, Michael Mann
Luc Meisel December 8th, 2006, 11:39 AM This is absolutely an issue that should be on the boards because
I want to know about it,
I want to ask about it if I go to buy one.
He should be able to ask others if they have the same issues.
My Hv-10 which i assume may have the same parts in the IAF
does keep focus sometimes when zooming, it would be hard to believe that the more expensive model couldnt do this.
Thats not to say that the Hv-10 doesnt lose focus or hunt, cause it does.
It loves to hunt and if you zoom too close it doesnt focus at all on a close object.
I am going to a dealer today to test and ask about this.
Thanks for the post.
Chris Hurd December 8th, 2006, 11:54 AM Alex said himself that this might be a case of unrealistic expectations about how the IAF operates... so again, it's not a even a "real" issue until he knows one way or the other if his camera is faulty. Like I said... we won't know that to be a fact until he sends it to factory service and gets an answer.
Until then, it's not a fact. I'm not operating this board in order to start rumors. This site is intended for factual information only. We don't have any facts yet. The only fact available to us is that Alex is not sure what is happening with his camera.
Vlad Manning December 8th, 2006, 07:12 PM Doesn't sound like anyone is trying to start any rumors to me, just the original poster noting odd focus behavior -and Dave Lammey noting his HV10 displays the same when the IAF quickly hunts. And that fact brought up of the Canons overlap of AF zoom function is also worth knowing.
It's your forum Chris, but I've found the more a tech forums posts get restricted or censured, the less useful it becomes. Let people speak freely.
Chris Hurd December 8th, 2006, 07:25 PM You might be in the wrong place then, Vlad, because this site is without a doubt one of the most heavily restricted tech forums on the web. It's also one of the most popular tech forums for digital video precisely *because* of those restrictions. And I'm not stopping anyone from speaking freely... the internet is huge and I encourage everyone to exercise their right to freedom of speech and start their own web site / message board / blog / whatever, and run it exactly the way they want to. Meanwhile, I'll continue to run mine as I see fit, and that particular way has always been to filter out as much noise as necessary in order to keep the signal level as high as possible. That's how we define usefulness around here. Thanks in advance for understanding,
Luc Meisel December 8th, 2006, 11:00 PM I think that so called facts almost always start as an hypothesis.
The hypothesis is to figure out if this persons IAF is faulty.
The fact can also be understood, if compared to others cameras
Though subjective it is still a fast and valid method to procure information.
The example would be that I went out and tested 2 A1's at different stores.
Neither of them displayed what we're speaking of, I then bought one and will test that unit.
Obviously my testing is a simple visual procedure but valid still.
So it is very useful if he determines that it helped him gather the information to move to the next step which would be to send it in.
The first step is NOT to immediately send in the camera, why let go of your new camera, until your sure.
I think that Vlad is posting in the RIGHT place, anywhere that he posts is the right place if its where it is helpful to others, is that not what this board is for.
So, I found it very helpful, thanks, love your post.
and I will post new info on my new cam and see if it does this.
Holly Rognan December 8th, 2006, 11:50 PM I agree with Chris. He has restricted my speech, and refined it to a more pleasing demeanor in the past, and I respect it. My negativity may have been warranted by bad experiences, but it didn't help anything, it was meaningless whining banter.
I appreciate the usefulness and relevance that this forum offers.
I haven't found anything so succinct and pertinent to my questions, and I find it very mature and objective. If I have a question, I usually find it very quickly.
That is not to say that subjectivity is not desired here, it is very much a core function. But once things debated to personal bias and conflict arises, Chris quickly becomes a mediator and stomps out the posibble fires.
I hear your pain Alex. I have had significant problems in the past with Canon's customer service and faulty lens elements not properly focusing. If you feel that something is wrong, send it in with a tape highlighting the problem and be firm in your decision to have them thoroughly fix it. It is too bad that you possibly got a bad unit after spending a good chunk of change. I can only hope that Canon treats you well and makes things right with you.
