View Full Version : PMW-EX1 Auto Focus Slow?
Steven Thomas November 30th, 2007, 01:33 PM Please check your camera's AF response time.
Even under good light with good contrast and aiming at objects with vertical line structures, my camera is reponding real slow in AF mode?
Sometimes it may take as long as 6 seconds or more to focus. Sometimes it does not. Also looking at the DOF LCD indicator, it appears to hunt around even though it's locked on the subject.
Any thoughts on this and what you all are seeing?
You would not be able to use this in a run-and-gun situation, well unless you don't mind your shots out of focus. ;)
Dave Elston November 30th, 2007, 01:47 PM Also looking at the DOF LCD indicator, it appears to hunt around even though it's locked on the subject.
I believe the DOF LCD indicator could well show varying values when focus is locked as it is governed/determined by the aperature and zoom position, not by the point of focus itself. That's my understanding of this feature as described in the manual. In conditions where iris or FOV(zoom) is varied the DOF will also vary.
I can't comment on AF response though, waiting until January before I make the purchase.
Craig Seeman November 30th, 2007, 02:05 PM Steven, I could have sworn there is a speed control for autofocus in the menus. I remember seeing that for sure for ATW (auto white balance).
Piotr Wozniacki November 30th, 2007, 02:53 PM ATW is sompletely different in that you actually might not want it to react to any fast or accidental light tempererate changes; autofocus shhould alwayd perform as quick as possible.
Eric Pascarelli November 30th, 2007, 03:00 PM I'll check my camera. It certainly seems faster than the HVX!
Craig Seeman November 30th, 2007, 03:07 PM Maybe turning on/off MF Assist impacts speed?
Steven Thomas November 30th, 2007, 03:33 PM Maybe turning on/off MF Assist impacts speed?
It defaults OFF, I can try on. You never know, although this feature is for
using AF to get you closer after you make a manual focus adjustment.
I will try turning it on.
Steven Thomas November 30th, 2007, 07:23 PM There's no control parameter for AF speed.
Also, even when mine finds focus it continues to hunt.
Once it finds focus, it modulates just slightly in and out.
It happens from wide through various ranges through the zoom travel.
Yes, there's decent light and objects that can grab focus. I even tried it outside in the daylight.
As suggested by Craig, I've tried to see if the MF assist impacts it.
No difference.
You can even display the focus distance/DOF display item and watch
it slightly move around from left to right on the focus distance line.
Very strange.
Has everyone got a chance to determine if their camera has this problem, or am I just "bad luck to a hunting dog?" LOL
Actually, this is no laughing matter....
Also, again the AF is running real slow. Usually takes 3 to 6 seconds, or not at all.
Craig Seeman November 30th, 2007, 07:35 PM I tested AF at my dealer yesterday. Had about 3 hours hands on with the camera. While it wasn't as fast as my PD170, it seemed ok. It did seem a bit slower when I was zoomed in and moved it to a neighboring object vs wide though.
Steven Thomas November 30th, 2007, 07:38 PM Thanks Craig.
When you say a bit, are we talking 3 to 6 seconds?
Also, I was real surprised how slow it was even at wide where DOF is huge.
Craig Seeman November 30th, 2007, 07:44 PM 3 seconds seems right when I was zoomed in and moving from one object to a an next to it but further away. It didn't concern me because in those situations I'd using Push Auto when doing "run and gun" and that worked fast (it seemed to me). When I was wide I didn't notice the issue.
The only time I resort to auto is when I'm tracking an object with changing focus so Push Auto would be awkward. That's a bit different than changing the "point of interest" from one object to another.
Actually a good test would have been someone walking towards me/the camera but I didn't try that.
To test auto having two people standing at different focal points might have worked (moving from near face to far face for example).
Steven Thomas November 30th, 2007, 07:57 PM Hmmm.
Maybe mine's the same.
Does yours hunt.
You will probably need a monitor hooked up to see it.
Also, if you turn on the focus/dof display item (Lens Info), you can actually see the focus point wandering around on the line.
