How good is the XL2 autofocus?

Bill Edmunds · February 21st, 2005, 02:33 PM

<<<-- Originally posted by Charlie Wilkinson : does anyone manually adjust both focus and zoom while panning/tilting for live events? That seems just a bit too demanding for me, but I'm just a beginner. Also, based on what Greg said about the single servo, sounds like I can't both focus and zoom at the same time anyhow, even manually.
>>>

I do it all the time with my Sony DSR250. Canon really made a lot of compromises with the XL2. I still don't know if I like it or not.

Jimmy McKenzie · February 21st, 2005, 02:49 PM

I am of two minds on this but my opinion is skewed toward manual operation.
First off, ask any camera operators at any sporting event about auto-focus and you will get the same HUH? look on their faces all the time. I recall chiming in on this topic a while back, but for hockey coverage you absolutely must be at the redline, use minimal zoom and manually focus on the middle of the crossbar at either net. Your fan reactions and cutaway content is done by eihther camera2 or during an icing call. If you don't have a safety cam setup like the one described above, your production will look like a focus nightmare. Just wait until safety netting is mandated ... It's here now and you can't fight it ... rinks demand manual control.

Charlie Wilkinson · February 21st, 2005, 05:52 PM

Ok, I went outside and played a little. It appears to me that the XL2 *does* continue to focus while zooming. I'm about as sure as I can be that I observed focus hunt (and lock) while in the middle of a medium-slow zoom. Reviewing the tape in slowmo confirms it. I can clearly see the subject (a cooperative conifer)going in and out of focus during the zoom.

No surprise, it also appears that lighting has a lot to do with it. Ample daylight yields better behavior than what I was seeing at the rink under the metal halide lamps.

Jimmy and Bill, thanks for your insights. I'm a newbie, my event du jour is figure skating and these are single camera shoots, so I don't think manual focus is a viable option at this point. My M.O. is basically "try to fill the frame with the skater whether right in front of me or at the other end of the rink." That keeps my hands pretty full with near constant slow to medium speed zooms and lots of panning. All that seems to work just fine with no AF problems. It's at the start and end of the skater's program when I try to zoom in rather quickly for some facial expression that I really run into issues. :-/

-cw-

Jimmy McKenzie · February 21st, 2005, 06:09 PM

Ok now I'm with you ... totally different than hockey ... I apologize for the assumtion.

Get yourself a nice reference monitor and do a setup at the rink during some experimentation time. If your rink is always the same, then you will be able to duplicate the results easily. Stop the lens up and perhaps a bit of gain until you are at a higher f number. This should increase your depth of field and give the latitude you need when the skater is moving toward /away from the lens. This is assuming that a follow spot is not used all that often on the skater. If you are near ice level this will be key. A lanc control will help here immensely as will a field monitor to watch your framing. Try manual settings and the odd bit of push af for a session. If that is unworkable, while still using the remote, you might be able to manipulate the focus ring as you move in for the headshot at the end of the performance. Practice will get you good at this so the out of focus blur time will be minimal.

Anthony Marotti · February 21st, 2005, 10:47 PM

<<<-- Originally posted by Jason Hakala : but i do know that the xl2 has 3 different auto focus speeds, low, medium, high.

jason -->>>

Hey Jason,

I don't know where you are getting this "3 different auto focus speeds" from, but I think you are mistaking it for the 3 constant "zoom speeds" that you are able to choose from.

As far as the XL series Auto-Focus and Image Stabilization, it is suppose to be some of the best in the industry, but I find my consumer Sony TRV 8 far superior in both regards. I do not like the Canon Auto-Focus or Image Stabilization at all and I don't use it, but I like other features of the camera, and I am a strictly manual shooter anyway :-)

Anthony Marotti · February 21st, 2005, 10:53 PM

<<<-- Originally posted by Bill Edmunds : <<<-- Originally posted by Charlie Wilkinson : does anyone manually adjust both focus and zoom while panning/tilting for live events?