Chris Hurd December 9th, 2006, 01:39 AM The hypothesis is to figure out if this persons IAF is faulty.The only way that can be accomplished with any degree of certainty is for Alex to send his camera in to the factory service center. And that's what I've been urging him to do (and to please report back to us as well), so that we will all know for sure whether there is or is not something wrong with his camera.
The first step is NOT to immediately send in the camera, why let go of your new camera, until your sure.You don't seem to understand. The only way that he *can* know for sure is to send it in to the authorized factory service center. That's the entire goal, to figure out if there's something wrong with the camera! The *only* resource available that can provide him with a definitive answer is the Canon factory service center.
Chris Hurd December 9th, 2006, 02:25 AM And with that, I'm closing this thread for now until Alex is ready to report back.
Alex Leith December 18th, 2006, 10:47 AM Thanks to all those who offered their suggestions and tested their cameras for me.
On Friday Canon confirmed the camera was faulty and shipped out a new one, which I will get tomorrow. Hooray! Just in time for Christmas. :-D
Josh Chesarek December 18th, 2006, 11:04 AM I am glad you are getting a new camera. Might I suggest updating your webpage for people who are only checking there for info? :)
Chris Hurd December 18th, 2006, 11:19 AM Many thanks for the update, Alex -- I've changed the title of this thread to suit.
Much appreciated,
Michael Mann December 26th, 2006, 04:47 AM Alex, meanwhile I have noticed, that my A1 shows the very same zoom focusing problems like the ones you described in this thread. (I can upload a short file for documentation if anyone is interested.)
Please let me/us know whether you new camera gets rid of this problem. Thanks in advance.
Alex Leith December 26th, 2006, 05:53 AM Hi Michael. Until about half an hour ago I thought that my new camera had fixed *all* the issues that the previous camera had.
However, after reading your message I tested the "focus-pulsing-during-zoom-with-auto-focus-on" problem on this camera... and I can confirm that it does display it too.
I certainly don't have any of the other AF and IAF issues that I had before (AF and IAF are now quick, stable and pretty reliable). But it does have the focus pulsing. It's much less pronounced - I would say almost unnoticable through the viewfinder or LCD, especially on faster zooms. But it's there.
I suspect this may be a weak point in the design of the camera...
Philip Williams December 26th, 2006, 05:58 AM Hi Michael. Until about half an hour ago I thought that my new camera had fixed *all* the issues that the previous camera had.
However, after reading your message I tried a test of the "focus-pulsing-during-zoom-with-auto-focus-on" problem... and I can confirm that this camera does display it too.
I certainly don't have any of the other AF and IAF issues that I had before(AF and IAF are now quick, stable and pretty reliable). But it does have the focus pulsing. It's much less pronounced - I would say almost unnoticable through the viewfinder or LCD, especially on faster zooms. But it's there.
I suspect this may be a weak point in the design of the camera...
Hi Alex, thanks for the update. Quick question, are you seeing the pulsing in 24F, 30F or 60i? If you haven't tested that out yet, try to compare 24F and 60i on the same subject/environment...
Alex Leith December 26th, 2006, 06:34 AM Quick question, are you seeing the pulsing in 24F, 30F or 60i?
Interesting...
I tried the test again (I'm in Europe, so it was at 25F and 50i).
At 25F the pulsing is slight but noticable on out-of-focus portions of the image during slow zooms at the long end of the lens. It pulses at around 4x per second at ZS 1 and gets faster on quicker zoom speeds. By ZS 8-10 you can't really see it because the image is moving too quickly.
At 50i the pulsing turns into a much slower oozing! You probably wouldn't notice it if you weren't looking for it, but it slowly pulses once every 2 to 3 seconds at ZS1. Again at faster zoom speeds it oscilates faster, but it becomes more or less imperceptible by ZS 4-6.
Raymond Toussaint December 26th, 2006, 09:06 AM And its gone with manual focussing and zooming. Zoom in -focus - zoom out -start shot - zoom in. Like you do with all the professional lenses.
