As my eyes grow less precise, I find myself needing autofocus more than I used to. My Sony DSR250 has lightning fast, very solid autofocus. How is the XL2's autofocus compared to the DSR250/PD170, et al? And, yes, I am fully aware that manual focus is always preferable.

I think the auto-focus on the XL2 is one of the things that has taken a backwards step from previous models. Even my old GL1 performed better. The focus tends to shift back and forth between foreground and background, and zooming any faster than at a snails pace will make the focus go wild. I find myself having to use the focus ring VERY often to correct auto-focus problems. I love my XL2 in every other aspect, but I think Canon has done much better in the past with this feature. Hope this helps.

i dunno how the xl2 matches up with the dsr-250 in auto focus speed, but i do know that the xl2 has 3 different auto focus speeds, low, medium, high.

which is pretty handy because sometimes the focus is too fast and leaves the main subject, in this case you would swith to medium or low.


jason

<<<-- Originally posted by Jason Hakala : i dunno how the xl2 matches up with the dsr-250 in auto focus speed, but i do know that the xl2 has 3 different auto focus speeds, low, medium, high.

-->>>

Jason, are you sure about this? I don't see any difference in focus speed when I change this setting, and the way I interpret the manual, the setting only refers to the speed when changing to the preset focus, not to normal autofocus speed.

Richard

I'll disagree with brent on this one. The xl2 focus has been tuned to a slower (so it won't match the lightning fast dsr 250), but more steady parameter as compared to the xl1s. It rarely hunts in comparable situations, and is on par with the GL2 in terms of speed and steadiness. I've found its focusing ability in low light to be markedly improved over the xl1s (although that is essentially starting from zero). And in answer to bill's question, it has been improved also by the inclusion of the focus presets.

Barry

I'd say, this autofocus rocks!

I shoot a lot of fashion shows, now with the XL2. Always with autofocus. Honesty forces me to say that most of the times, these shows are lit properly, so you can shoot at 0 dB gain, at 5.6. I rarely see the focus hunt or loose it.

richard im pretty sure thats what it does. it controls the hunt speed of the focus, i know this because of one of the reviews on the xl2 in videomaker was talking about it, and they got the info from a canon rep. ive only had my xl2 for about a week and haven't really tested it out to much but from what ive tried it worked.

jason

Also be advised that autofocus is going to react slower in 30p and even slower still in 24p. The slower the frame rate, the slower the autofocus can update itself.

<<<-- Originally posted by Jason Hakala : richard im pretty sure thats what it does. it controls the hunt speed of the focus, i know this because of one of the reviews on the xl2 in videomaker was talking about it, and they got the info from a canon rep. ive only had my xl2 for about a week and haven't really tested it out to much but from what ive tried it worked.

jason -->>>

Hi Jason. I think I saw that review too, but I don't see that setting make any difference at all to the autofocus speed on my camera. It does work fine on the return-to-preset focus speed however, so it's not just that a switch is broken on my cam. How much difference are you seeing between the slowest and faster settings?

Regarding the autofocus generally, I would agree with Jan that if you have a reasonable depth of field the autofocus is pretty good. I think it is hunting most of the time, but you only really notice it when you have the iris open wide and the depth of field correspondingly tight. Of course we should use manual when we can, but sometimes you just have to get the shot and when it's a moving target, autofocus is very useful.

Richard

I've noticed with my new XL2 that autofocus has issues. I got this camera to use for shooting in dynamic settings, lots of moving targets -- sporting events and whatnot. So this is a make or break problem for me, not just an annoyance I can work around. I've noticed that zooming in tight on somone's face often results in a blurry image. Sometimes it corrects itself quickly, sometimes not. If I zoom in on two people talking (and I mean upper torsos nearly filling the frame with a small gap in between), this camera will often try to focus on the background behind the two subjects! This is at an indoor ice rink, where I would expect the lighting to be adequate for good AF function. I'm shooting plain vanilla, 60i, 4:3.

In the interest of full disclosure, I'm new to this level of video camera. I never had this kind of problem with my trusty old Sony TRV-30. Its AF always "just worked" except in low light. It was a rude shock to suddenly start having AF problems with an "overengineered" camera costing three times as much.

So, is there likely a problem with my specific XL2, a general shortcoming for this model, or am I just doing something wrong?

Any clues greatly appreciated...

-cw-

Charlie,

I think there are a couple of issues leading to your problems that are design related, and not necessarily "flaws" in the xl2.

The first, and most important as it relates also to the second is that the Xl2 (and gl2) are the only cameras on the market with a true 20x optical zoom, as compared to the trv-30's 10x zoom. This extra length of zoom requires a much greater focus shift from foreground to background (One one of the differences you've probably noticed is that when you are zoomed all the way in with the xl2, that there is actually a noticeable blurring of the background--or foreground in your case!--, where as the trv-30 almost everything is sharp all the time under good lighting). A good way to test this is to limit the xl2 to half of its zoom range (slider bar at top of viewfinder). You'll find that at this zoom level most of the problems disappear (as does the depth of field). As you approach 20x zoom, the focus "travel" or adjustment increases exponentially, even between objects that are only feet or inches apart.

The second issue is related to you description of two people talking with a gap in between them. (remember anything related to this issue is made more of a problem by the 20x zoom). The camera is doing exactly as its told if you place that gap in the center of the frame. The camera doesn't know what you want to focus on, so it designates an area at the center of the frame as its focus area. This is a classic situation where almost all autofocus systems fail. (Canon does produce a nice indexed focus system on its still cameras, and I do wonder why it isn't incorporated in the video cameras).