Greg said about the single servo, sounds like I can't both focus and zoom at the same time anyhow, even manually.
>>>

You can't zoom and adjust focus at the same time with the Canon XL series, without a manual lens. That sucks, but when using the auto lenses, you just have to plan your shots a little more thoroughly :-)

A. J. deLange · February 22nd, 2005, 08:00 AM

Sounds like a job for the 16X manual. Good tripod, left hand on the focus ring, right fingers on the zoom rocker. Or better yet, remote controls for focus and zoom on the tripod handle.

Anthony Marotti · February 22nd, 2005, 09:35 AM

<<<-- Originally posted by Charlie Wilkinson : Ok, I went outside and played a little. It appears to me that the XL2 *does* continue to focus while zooming.

-cw- -->>>

Hello,

First, it is impossible to manually (or with remote control) focus and zoom at the same time.

As far as auto-focusing while zooming, well I only know what I have read here about that, but if it is true that there is only 1 servo for both functions, then that would be impossible without some mega monster incrementally differential shared transmission device.... I don't know about that :-)

But what I have observed is the following, which I would love a Canon rep to explain, and it may be what you are noticing, and think is focus hunting while zooming.

If you have auto-focus on and zoom fully in on a subject, you will notice on some cameras (my XL1 and XL2) that there is a slight pulsing... an electronic pulsing, which is consistent like it is generated by a timing cycle. It causes a slight amount of noise, or a shift in pixels, which looks like (or actually causes) auto-focus hunting.

Try it yourself with a very critical eye; set up a still subject, light it so that you have to use full open aperture (and maybe a little gain) zoom full in, turn on auto-focus, and don't touch the camera (use a big monitor if you like).

You will see a pulsating, or maybe auto-focus hunting...

Turn off autofocus.... you have a steady image now !!

I do not like the circuitry, or what ever else is causing this, which is one of the reasons I don't use auto-focus :-(

Greg Boston · February 22nd, 2005, 11:54 AM

Anthony,

You are most certainly taxing the AF with this camera setup. Full zoom and wide open aperture = DOF of literally a couple inches. Unless you have a solo object in the lense, it's going to get confused. I have done what you are talking about with a close-up shot outdoors in completely adequate lighting of a bouquet of flowers. Any miss in your framing will cause it to hunt for which flower bloom to lock onto.

There are 16 constant zoom speeds available and this setting also determines the speed of the zoom preset function. THE ONLY THREE SPEED selection on the XL-2 is for how fast you want the focus pre-set function to work. Fastest speed does a near instantaneous rack focus, while the slower one will allow you to watch the shot transistion from current to preset position. The Auto Focus has no speed adjustment. On the XL1s and XL-2, there is a 3 speed zoom selection for the top handle zoom rocker only. The XL-1 had only one speed on the handle rocker.

Page 40 of the XL-2 owner's manual points out operation of and limitations of the AF. If you don't actually own the XL-2, you can download the manual in PDF format from Canon's website.

-gb-

Anthony Marotti · February 22nd, 2005, 12:59 PM

Hello Greg,

I think we are mostly in agreement, except possibly when it comes to the AF scenario that I described.

Yes, if you tax a system, its weaknesses are revealed, I agree and that is why I did my tests that way. My subject was a solo object, in door, appropriately lit, and perfectly stationary.

I did witness this anomaly and it is real. It is also true with my XL1 as well as with my XL2, so as far as I can tell with limited testing, it is integral to the two camera systems and not just a malfunction of an individual camera.

As far as using the cameras (or any camera on my shoots) I always go manual for the style of shooting that I do. All of my shots are setup, lit, and measured for each scene, so I never need to gun-and-run.

It is not that much of an issue for me because of my shooting style, but I didn't expect the poor functionality, even from an inexpensive camera at this price-point. From what I had read, I expected Canon to be better than this.

I still love the camera and use it within its limitations though :-)

Greg Boston · February 22nd, 2005, 04:34 PM

Agreed Anthony. I posted, well...ok I lamented towards the top of this thread about the AF on the XL series. But, I can live with it or without it. In fact, when you keep your hand on a focus ring for a long time, it feels wierd to operate the camera in any other way.

I was hoping in my previous post to clear up some confusion in this thread about focus speeds and zoom speeds.