Philip Williams December 26th, 2006, 09:45 AM After I noticed this phenomena a couple of weeks ago I did some testing. I found that situations that are challenging for auto focus cause a pulsing focus when zooming in or out in 24F mode. The exact same shots and zooms in 60i were fine (I was watching live output on a 42" display to watch any focusing issues). As Raymond just mentioned, setting the lens to Manual Focus elimates the pulsing altogether.
If I had to guess, I'd say this pulsing is related to auto focusing issues that most (all?) 24P camcorders have. The XH A1 actually finds focus fairly quickly in 24F mode, probably much faster than many other 24P camcorders. Perhaps the downside to this faster focusing at slower framerates is the focus pulsating back and forth as it tries to compensate for zooming? It would be interesting to compare the XH auto focus to some of the other 24P camcorders in a controlled test.
In any event, I think Raymond is pretty much right on. Especially in 24F, I'm just going to shoot manual focus only. The focus ring is pretty decent, the lens holds focus well and the distance readout plus peaking makes it pretty much bullet proof.
Michael Mann December 26th, 2006, 12:18 PM Hi Michael. Until about half an hour ago I thought that my new camera had fixed *all* the issues that the previous camera had.
However, after reading your message I tested the "focus-pulsing-during-zoom-with-auto-focus-on" problem on this camera... and I can confirm that it does display it too.
I certainly don't have any of the other AF and IAF issues that I had before (AF and IAF are now quick, stable and pretty reliable). But it does have the focus pulsing. It's much less pronounced - I would say almost unnoticable through the viewfinder or LCD, especially on faster zooms. But it's there.
I suspect this may be a weak point in the design of the camera...
Alex, thanks for your fast reply.
You can download two short native demonstration clips here (25F, fast auto focus mode):
http://www.filefactory.com/f/f5656740836b15ad/
The problem only occurs in either of the two auto focus modes. If I switch to manual focus, the problem is gone.
Since I use manual focus in most cases I really can live with this "problem". But sometimes - when doing snapshots for example - I just have no time to focus manually, and then the "pulsing" results are very annoying (see clips above).
By the way, my HV10 shows a similiar focus pulsing when zooming.
Chris, I suggest to change the title of this thread again, since this focus pulsing issue does not seem to be solved at all.
Alex Leith December 26th, 2006, 01:22 PM The exact same shots and zooms in 60i were fine (I was watching live output on a 42" display to watch any focusing issues).
Personally I think I *could* see the effect in 50i too - but it was extremely subtle because it changed from a pulsing to a much softer undulation.
The XH A1 actually finds focus fairly quickly in 24F mode, probably much faster than many other 24P camcorders. Perhaps the downside to this faster focusing at slower framerates is the focus pulsating back and forth as it tries to compensate for zooming?
If it is trying to compensate for zooming then it's a fault with the design of the camera. The back-focus on the lens should be setup in such a way that as you zoom in an out the focus stays the same (and in fact it does if you turn AF off).
I personally think it's more likely to have something to do with the mechanical aspect of using a single motor for zoom and focus - especially as the rate of pulsing seems to increase as the speed of the zoom increases.
Either way, you and Ramond are correct. The best way to work is with AF off. I wouldn't normally have it on - but regardless, this effect demonstrates some sort of a design flaw if it's being seen across multiple units.
Thanks for sharing these clips Michael. You can clearly see the pulsing effect. It's fairly pronounced and makes AF effectively useless to be left on. I guess we've found (one) of the camera's Achilles heel's!
Brad Tyrrell December 26th, 2006, 01:56 PM I personally think it's more likely to have something to do with the mechanical aspect of using a single motor for zoom and focus.
- but regardless, this effect demonstrates some sort of a design flaw if it's being seen across multiple units.
Not sure "design flaw" is the right description for 1 motor instead of 2. Probably a financial decision there. The A1 boys seem to have done a pretty decent job of "two things at the same time" for one motor, - just not perfect. I bet that for more bucks ...
Alex Leith December 26th, 2006, 03:18 PM I think you're right Brad, that Canon have generally done a pretty good job with the A1. But personally if something doesn't work properly by design, I'd call it a design flaw - even if the underlying root of that flaw is one of providing a cheaper product.