You can turn this on by first setting your camera to manual AF operation, then push the USER 1 button. By hitting that but again it changes from meters to feet. This is aasuming you have not reconfigured the switch fro the "Len Info" setting. Now switch back to AF mode and check it.
Kevin Shaw December 1st, 2007, 01:55 AM I got my first hands-on look at the EX1 tonight, and both myself and a friend felt the AF response was unsatisfactory. Bummer. :-(
Steven Thomas December 1st, 2007, 09:23 AM Once it locked focus, did you look to see it there was still a small amount of "hunting"?
Mine finds focus, then slightly moves back and forth trying to readjust.
This happens even under good light and objects with good contrast.
You have to look for it using a decent monitor, but you can visually see it "breathing" in and out of focus.
Craig Seeman December 1st, 2007, 12:13 PM That's why I mention the MF assist. It will try to "walk the focus in" and I can imagine in many circumstances that's not a good thing. Whenever you see it hunting, see if changing MF Assist impacts it.
Once it locked focus, did you look to see it there was still a small amount of "hunting"?
Mine finds focus, then slightly moves back and forth trying to readjust.
This happens even under good light and objects with good contrast.
You have to look for it using a decent monitor, but you can visually see it "breathing" in and out of focus.
Leonard Levy December 1st, 2007, 02:07 PM This is all pretty typical with 24 progrssive on all the cameras isn't it. Not very good on the HVX either- lots of hunting.
Steven Thomas December 21st, 2007, 10:57 AM Any more on this?
There's times my camera will not even lock onto focus at all.
No, I'm not shooting a bare wall ;), this is aiming right at well lit high
contrast objects.
Thierry Humeau December 21st, 2007, 06:28 PM Auto focus is indeed slow on the PVW-EX1 and I have no intend to use it as the manual focus ring is probably one of the primary reason I liked the EX. It works well but it takes a lot of turning to go form closeup to infinity and it is not quite as smooth as a 15K HD lens. That said, people who have struggled manual focusing on the Z1 or HVX-200 will be very pleased.
I feel there is something inerant to motion pictures acquisition that will never allow autofocus systems to work well. Take for exemple a "rack focus", there is no way a computer chip will ever figure this one out.
Thierry.
Thierry Humeau December 21st, 2007, 06:33 PM And I forgot to mention the iris ring, even better than the focus one. Smooth, no stair stepping, very fine control of your exposure. Again, as for focusing, I rarely use auto iris.
Thierry.
Evan Donn December 21st, 2007, 07:36 PM I feel there is something inerant to motion pictures acquisition that will never allow autofocus systems to work well. Take for exemple a "rack focus", there is no way a computer chip will ever figure this one out.
Perhaps - but maybe that's just because having a computer drive an electric motor which moves a complex mechanical lens system to try and focus an image that the computer can't see or understand is the wrong approach. A better approach would be to not have to worry about focusing at all while we're shooting - let the computer deal with focus in post so that we can keyframe things like racks or track moving subjects.
It sounds a little 'sci-fi'... until you've seen this: http://graphics.stanford.edu/papers/lfcamera/
(make sure you watch the video: http://graphics.stanford.edu/papers/lfcamera/lfcamera.avi)
Now that your mind is suitably blown, back to the EX. I suspect the slow autofocus is simply the price we have to pay for having a true mechanical lens - it's got to be much easier to make a fast, smooth and quiet autofocus when you don't have to have the lens elements coupled to gears meant to be turned by a large outer ring.
Malcolm Hamilton December 22nd, 2007, 10:14 AM For me, this news about the slow auto-focus is certainly bad news. I might get no sympathy from most of you on this forum - - you're talented camera operators who love (and deserve) the manual zoom, manual iris, etc.. But I'm just coming to camera work (from producing, directing and editing), and I've been using autofocus almost exclusively (with the Sony Z1U) for the last five months. So, why don't I get stick with the Z1U, or get another camera like it, with a cheaper lens (that can autofocus)? Maybe I should. But I really wanted to get away from tape-based shooting, and I like the fact that the EX1 can shoot in lower light levels (requiring less lighting, another area I feel inadequate in).