-gb-

Charlie Wilkinson · February 22nd, 2005, 11:04 PM

I've read that the LANC protocol doesn't allow for simultanious zoom and focus control. Seems like a glaring shortcoming, but I suspect LANC was designed for consumer level equipment. Had it been designed by/for the hard core folks, it probably would have more closely resembled the MIDI protocol, which can easily handle multiple commands at one time.

Internally, things get a little confusing. Using the rings, or focus ring and zoom rockers, I could not manually adjust focus and zoom at the same time. Period. It just doesn't work. Attempts to focus will be ignored in favor of zoom, which apparently has priority. However, I've reconfirmed at AF *does* hunt and lock while zooming. Try it yourself. Point at something close, start a slow zoom, then point at something farther away before you get to full telephoto.

So it seems that the problem is not a single servo, but a single control path from the external controls, or something like that.

Sounds like the best bet for my skating shoots (and limited skills) is full manual exposure mode, set the shutter to 1/60 and stop down the iris as much as possible. That should give me as much DoF as possible and lessen the AF issues. Of course (just to make things interesting) this runs counter to an apparent need to overexpose somewhat to counter all that brightly lit ice. Perhaps I can boost the gain somewhat to compensate, without introducing noticable noise?

One related question there... If iris, shutter *and* gain are all set manually, what happens to exposure as I zoom in? If it truly is pure manual exposure at that point, I would expect to get an underexposed shot as I zoom in. Assuming I don't have the option of constantly riding the iris, shutter, or gain, am I best off leaving gain set on auto and fixing shutter/iris for the whole shoot?

I can see now where I contributed to my own AF problems, because I did my previous shoot in "Av" mode and set the lens pretty much wide open (killing my DoF), to get that mild overexposure and bring out the colors in the skater's outfits. I also bumped AE shift up .5. At the time I was thinking that maintaining a fast shutter speed was important to reduce the "evils of motion blur." (sarcasm)

As I learn more about optics and video imaging in general, this camera in particular (I'm on page 93 :-) and how all the settings interact, it appears I may have other options for bringing the darker colors out of the muck, like setting a cine gamma curve, black stretch, tweaking the color gain, etc.

If any of that sounds particularly stupid, please feel free to let me know...

-cw-

Greg Boston · February 23rd, 2005, 08:23 AM

Charlie,

I think you are on the right path. But, next time run Av and set the iris to a higher value. Let the camera run shutter speed for you so it can maintain exposure. You might have to add some gain but the good news with the XL-2 is that adding gain isn't the quality penalty it used to be. The Noise Reduction feature in the image controls is meant specifically to counteract some of the noise induced from adding gain. The trade off is you might get some ghost trails of fast moving subjects in low light.

-gb-

Anthony Marotti · February 23rd, 2005, 08:25 AM

Hello Guys :-)

I think the Canon is a great camera for the money, but it does have its shortcomings.

One shortcoming is the manual, doesn't really explain too much. I guess they couldn't elaborate after spending so much money on providing me with a zillion versions of languages that I don't speak...

3rd Party Manual might be nice :-0

Marty Hudzik · February 23rd, 2005, 10:49 AM

<<<-- Originally posted by Charlie Wilkinson : One related question there... If iris, shutter *and* gain are all set manually, what happens to exposure as I zoom in? If it truly is pure manual exposure at that point, I would expect to get an underexposed shot as I zoom in. Assuming I don't have the option of constantly riding the iris, shutter, or gain, am I best off leaving gain set on auto and fixing shutter/iris for the whole shoot?

cw- -->>>

I wouldn't recommend setting the gain on auto as it always seems to crank up to +12 even when it really isn't necessary. I would try using +6 at the most. You will see very little noise except in the darkest areas of your screen.

Good luck!