One expects certain things from a product for it to be considered of "merchantable quality" - and one of those things (in my opinion) is that the advertised features work, and can actually be used.
I think we can see from Michaels clips (and my own experience with two A1s) that the auto-focus cannot be used on slow speed zooms towards the long end of the lens.
To me that's a design flaw. Just because it's a feature that isn't left "on" by most professional videographers, or just because we can be "understanding" of the problem because we're getting something at a certain price point, doesn't mean that the manufacturer can then go on to advertise it as a revolutionary new instant AF system... and not mention that you can't use it whilst zooming.
Having said all that, I am happy with my A1, even with its flaws.
Brad Tyrrell December 26th, 2006, 03:41 PM Having said all that, I am happy with my A1, even with its flaws.
Me too. Even if I can't use the lens on "full-wide" because of the barrel distortion.
Annoyed me at first, then kinda realized what I was asking. A wide angle on a zoom lens on a wide format HD video cam with no fish eye at the edges for less than $4000. Jeesh.
On-the-other-hand, just a little off full-wide and it's very usable. Of course since I don't think anyone claimed no distortion, it's not really a "design flaw". (This probably belongs in a different thread anyway.)
Michael Mann December 26th, 2006, 04:22 PM Alex, do you think Canon is or has got aware of this problem or did they just try to get you satisfied, without going deeper into it? Did they give you any plausible comment on this "pulsing problem" or did they just send you a new A1 in exchange? Thanks.
Alex Leith December 26th, 2006, 04:48 PM I didn't actually get any commentary from Canon except for them to say that the camera was "definitely faulty" (they weren't specific as to which faults they were addressing).
My dealer brokered the repair on my behalf, so I was sent a replacement from the dealer's stock. I gave it a quick test when I received it, and it didn't appear to display the pulsing or other focus problems that I had with the first unit. As you know, I've now checked more closely, and the focus pulsing is still there on this unit - albeit less noticable.
Whether Canon knows about this or not... I don't know. It would seem like something that should have been picked up at the prototype stage. Perhaps they didn't notice it; or perhaps they were constrained by their budgets to use mechanical systems that are already in other Canon camcorders - which they just couldn't get to work "perfectly" in this form factor; or perhaps they noticed it too late to make changes to the design before it shipped out; or perhaps they hoped that no-one else would notice the problem; or perhaps it's a software problem... I don't know.
Either way, I feel it's something that Canon *should* fix given that it means you can't use the AF whilst zooming - which is something that I feel you would expect of a merchantable quality AF system. I know AF isn't perfect, and can *sometimes* have problems maintaining accurate focus, but this pulsing looks like a mechanical flaw, and is not something that one would expect of any AF system.
Whether they will fix it, or just update it with the next model is another matter entirely.
Tom Roper December 26th, 2006, 07:22 PM The back-focus on the lens should be setup in such a way that as you zoom in an out the focus stays the same (and in fact it does if you turn AF off).
Wrong!
If you video something moving away from you, (picture kids sledding down a hill), as you zoom so that the object continues to fill the frame while the subject distance is moving away from you, you would not want the focus locked on the first position of the sled when it was just a few feet in front because it would go out of focus as it draws farther away.
Canon gives you the option to turn autofocus off. That's enough. If it worked as you described in auto, you could only maintain static focus on a constant camera-to-subject distance while you zoom.
Raymond Toussaint December 26th, 2006, 09:54 PM Q. The focus issue Alex described is repaired and gone. That is his word.
Q. Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do)
Focus is on subject in center of the screen, if you zoom, the image information in the center of the screen is changing, so is the focus. An object that was only for a small percentage in the center becomes the whole image. In 24F and 25F Canon has a very speedy AF compared to others.
The Canon has a Manual and TWO Autofocus systems, you can work with one of them or with two combined.
1. You can manually focus and zoom together.
1a.You can manually focus and zoom together and use Push Focus button on subject.
2. You can set focus on automatic end choose in menu:
a) AF normal autofocus (TTL)
b) IF instant autofocus (TTL and sensor, two way, fast)
If you choose for autofocus with (a)
You can focus and zoom together and hold the focusring during zoom.(override) and release if your zoom is finished.