Any advice? Is the autofocus on the EX1 so bad as to make it essentially UNUSEABLE?
Let me add this about how I shoot, in case I could get by with manual focus (and just don't know it) - - for most of the shooting I do, I seldom zoom... I usually stay zoomed out (if I want a tighter shot, I move closer). Would this simplify things for me, re focusing?
If people here advise me to NOT get the EX1, is there another camera you would suggest (flash-card based; able to shoot in low light, etc.)
Thanks,
Malcolm
Craig Seeman December 22nd, 2007, 10:32 AM Malcolm, btw I'd been editing nearly 20 years before I started shooting so I do know where you're coming from.
When using my PD-170 I relied on Push Auto since trying to deal with that servo controlled ring was a pain. Having "full manual" control is a blessing. I can focus fast since the ring allows me to.
That said, there is a variety of different "auto focus" situations so the camera response may not be "equal" in all those situations.
It may be one thing to move from one object to another in different focal planes. That might be slow for this camera to respond.
It's another to track a single subject changing the focal plane.
In other words, tracking a single moving object may be different than switching objects, so I'd test those two circumstances separately.
There's also lighting/contrast as a factor and the speed at which it change may be affected by that too.
Think about how the auto focus works and discerns the subject.
So the tests (that I can think of)
high contrast tracking a subject
low contrast tracking a subject
high contrast changing a subject
low contrast changing a subject
one might also try auto always on vs manual with push auto.
Jon Nelson December 22nd, 2007, 10:45 AM This EX1 autofocus news is BAD
Focus is my #1 issue in HD
Coming from big cameras with real (& expensive) viewfinders with which we have a hard enough time "estimating" focus... the small cameras with really inferior monitoring and often using them at arms length from our eyes and usually not in the best lightning conditions... well, autofocus that works is a great (necessary) tool!
A 2" viewfinder on the big cameras just can't cut it for HD focus. Heck in Sd the producer would look at the 8" CRT and say "it's soft". Now in HD we need a 17" or 24" display to even estimate what it will look like on a 42" or larger panel to the viewers at home
For us, the small cameras are a different tool than the big cameras - with the small format you can shoot in styles that the big cameras can't, they are just too big. But, autofocus is critical in these fast, documentary style, handheld situations
The HVX200 autofocus was/is a joke. The Canon A1/G1 autofocus works incredibly well! To think we'll take a huge step backwards in autofocus with the EX1 is not good news!
Malcolm Hamilton December 22nd, 2007, 10:54 AM thanks, Craig, for your reply.
I can't test the camera out, as I don't have one (I was on the verge of buying one, when I saw this thread)... but I hope others, who do have the camera, continue to weigh in on this.
I'm concerned because of what Steven Thomas, says, i.e. - -
”There's times my camera will not even lock onto focus at all”
... to me, that means the autofocus is unuseable!
But then, Leonard Levy says:
“This is all pretty typical with 24 progrssive on all the cameras isn't it. Not very good on the HVX either- lots of hunting”
... does this mean that if I shoot 30 fps, autofocus might work better?
Thanks,
Malcolm
Craig Seeman December 22nd, 2007, 11:22 AM Jon, you apparently haven't used the LCD with with the EX1. It's beyond anything I've seen in detail on a camera LCD. With both Expand Focus and Peaking as a choice (and while in record too) I can nail focus pretty fast in full manual.
This EX1 autofocus news is BAD
Focus is my #1 issue in HD
Coming from big cameras with real (& expensive) viewfinders with which we have a hard enough time "estimating" focus... the small cameras with really inferior monitoring and often using them at arms length from our eyes and usually not in the best lightning conditions... well, autofocus that works is a great (necessary) tool!