February 21st, 2005, 05:52 PM	#18
Charlie Wilkinson Regular Crew Join Date: Feb 2005 Location: Annapolis, MD Posts: 53	Ok, I went outside and played a little. It appears to me that the XL2 does continue to focus while zooming. I'm about as sure as I can be that I observed focus hunt (and lock) while in the middle of a medium-slow zoom. Reviewing the tape in slowmo confirms it. I can clearly see the subject (a cooperative conifer)going in and out of focus during the zoom. No surprise, it also appears that lighting has a lot to do with it. Ample daylight yields better behavior than what I was seeing at the rink under the metal halide lamps. Jimmy and Bill, thanks for your insights. I'm a newbie, my event du jour is figure skating and these are single camera shoots, so I don't think manual focus is a viable option at this point. My M.O. is basically "try to fill the frame with the skater whether right in front of me or at the other end of the rink." That keeps my hands pretty full with near constant slow to medium speed zooms and lots of panning. All that seems to work just fine with no AF problems. It's at the start and end of the skater's program when I try to zoom in rather quickly for some facial expression that I really run into issues. :-/ -cw- __________________ Charlie Wilkinson Full-time SysAdmin/Programmer Part-time Videographer wanna-be

February 21st, 2005, 06:09 PM	#19
Jimmy McKenzie Major Player Join Date: Jan 2004 Location: Waterloo Ontario Posts: 721	figure skating eh.. Ok now I'm with you ... totally different than hockey ... I apologize for the assumtion. Get yourself a nice reference monitor and do a setup at the rink during some experimentation time. If your rink is always the same, then you will be able to duplicate the results easily. Stop the lens up and perhaps a bit of gain until you are at a higher f number. This should increase your depth of field and give the latitude you need when the skater is moving toward /away from the lens. This is assuming that a follow spot is not used all that often on the skater. If you are near ice level this will be key. A lanc control will help here immensely as will a field monitor to watch your framing. Try manual settings and the odd bit of push af for a session. If that is unworkable, while still using the remote, you might be able to manipulate the focus ring as you move in for the headshot at the end of the performance. Practice will get you good at this so the out of focus blur time will be minimal.

February 21st, 2005, 10:47 PM	#20
Anthony Marotti Major Player Join Date: Feb 2005 Location: Rochester, NY Posts: 263	<<<-- Originally posted by Jason Hakala : but i do know that the xl2 has 3 different auto focus speeds, low, medium, high. jason -->>> Hey Jason, I don't know where you are getting this "3 different auto focus speeds" from, but I think you are mistaking it for the 3 constant "zoom speeds" that you are able to choose from. As far as the XL series Auto-Focus and Image Stabilization, it is suppose to be some of the best in the industry, but I find my consumer Sony TRV 8 far superior in both regards. I do not like the Canon Auto-Focus or Image Stabilization at all and I don't use it, but I like other features of the camera, and I am a strictly manual shooter anyway :-) __________________ AM

February 21st, 2005, 10:53 PM	#21
Anthony Marotti Major Player Join Date: Feb 2005 Location: Rochester, NY Posts: 263	<<<-- Originally posted by Bill Edmunds : <<<-- Originally posted by Charlie Wilkinson : does anyone manually adjust both focus and zoom while panning/tilting for live events? Greg said about the single servo, sounds like I can't both focus and zoom at the same time anyhow, even manually. >>> You can't zoom and adjust focus at the same time with the Canon XL series, without a manual lens. That sucks, but when using the auto lenses, you just have to plan your shots a little more thoroughly :-) __________________ AM

February 22nd, 2005, 08:00 AM	#22
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Figure Skating... Sounds like a job for the 16X manual. Good tripod, left hand on the focus ring, right fingers on the zoom rocker. Or better yet, remote controls for focus and zoom on the tripod handle.

February 21st, 2005, 02:33 PM	#16
Bill Edmunds Major Player Join Date: Aug 2003 Location: Conway, NH Posts: 574	<<<-- Originally posted by Charlie Wilkinson : does anyone manually adjust both focus and zoom while panning/tilting for live events? That seems just a bit too demanding for me, but I'm just a beginner. Also, based on what Greg said about the single servo, sounds like I can't both focus and zoom at the same time anyhow, even manually. >>> I do it all the time with my Sony DSR250. Canon really made a lot of compromises with the XL2. I still don't know if I like it or not.