If you choose for autofocus with (b) the system needs to recalculates faster the focus. You zoom and focus together. There is some "computerwork" but you can override the focus system by using the manual focus ring.
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.
Alex Leith December 27th, 2006, 03:02 AM Wrong!
I'm talking about the back-focus setup. When you zoom a lens in-to, or out-from a stationery object the focal point of the lens should remain constant, ie. the object should stay in focus.
I'm not saying that the autofocus should be inactive whilst zooming. What we're talking about here is an focus "aretifact" that occurs when zooming on static objects.
Q. The focus issue Alex described is repaired and gone. That is his word.
Q. Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do)
1. Unfortunately I'd been a bit hasty is declaring ALL the focus issues gone. The pulsing happens on this camera too.
2. You're absolutely right, I barely EVER have the AF on - and we've all been taught that we shouldn't really be zooming in-vision (the human eye doesn't zoom).
My point is more to do with merchantable quality of goods. If Canon advertises a feature, then that feature should be usable. It is reasonable to expect that AF could be left on, as zooming in and out is normal behaviour whilst filming something. AF cannot be left on during very slow zooms on the long end of the lens, because it produces an unpleasant effect on screen.
It's like advertising a car that has self-leveling suspension, but not mentioning that you can't drive it up hills.
Michael Mann December 27th, 2006, 03:29 AM Q. The focus issue Alex described is repaired and gone.
Unfortunately it is not. Please have a look at my example clips I posted earlier.
Q. Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do).
I do. I sometimes simply have no other choice since there is not enogh time to focus manually. Either AF or snapshot is gone.
I guess we all can live with this AF malfunction during slow zooms. But I completely agree with Alex that this pulsing is NOT what one would accept of any AF system - alll the less since Canon praises its design as new and revolutionary. The AF system of my former FX1 didn't pulse at all during slow zooms, so it never ruined a zoom shot like my new A1 does in AF.
Chris, as soon as you find the time please change the title of this thread, since the problem is NOT solved. The actual title is misleading for users - and for Canon, when they browse through user feedbacks to get input for a coming firmware update.
Philip Williams December 27th, 2006, 06:05 AM <snip>
Zoom and focus in AF together the same time (how often do you want that? or work that way, but that is another question, I never do)
<snip>
Actually I have to admit that I do this sometimes at weddings. A slow zoom in on the bride and groom can play quite nicely, but a kung fu snap zoom would probably be... unwelcome. If I'm in manual focus and off a bit, it won't really show at the wide end - but would become apparent and quite awkward as the zoom nears the subjects. In this case its not something you can correct during the zoom since the lens doesn't allow you to focus while zooming.
Now having said that, let me clarify that I perceive this phenomena at 24F and don't plan to shoot weddings at that frame rate. I'd shoot a typical wedding at 60i unless requested otherwise, and I have not noted the pulsing zoom at 60i so I'm not concerned. However, since the pulsing focus is possibly related to the AF sampling rate, I could see this being an issue for PAL users under more typical shooting scenarios as opposed to NTSC users.
Raymond Toussaint December 27th, 2006, 06:14 AM Alex his camera was faulty and is replaced, he did not have the going in - out focus problems anymore. Canon fixed that matter. That you see minimal pulsing on the big screen while doing zoom in with AF on, is something you can avoid.
Michael: there are many very happy A1 shooters at work on the moment I did not hear anyone complaining like you do. You complain about everything.
Can you try to shake the camera hard (what you did before) while zooming with AF on at the same moment, and describe what is happening? If you can't see it on monitor, try a 42" screen, please report your findings.
Raymond Toussaint December 27th, 2006, 06:21 AM If I'm in manual focus and off a bit, it won't really show at the wide end - but would become apparent and quite awkward as the zoom nears the subjects.
If you track in and zoom in at the same time to 'soften' the starting point of the track you can do that with autozoom. You can (pre) manual focus and/or use the PUSH focus button to help you out.
Is done many times, professional lenses don't have autofocus, but have autozoom. Canon gave us the 3 ring lens, use it.
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