A 2" viewfinder on the big cameras just can't cut it for HD focus. Heck in Sd the producer would look at the 8" CRT and say "it's soft". Now in HD we need a 17" or 24" display to even estimate what it will look like on a 42" or larger panel to the viewers at home
For us, the small cameras are a different tool than the big cameras - with the small format you can shoot in styles that the big cameras can't, they are just too big. But, autofocus is critical in these fast, documentary style, handheld situations
The HVX200 autofocus was/is a joke. The Canon A1/G1 autofocus works incredibly well! To think we'll take a huge step backwards in autofocus with the EX1 is not good news!
Kit Hannah December 22nd, 2007, 12:03 PM Just for reference here...
What other "professional" lens has Auto Focus anyways? This is a real Fujinon Lens for the most part and there are going to be some drawbacks when trying to integrate consumer or prosumer grade features into a camera of this caliber. Personally, I would have rather they left off the AF completely, because when dealing with other professional cameras, its not typically going to be an option. I understand that the EX1 was made in the smaller form factor, but for people used to a professional camera and lens, AF being a bit slow is not a big problem. It will probably only create issues for people stepping up from lower end cameras.
David Elkins December 22nd, 2007, 12:22 PM Just for reference here...
but for people used to a professional camera and lens, AF being a bit slow is not a big problem.
My thoughts exactly, I have rarely, if ever, used AF on the DVX100 I bought years ago I am so used to all manual lenses. This is by no means a deal breaker for me. But, does the EX1 have a push auto function? I have used that a few times and found it handy when my eyes get screwed up from wind or salt water.
Evan Donn December 22nd, 2007, 12:29 PM A 2" viewfinder on the big cameras just can't cut it for HD focus. Heck in Sd the producer would look at the 8" CRT and say "it's soft". Now in HD we need a 17" or 24" display to even estimate what it will look like on a 42" or larger panel to the viewers at home
...
The HVX200 autofocus was/is a joke. The Canon A1/G1 autofocus works incredibly well! To think we'll take a huge step backwards in autofocus with the EX1 is not good news!
I have an A1 and I've never tried the autofocus. However, I don't use an external monitor and I've never had trouble focusing on the LCD with peaking turned on - and from everything I've read here the LCD on the EX is far better, as is peaking, than on the A1. I can't imagine it's going to be difficult to focus. In either case, I'd rather have a whole shot look a little soft than risk have the autofocus hunting in the middle of a shot.
Malcolm Hamilton December 22nd, 2007, 12:42 PM It will probably only create issues for people stepping up from lower end cameras.
I hear what you're saying, Kit (and other contributors, like Evan, seem to agree that for pro users, poor autofocus isn't going to be a problem). If you don't mind, though, now I'm wondering how tricky it might be for me to get the hang of manual focus, and I'd love any advice. As I say, I'm a bit new to shooting - - I realize this perhaps means I should stick with the Z1, but I'd like to upgrade for the reasons I gave before (mostly: sick of tapes & want to get into editing faster; also, want to do less lighting).
I'd love know how hard it would be for me to learn to focus manually... I'd hate to start messing things up by shooting soft... Is the EX1 display so good (people are raving about it) that this is unlikely?
And here's my other question again (sorry if it sounds a bit silly) - - the fact that I mostly shoot with the lens zoomed out completely (if I want a tighter shot, I move closer) - - would this make it easier for me to stay in focus, in manual? (I realize that if I want to shoot someone walking towards the camera from 50 feet away, I'd have to be changing focus as they approach and pass me; but if I'm walking along beside them, if I stay zoomed out, I shouldn't have to adjust the focus, right?)
Thanks for your patience,
Malcolm
Steven Thomas December 22nd, 2007, 12:51 PM I've been waiting for more info regarding the AF, hence this thread.
This question stems from the possibilty that there is something wrong with my camera. Now, I'm starting to wonder if this is across all EX1 cameras. From using other cameras, I know that AF can be questionable most of the time. Due to the nature of AF sampling, you need to use a higher frame / shutter rate. Using interlace, since two fields roll by per given frame, it tends to work the best. Therefore, ideally 720 60P or 1080 60i should be selected.