February 21st, 2005, 02:49 PM	#17
Jimmy McKenzie Major Player Join Date: Jan 2004 Location: Waterloo Ontario Posts: 721	I am of two minds on this but my opinion is skewed toward manual operation. First off, ask any camera operators at any sporting event about auto-focus and you will get the same HUH? look on their faces all the time. I recall chiming in on this topic a while back, but for hockey coverage you absolutely must be at the redline, use minimal zoom and manually focus on the middle of the crossbar at either net. Your fan reactions and cutaway content is done by eihther camera2 or during an icing call. If you don't have a safety cam setup like the one described above, your production will look like a focus nightmare. Just wait until safety netting is mandated ... It's here now and you can't fight it ... rinks demand manual control.

February 22nd, 2005, 09:35 AM	#23
Anthony Marotti Major Player Join Date: Feb 2005 Location: Rochester, NY Posts: 263	<<<-- Originally posted by Charlie Wilkinson : Ok, I went outside and played a little. It appears to me that the XL2 does continue to focus while zooming. -cw- -->>> Hello, First, it is impossible to manually (or with remote control) focus and zoom at the same time. As far as auto-focusing while zooming, well I only know what I have read here about that, but if it is true that there is only 1 servo for both functions, then that would be impossible without some mega monster incrementally differential shared transmission device.... I don't know about that :-) But what I have observed is the following, which I would love a Canon rep to explain, and it may be what you are noticing, and think is focus hunting while zooming. If you have auto-focus on and zoom fully in on a subject, you will notice on some cameras (my XL1 and XL2) that there is a slight pulsing... an electronic pulsing, which is consistent like it is generated by a timing cycle. It causes a slight amount of noise, or a shift in pixels, which looks like (or actually causes) auto-focus hunting. Try it yourself with a very critical eye; set up a still subject, light it so that you have to use full open aperture (and maybe a little gain) zoom full in, turn on auto-focus, and don't touch the camera (use a big monitor if you like). You will see a pulsating, or maybe auto-focus hunting... Turn off autofocus.... you have a steady image now !! I do not like the circuitry, or what ever else is causing this, which is one of the reasons I don't use auto-focus :-( __________________ AM

February 22nd, 2005, 11:54 AM	#24
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	Anthony, You are most certainly taxing the AF with this camera setup. Full zoom and wide open aperture = DOF of literally a couple inches. Unless you have a solo object in the lense, it's going to get confused. I have done what you are talking about with a close-up shot outdoors in completely adequate lighting of a bouquet of flowers. Any miss in your framing will cause it to hunt for which flower bloom to lock onto. There are 16 constant zoom speeds available and this setting also determines the speed of the zoom preset function. THE ONLY THREE SPEED selection on the XL-2 is for how fast you want the focus pre-set function to work. Fastest speed does a near instantaneous rack focus, while the slower one will allow you to watch the shot transistion from current to preset position. The Auto Focus has no speed adjustment. On the XL1s and XL-2, there is a 3 speed zoom selection for the top handle zoom rocker only. The XL-1 had only one speed on the handle rocker. Page 40 of the XL-2 owner's manual points out operation of and limitations of the AF. If you don't actually own the XL-2, you can download the manual in PDF format from Canon's website. -gb-

February 22nd, 2005, 12:59 PM	#25
Anthony Marotti Major Player Join Date: Feb 2005 Location: Rochester, NY Posts: 263	Hello Greg, I think we are mostly in agreement, except possibly when it comes to the AF scenario that I described. Yes, if you tax a system, its weaknesses are revealed, I agree and that is why I did my tests that way. My subject was a solo object, in door, appropriately lit, and perfectly stationary. I did witness this anomaly and it is real. It is also true with my XL1 as well as with my XL2, so as far as I can tell with limited testing, it is integral to the two camera systems and not just a malfunction of an individual camera. As far as using the cameras (or any camera on my shoots) I always go manual for the style of shooting that I do. All of my shots are setup, lit, and measured for each scene, so I never need to gun-and-run. It is not that much of an issue for me because of my shooting style, but I didn't expect the poor functionality, even from an inexpensive camera at this price-point. From what I had read, I expected Canon to be better than this. I still love the camera and use it within its limitations though :-) __________________ AM

February 22nd, 2005, 04:34 PM	#26
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	Agreed Anthony. I posted, well...ok I lamented towards the top of this thread about the AF on the XL series. But, I can live with it or without it. In fact, when you keep your hand on a focus ring for a long time, it feels wierd to operate the camera in any other way. I was hoping in my previous post to clear up some confusion in this thread about focus speeds and zoom speeds. -gb-