Regarding the zooming in to a face, with the camera taking a second to correct the focus. This is also by design, although the xl2 may do it slower than the smaller lens of the trv-30 (remember the 20x)...the xl2 is not capable of zooming and focusing at the same time (I'm not sure if any camera is) so once you finish your zoom, the autofocus takes over to correct any mis-focus from when the camera was at its wider zoom. A typical way of handling this issue is to prefocus on the face (manual zoom) and then pull wide and rezoom to a perfect shot.

All autofocus systems will show the problems you've listed, given the right circumstances. The trv-30 will show it less than the xl2 due to it's shorter lens. Additionally the xl2's autofocus is tuned a little slower than other systems to eliminate the hunting that can happen (again mostly at longer zoom ratios) especially in low light.

Hope this helps.

Barry

Barry,
Thanks very much for your thoughtful response. What you're saying about the 20x zoom makes sense, but I don't think it completely applies. Even taking all that into account, I'd still have to characterize this XL2's AF performance as "weak, a little slow and too small of a spot." I understand it's center weighted, but this is nuts. (And I agree wholeheartedly about the indexed focus.)

I think part of the problem is that we're in the realm of subjective judgements. And I've been spoiled by the apparently very good AF on the TRV-30. Also, you have a better understanding of the optical miracle that Canon has wrought here and will be perhaps a little more forgiving of quirks, while I (being a stubborn, demanding SOB new to high-end cameras), expect my design miracles without shortcomings. i.e., "They should have designed an AF that can handle a 20x lens, period."

Regardless, your suggestion of limiting my zooming to 10x and observing the results is a good one and I'm going to give it a try. This also makes me wonder if a related contributor to my problem is "zoom fever" as a result of having a new toy with this capability. In other words, the problem may subside somewhat as I get more seasoned and learn to use zoom more sparingly? Right now I feel compelled to fill the frame with my subjects, near or far.

There are a lot of things I really like about this camera and would rather not have to go through the hassle and disruption of hunting down something else.

Just curious... If someone came to you and said "What's the best sub-$5000 camera for shooting live sporting events?", what would you answer? Anyone else care to take a shot at that one?

Thanks again,
Charlie

"They should have designed an AF that can handle a 20x lens, period."

I think they have... it's just that "instantaneous, perfect focus" is not really a reality with long lenses. I've used 600mm still camera lenses, and they can often be fooled by foreground - background issues, and because the focus shifts can be several inches at the lens, these goofs stick out a lot more than a short lens that is moving 1/8" or less during a focus adjustment.

Yes the xl2 is a little slower than I'd like...although I'd agree also that I prefer this to the hunting that can happen with a faster focusing situation like the xl1s with the 16x isII.

Anyway, good luck with it. Hopefully it will start to feel normal to you in short order.

Barry

I have to admit that I was less than enthusiastic about the auto focus performance on my XL-2 with stock 20x lense. But, I tend to run in manual so that I have the exposure meter to work with and I will say that most focus hunting I have seen is with less than optimal exposure. I would like to see Canon adopt a hybrid auto focus which has been done with some Kodak and Sony still cameras. Those things can focus in near total darkness.

Barry, the more expensive lenses can zoom and focus at the same time because they have separate servos for each. For cost reasons, Canon has elected to continue using a shared servo approach in the XL auto lense.

Another point about the Canon's auto focus is that it NEEDS to see good contrast in the scene and vertical lines if possible.

One reason that some of the smaller cameras may focus better is due to the fact that they shoot an infra-red beam and use it to focus with. IIRC, the Canon uses the image on the CCD's which is why it needs contrast and vertical lines to work with. Naturally, the IR approach is going to perform better in low light scenarios.

And finally, the three speeds on the Canon for focus are for the focus preset only. AF works at one speed forj 60i, slower at 30p and slower yet at 24p as Chris stated. I believe it is the Sony HDV that has the different speed settings for the AF which I think are labeled High, Medium, and Low.

regards,

-gb-

Thanks Barry and Greg. Shared servo... Ack!! Sounds like I need to save up my pennies for a *really* expensive camera. You think $50k oughta do it, or am I looking at more like $100k? ;-)

Seriously, I'm feeling rather humbled right now. I knew in advance that I'd probably be doing mostly live sports. I also suspected that would be a rather demanding task (though I figured more so on me than the camera). As far as selecting a camera went, I did my research and knew the XL2 gets good reviews and is regarded as top of the heap by many owners. I did not however go the extra step and research whether the XL2 was the best fit for the kind of work I'm doing. ...and perhaps it *is* the best fit for its price range and I really do need to save my pennies. And I've only done one event with this thing so far. Maybe I just need a little more time to get acquainted.
(Further reassurance welcomed!)

Curious, 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.

-cw-

<<<-- 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.

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.

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-

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.

<<<-- 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 :-)

<<<-- 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 :-)

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.

<<<-- 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 :-(

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-

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 :-)

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-

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,

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-

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

<<<-- 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!

Charlie,

Have you tried using the standard technique of zooming in to max telephoto, and then set focus? You may then zoom out and your subject will remain in focus without any further adjustment. Of course this assumes leaving the focus control in manual.

The minute the skater moves from the point of "critical focus" as you have described, the shot is now out of focus. Since skaters are shot close to ice level, the movement is just too much to maintain a rack focus.

Yup, what Jimmie said. Skaters have historically been very uncooperative about skating only on my preset focus line. ;-)

So to recap, sounds like my best bet is Av mode with the lens closed down as far as possible and the gain set on +6.

Anyone have much experience playing with black stretch?

-cw-