Having said that, here's what i've found with the PMW-EX1. Even if the camera is stationary and aimed at good high contrast structures, it will not lock and rest. It breathes (pulses) in and out at a steady rate.
I'm not sure how Sony has setup the AF matrix, 5 point, center weighted, full field matrix, etc, but it's apparent that it needs to be tweaked. I would believe firmware could accomodate this problem. Once it locks on its strongest peaking, it needs to stop servo. It could be their AF servo window is small. Once the camera sees it highest peak, they probably need to open the limits up just a bit.
To test for what I'm seeing.
1. Set you camera on a tripod under adequate light.
2. Set the camera to 1080 HQ 60i (1/125) or 720 60P (1/125)
3. Slide the lens to AF/MF away from body.
4. Slide AF switch on side if lens to "Auto" position. (Full AF is now on)
5. Turn menu option "MF Assist" OFF.
6. Turn ON "display info" to show DOF LCD display.
7. Turn ON "Peaking" and set its menu Level setting to "high".
The last two steps will aid in watching the AF problem.
8. Set the camera/tripod about 10' from your zoom in a bit and allow the camera to focus on your high contrast objects.
In my case, you can watch it pulse in and out of focus for about 8 seconds or longer. NOW, if you turn ON the "MF ASSIST" menu option and readjust to make the AF system work again, It will pulse almost continually and never stop.
If you shut off the the AF switch to "MANU" manual position, this allows the camera to be in manual / AF with the option to press the bottom AF push button for auto focus assist. Now, using this switch it starts to auto focus continually pulsing in and out just like the full auto focus mode.
Please try the above test.
Even using the camera under normal wide conditions when your doing run-and-gun, even with the wide DOF you can watch the focus breathe. Using the LCD DOF lens info feature, you can waych that bounce around while the AF pulses.
I know AF has never been that great on a lot of cameras, I know, I've used them. My concern is with the continuous pulsing issue.
I known a lot of users, including myself never use AF. But, this should at least work to some degree. I understand hunting when there's moving images, but when capturing with the camera not moving shooting stationary objects with good light and good contrast, this should "lock" servo, not pulse.
Evan Donn December 22nd, 2007, 01:03 PM I'd love know how hard it would be for me to learn to focus manually... I'd hate to start messing things up by shooting soft... Is the EX1 display so good (people are raving about it) that this is unlikely?
And here's my other question again (sorry if it sounds a bit silly) - - the fact that I mostly shoot with the lens zoomed out completely (if I want a tighter shot, I move closer) - - would this make it easier for me to stay in focus, in manual? (I realize that if I want to shoot someone walking towards the camera from 50 feet away, I'd have to be changing focus as they approach and pass me; but if I'm walking along beside them, if I stay zoomed out, I shouldn't have to adjust the focus, right?)
Thanks for your patience,
Malcolm
Generally the wider the lens the less critical the focus, so yes, in your example it's not likely you'd have to change the focus. Zoom all the way into your subject, focus using peaking (and magnification if necessary) then zoom out and you should be absolutely sharp.
In situations where things are moving around outside of your control it becomes about getting good at estimating distance and knowing what your depth of field is - in fact your method of staying wide and moving the camera closer is the best practice because it gives you more room. Find the distances at which the wide angle gives you a good close up, medium, and long shot and learn to eyeball those distances so you can keep the camera in focus by moving it rather than by changing the focus.
Doesn't the EX have a push-button 'focus cleanup' type mode where you get it close manually and then hitting the button refines it using the autofocus system? Has anyone tried this, and if so is it any good? That seems like it might give you the best of both worlds because it lets you tell the camera approximately where to focus and it thenhas a much smaller range to seek within - assuming it's a momentary thing you can trigger and not a full time mode which can hunt when you don't want it too.
Leonard Levy December 22nd, 2007, 01:07 PM Progressive is hard for auto focus systems generally. The DVX or HVX are fine at 60i but very slow and continually hunting at 24P. The Z1 never had true 24P that's probably why it was faster.