February 22nd, 2005, 11:04 PM	#27
Charlie Wilkinson Regular Crew Join Date: Feb 2005 Location: Annapolis, MD Posts: 53	I've read that the LANC protocol doesn't allow for simultanious zoom and focus control. Seems like a glaring shortcoming, but I suspect LANC was designed for consumer level equipment. Had it been designed by/for the hard core folks, it probably would have more closely resembled the MIDI protocol, which can easily handle multiple commands at one time. Internally, things get a little confusing. Using the rings, or focus ring and zoom rockers, I could not manually adjust focus and zoom at the same time. Period. It just doesn't work. Attempts to focus will be ignored in favor of zoom, which apparently has priority. However, I've reconfirmed at AF does hunt and lock while zooming. Try it yourself. Point at something close, start a slow zoom, then point at something farther away before you get to full telephoto. So it seems that the problem is not a single servo, but a single control path from the external controls, or something like that. Sounds like the best bet for my skating shoots (and limited skills) is full manual exposure mode, set the shutter to 1/60 and stop down the iris as much as possible. That should give me as much DoF as possible and lessen the AF issues. Of course (just to make things interesting) this runs counter to an apparent need to overexpose somewhat to counter all that brightly lit ice. Perhaps I can boost the gain somewhat to compensate, without introducing noticable noise? One related question there... If iris, shutter and gain are all set manually, what happens to exposure as I zoom in? If it truly is pure manual exposure at that point, I would expect to get an underexposed shot as I zoom in. Assuming I don't have the option of constantly riding the iris, shutter, or gain, am I best off leaving gain set on auto and fixing shutter/iris for the whole shoot? I can see now where I contributed to my own AF problems, because I did my previous shoot in "Av" mode and set the lens pretty much wide open (killing my DoF), to get that mild overexposure and bring out the colors in the skater's outfits. I also bumped AE shift up .5. At the time I was thinking that maintaining a fast shutter speed was important to reduce the "evils of motion blur." (sarcasm) As I learn more about optics and video imaging in general, this camera in particular (I'm on page 93 :-) and how all the settings interact, it appears I may have other options for bringing the darker colors out of the muck, like setting a cine gamma curve, black stretch, tweaking the color gain, etc. If any of that sounds particularly stupid, please feel free to let me know... -cw- __________________ Charlie Wilkinson Full-time SysAdmin/Programmer Part-time Videographer wanna-be

February 23rd, 2005, 08:23 AM	#28
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	Charlie, I think you are on the right path. But, next time run Av and set the iris to a higher value. Let the camera run shutter speed for you so it can maintain exposure. You might have to add some gain but the good news with the XL-2 is that adding gain isn't the quality penalty it used to be. The Noise Reduction feature in the image controls is meant specifically to counteract some of the noise induced from adding gain. The trade off is you might get some ghost trails of fast moving subjects in low light. -gb-

February 23rd, 2005, 08:25 AM	#29
Anthony Marotti Major Player Join Date: Feb 2005 Location: Rochester, NY Posts: 263	Hello Guys :-) I think the Canon is a great camera for the money, but it does have its shortcomings. One shortcoming is the manual, doesn't really explain too much. I guess they couldn't elaborate after spending so much money on providing me with a zillion versions of languages that I don't speak... 3rd Party Manual might be nice :-0 __________________ AM

February 23rd, 2005, 10:49 AM	#30
Marty Hudzik Trustee Join Date: Jul 2004 Location: Canton, Ohio Posts: 1,771	<<<-- Originally posted by Charlie Wilkinson : One related question there... If iris, shutter and gain are all set manually, what happens to exposure as I zoom in? If it truly is pure manual exposure at that point, I would expect to get an underexposed shot as I zoom in. Assuming I don't have the option of constantly riding the iris, shutter, or gain, am I best off leaving gain set on auto and fixing shutter/iris for the whole shoot? cw- -->>> I wouldn't recommend setting the gain on auto as it always seems to crank up to +12 even when it really isn't necessary. I would try using +6 at the most. You will see very little noise except in the darkest areas of your screen. Good luck!