I don't know whether 30P would be better but it might since it samples more often.
Evan Donn December 22nd, 2007, 01:09 PM I known a lot of users, including myself never use AF. But, this should at least work to some degree. I understand hunting when there's moving images, but when capturing with the camera not moving shooting stationary objects with good light and good contrast, this should "lock" servo, not pulse.
You're absolutely right, that does sound like an error of some sort. Does the EX have an external focus assist sensor like the A1? If so, where is it located and is it possible something is obscuring it or it's dirty?
Malcolm Hamilton December 22nd, 2007, 01:25 PM Evan, thank you so much for this advice. It sounds do-able for me; I'll weigh and balance the benefits and challenges of the EX1 (at least I now know I could probably learn to focus manually), vs., I guess, the Canon XH A1, that boasts about its Instant Autofocus.
I do appreciate the help,
Malcolm
Kit Hannah December 22nd, 2007, 04:12 PM Honestly, the only auto focus I have ever used is the XL1 and it too teneded to refocus even on a static shot (borrowed one from a buddy for a 3rd camera). It was annoying as hell trying to edit. Manual focus in my book is the only way to go. As someone mentioned earlier, zoom all the way in, focus, and anything in that plane is going to be in focus no matter how far you zoom out. Wide shots are definitely more forgiving, but overall, manual focus is pretty simple. It will take you all of 10 minutes to learn, another little bit to master and you'll never look back. All you hae to do is turn the focus wheel until your subject is sharp. They say that HD is much harder to focus than SD, but most of these new cameras have some sort of focus assist, where the edges will glow when things are in focus. Point is, you'll start using manual focus and wonder why you never used it in the first place. Soory to hear that the AF is on the fritz, but in a pro camera, you should never need it, and the EX1 IS a pro camera.
Bill Heslip December 22nd, 2007, 04:42 PM I hear what you're saying, Kit (and other contributors, like Evan, seem to agree that for pro users, poor autofocus isn't going to be a problem). If you don't mind, though, now I'm wondering how tricky it might be for me to get the hang of manual focus, and I'd love any advice. As I say, I'm a bit new to shooting - - I realize this perhaps means I should stick with the Z1, but I'd like to upgrade for the reasons I gave before (mostly: sick of tapes & want to get into editing faster; also, want to do less lighting).
I'd love know how hard it would be for me to learn to focus manually... I'd hate to start messing things up by shooting soft... Is the EX1 display so good (people are raving about it) that this is unlikely?
And here's my other question again (sorry if it sounds a bit silly) - - the fact that I mostly shoot with the lens zoomed out completely (if I want a tighter shot, I move closer) - - would this make it easier for me to stay in focus, in manual? (I realize that if I want to shoot someone walking towards the camera from 50 feet away, I'd have to be changing focus as they approach and pass me; but if I'm walking along beside them, if I stay zoomed out, I shouldn't have to adjust the focus, right?)
Thanks for your patience,
Malcolm
Malcolm, you seem to be a perfect candidate for the Sony wide-angle. Fewer critical focus issues (in the SD world anyway, can't vouch for HD, yet). Focus in manual and leave it, for the most part.
And I agree with fellow manual focus fans. Once you get the hang of it, you'll never go back.
Steven Thomas December 22nd, 2007, 05:34 PM Has anyone been able to confirm what I'm seeing with my camera?
I posted a simple test in my previous post. This way it will match what I'm seeing (if it does have the issue) one for one.
Like I said in my post. I don't normally use AF, but in the out of ordinary event I do, it would be nice if it at least some what worked.
I know it's a pro camera. That's why I bought it ;)
Charles Dasher December 22nd, 2007, 08:46 PM Hi Steven. I am a new to posting here but I have been following the forum for quite some time. I just set up and did the auto focus test as you suggested and I am getting similar results.
The focus gets close in 2-3 seconds but never truly locks in. I can see it both on the meter and on my monitor.
Coming from a DV background and always shooting run and gun style of action sports this concerns me as well. I welcome the ability to finally have a lens with true manual controls but in many situations a decent AF helps.
I waited a long time to upgrade from DV and I am hoping that this may be remedied through firmware. I also have to send my EX1 in for the vignette issue.
I am trying to keep my faith that I made a wise decision adopting early with the EX1.
Thanks
Dasher
Steven Thomas December 22nd, 2007, 08:57 PM Thanks Charles.
Yes, mine does get close, but just slightly pulses in and out of foccus.
It's odd because looking at the peaking I can see where it should stay locked and disable its servo, but if just keep moving back and forth.
Yes, apparently, this is what being an early adopter is all about.
I'm surprised these things were not noticed with the pre-production cam testers.
Again, I have used a lot of cameras and AF has only been just OK, some are very slow and fussy.
In this case, it doesn't really work. If nothing is moving, camera or image, it should be able to lock on good well lit high contrast objects.
Malcolm Hamilton December 22nd, 2007, 09:27 PM Malcolm, you seem to be a perfect candidate for the Sony wide-angle
Bill, I appreciate the encouragement... re the wide-angle - - do you mean a wide-angle lens I add on? If so, have contributors to this forum settled on a good one? (last time I checked, people were still wondering about thread-diameter issues).
Cheers,
Malcolm
Bob Grant December 22nd, 2007, 09:53 PM I think we need to put this into perspective. The EX1 is probably the most expensive camera with autofocus. Take the next step up and you don't get it at all, I don't think there's even a SD 1/2" camera with it.
Think it through, what do you want the AF to focus on. You can easily get shallow enough DOF where the most visible edge might not be where you want focus anyway, do you want to focus on the talents ears, eyes or nose. The first option will be the easiest for the AF to lock onto, the latter could be a problem and the eyes might be difficult too as it tries to find an edge. My DSC has a centre focus marker which is handy but hardly useful with moving images. Even more of a problem is with 16:9, it's quite common not to have the subject centre frame.
You can solve this to some extent with a rangefinder but without a scope / laser marker how do you know what it's measuring the distance to. Great if you're shooting set pieces, for gun and run largely useless.
I'm dead set hopeless at focussing and I wish there was a magic solution but I bought an EX1 knowing I'd need to hone my skills. I've mostly shot with a PD170 in the past or hired a good cameraman who could do the three ring dance while he danced around the talent.
The good news is if you're shooting exteriors you've probably got enough light so you can iris down and get enough DOF so focussing is less critical, as others have said staying wide will also help. One thing to check regularly is backfocus. The old zoom in, focus, zoom out trick will bring you unstuck if the backfocus is out.
Steven Thomas December 22nd, 2007, 10:03 PM Bob,
I thought I made it fairly clear that I don't normally use AF.
I'm not trying to make excuses for focusing a camera.
It's ovbvious AF can't read your mind on what you want in focus.
The thread was to understand why the EX1 AF is hunting even though the conditions are optimal. I just would like to know if the problem is across all cameras, or tied to just mine. I layed out a simple test for those who have the camera.
True about back focus. I've been nailed on that several times with my JVC HD100.
Ideally, you need to check it before any shoot and check it during the day, especially if there are temp changes.
Fortunately, no need to worry about back focus on the EX1, although, I hear there is a service menu option for adjustment in the factory or service.
Serena Steuart December 22nd, 2007, 10:15 PM Not fast. I was working through features last evening and auto focus was one. I'm used to giving the FX1 a jab for quick auto focus but on the EX I thought nothing was happening. So confirm slow and hunting, but not having noticed this thread I didn't quantify. Too slow to grab focus for run & gun but haven't checked how capably it tracks dynamic focus (ie. full auto focus). Peaking looks good for manual focus and so far I seem to be able to focus using the VF.
Steven Thomas December 22nd, 2007, 10:27 PM Thanks Serena.
When you get a chance, try the test I mentioned in this thread. I'd be interested if it shows the same symptoms.
Yes, the EX1 peaking really works great. The LCD is capable of making decent focus judgements. I was very surprised.
Bill Heslip December 22nd, 2007, 11:50 PM Bill, re the wide-angle - - do you mean a wide-angle lens I add on?
I was referring to the WA lens (add-on) made especially for the EX-1 (VLC-EX0877). There are or will soon be third party WA lenses available, although they will probably not be able to take advantage of the CA (chromatic aberration) reduction capability the Sony combo offers. In practice, no one yet knows how well this works.
Bob Grant December 23rd, 2007, 02:13 AM Steven,
sorry mate I thought we'd already determined that your camera was performing much the same as everyone else's.
I just did a pretty quick and sloppy test as I don't have a good set of sticks at hand and it's getting dark. However what I did notice was panning along the edge of a table at an angle so the distance to focus slowly increased the AF would suddenly loose the plot and go through a complete refocus.
First time I tried I had Macro on, turning it Off seemed to help but it still did the same dance just not quite as dramatically. I was panning quite slowly but hand held, perhaps someone with a good tripod and better setup should repeat this test but I'd say you certainly cannot rely on the AF to do a rack focus for you. The speed to find focus was around 2 seconds and I didn't notice any hunting once it'd found focus but that wasn't under good test conditions but certainly nothing unlike what you'd encounter under gun and run where you just have to get the shot and anything can happen.
My slightly better times might be because the camera was in 50i.
Steven Thomas December 23rd, 2007, 09:03 AM Thanks Bob,
This is why I am interested in the test I posted.
My camera when stationary and staring at high contrast objects in good light will nail focus for 1 second and then start to slightly move in and out
as if it did not find it. It should disable servo when it finds its peak.
While it's auto focusing, I can see where the peak is using the peaking function. I'm not sure why it does not disable servo once it rolls over the peak. I understand the camera should continue to adjust AF if the camera is moving across a different focus plane, but in this case it's stationary.
You're not seeing this, so this is starting to confirm my original thoughts that there's a problem with my camera.
Steve Mullen December 23rd, 2007, 09:33 AM "I suspect the slow autofocus is simply the price we have to pay for having a true mechanical lens - it's got to be much easier to make a fast, smooth and quiet autofocus when you don't have to have the lens elements coupled to gears meant to be turned by a large outer ring."
This is the reason I suspect. Most all the other AF cameras use an inner-focus system. Think of a lens carried within a speaker voice coil. Near instant response because there's almost no mass.
The question of the INDICATED hunting -- perhaps the VF read-out shows the sensor output. But, also perhaps, this signal is not being sent directly to the lens servo. Perhaps a "damped" version is sent to the servo. So, when you see the "hunting" do you see the mechanism moving? Or, do you see the focus change on a monitor?
Assuming it does hunt -- then the Push-to-Focus button is the key. I tend to hold it down for a second or two. The other is to use the Assist function to rapidly get close and manually find the final focus.
Steven Thomas December 23rd, 2007, 10:56 AM Steve,
On the EX1, I've never seen the outer focus ring move with the AF, regardless on how far focus was off. I'm assuming this is all done via an interval servo driven optic?
Well,
After more experimentation using all image modes, I did find that 1080 60i was the most stable. I was under the assumption, since the AF is time sampled based and needs a high frame rate that 720 60P would be sufficient.
Well, I was wrong! 60P hunts and rarely locks.
This is odd, when I tired the SAME tests yesterday, 1080 60i seemed also unstable; although, most of my testing was on 720 60P.
So I guess the bottom line is you can not use progressive, even at 60P when using AF mode?
From previous AF cameras I know this is true, but I sure thought 60P would of worked well enough.
Tom Roper June 4th, 2008, 01:06 PM ...but I want to confirm Steven Thomas' EX1 focus hunting behavior on my camera.
On a tripod, if I move the small switch to manual focus, the dof display is stable. If I thereafter press the AF button, the DOF display hunts continuously. I was expecting a one-time movement from this.
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