XL1 / XL1S focus hunting backfocus problems

[Ken Tanaka]

Steve,
I haven't had much of a chance to shoot wildlife with my XL1 or XL1s (not even a rave party <g>) but I understand your problem with critical focus drift, especially with a zoomed-out AF situation.

Mike's "bet" is likely on the mark. I use the 14x full manual lens for all standard work where focus is critical. It's still available for approx. $1000. I haven't tried the newer 16x manual lens (with servo-zoom option).

I also use the Fujinon B&W viewfinder for all shoots where focus / d.o.f. will be critical. Yes, it's a rather expensive bugger and can suck power like an ex-Enron exec but the increased resolution over the color lcd vf makes a very significant difference.

I wouldn't give up on your XL1s for wildlife shooting yet. Being in NYC perhaps you can rent the manual lens and b&w head to take them out for a test shoot to see if they make a difference in your work.

[John Klein]

I'm curious.

Are you bumping the preset sharpness up a ways?

I feel that "out of the box," the XL1S is great for interviews (soft), but once you're at +3 or so, things get pretty nice. If you are not adding any gain, I think you can bump it up pretty high without too many problems.

The same goes for preset color saturation. If you feel it's muted, try adding a little extra.

FYI I use the longer end of the zoom as well as with the 1.6x. I generally use manual focus and hit the AF now button. This may or may not be your best bet for wildlife, as AF will hunt.

[John Locke]

<<...suck power like an ex-Enron exec...>>

LOL!

[Chris Hurd]

For normal event videography, the EOS adapter is not a viable alternative to the standard 16x lens. This is because the EOS adapter multiplies the focal length of any EOS lens by a factor of 7.2. There's no way you can get wide with it. Even the widest EOS lens becomes extreme telephoto on the XL1/XL1S. The EOS adapter is best suited for wildlife videography. You'll need an IS lens (optical image stabilization) for this purpose.

If you're not happy with the standard 16x lens, the next best option is the new 16x manual lens, especially when you consider that remote zoom and focus control, so critical to good videography, is readily available for this lens (and not for the EOS option). Hope this helps,

[Henry Czuprinski]

I seem to remember reading in Canon literature that the new manual lens works with the extender- 26x or so I'd guess. Worth checking out.

<<<I also use the Fujinon B&W viewfinder for all shoots where focus / d.o.f. will be critical. Yes, it's a rather expensive bugger and can suck power like an ex-Enron exec but the increased resolution over the color lcd vf makes a very significant difference.>>>

Hi Ken,

Which batteries do you use with B&W viewfinder, and how long do they last? I realize that auto zoom and auto-focus will affect battery life, as well. . . just trying to get a general idea about VF. I'm thinking about getting XL1S w/ B&W VF and am wondering what I'd have to do about batteries.

Thanks,
Kat

[Ken Tanaka]

Kat,

I've been using the Canon BP945 high-capacity batteris with pretty good luck. I have the dual battery holder but haven't really used it yet. I don't think I've run one completely dry yet, but I've come close. In general I can (conservatively) count on at least 2.25 hrs. when using the 14x manual lens (which consumes virtually no power, since it has no power zoom or iris servos) and perhaps 2 hrs when using the 16x or 3x lenses.

One thing you should note about the b&w viewfinder is that it confounds the battery monitor/meter. For some reason because the b&w head connects to the cam's battery slot you won't see a "remaining capacity" indicator in the viewfinder until the battery is nearly drained, if at all. This is a documented "feature" of the b&w head but I really think it's too bad. This is something that is not really mentioned very often during talk of the b&w vf.

I have not ventured into any of the other batteries (such as the Lenmar) yet but am planning to do so.

Hi Ken,

That's encouraging. I was afraid I'd have to use the dual-battery charger, which seems so bulky. Thanks for the warning about lack of VF info about state of battery. Will have to keep an eye on my watch!

Best,
Kat

A partner I work with frequently purchased an XL1 about a year ago. He comes from a still photography background and is meticulous and critical in approach. He chose the XL1 because of its aesthetics and ergonomics. It’s much more a “photographers tool” than the VX1000. I do some of the shooting, and all the post on our projects. We’ve shot hundreds of hours and completed many projects over the past year and the issue of “soft focus” never really came up. The footage looked great. We shoot a lot of industrial/corporate work for the construction industry – mostly exterior job sites but with some indoor venues as well. I had heard of “focus problems” with the camera but assumed it referred only to the focus “jump” – annoying but not insurmountable.

We recently started work on a project that involves taping interviews with hundreds of individuals in one remote location, We created a “limbo” black background and use basic 3 point lighting – key, fill, and back – with 1K Ianero’s. We shoot manual exposure and focus and are about 6-8 feet from the subject with Canon’s 16X auto lens. Shot composition varies from MS to CU. Suddenly the “soft focus” issue was huge. We weren’t satisfied with the image when zoomed out to a MS. The image is SOFT!. Immediately purchased the Canon 16X manual and used for the first time a couple of days ago. It seems to have solved the problem but will reserve judgment until I take material into post and observe on Sony broadcast monitor. So how come we didn’t notice till now? I’m not sure but think it must have to do with nature of shot – the limbo background forces attention to the subject. I looked back at some older footage – with a more critical eye – and thought it too might have been a little soft but not so obviously.
Read Chris Hurd’s article concerning differences of opinion and this may shed a little light.

Regarding my experience with back focus. I think it was a more prevalent issue in the “old days” – I’ve been at this for over 25 years. Used to do an in-studio shoot with massive Ampex 1000? 3 tube plumbicon cameras. Neville, the engineer, used to wheel them to an outside door (studio wasn’t large enough to achieve “infinity focus” ) and use a tree about ½ mile away for back focus adjustment. Zoom in tight on the tree branches, zoom to widest shot and then adjust the POSITION OF THE YOKE holding the 3 tubes. (moving it closer or further from the last piece of glass in the lens) One article on this site – written by Per Sverre Wold-Hanson – refers to “professional” lenses provision for back focus adjustment. The Canon16X manual is the first lens I’ve encountered that has such a provision. I’ve always assumed back focus was always achieved as on my old Ampex cameras. I’ve also assumed that the move to CCD pickup devices (vs. tubes) has virtually eliminated back focus adjustments. The older systems were much more susceptible to environmental, manufacturing, etc. fluctuations.

I would find it hard to believe that this issue is related to back focus. Even harder to believe that it affects many, but not all, XL1’s. If it’s a problem with back focus, retool at the factory and adjust the distance from back glass to pickup chips. If it’s not back focus what is it? The Canon 16X automatic lens has phenomenal stabilization capabilities. As I understand it, the lens incorporates some kind of “floating” element. “Floating element”….”soft image”……hmmmmmm

[Peter Koller]

The same occured to me yesterday. Even the setup is similiar. I am shooting a dialogue on a table in a living room with a blank and bright wall as background. I used the rooms TV set as control monitor (a completely new 82cm 16:9 Philips) via the S-VHS connection while I tried to set up my lights (see thread "lighting struggle"). The camera itself was on a tripod and never moved.

What happened was:

I turned on the camera in GREEN MODE (full auto) and the picture was perfectly sharp and whitebalanced. We were surprised that it looked that good on the big screen even with the lights in the wrong places.

Switched to M (full manual mode) and to manual focus and manually whitebalanced:

The whitebalance:
The image got really yellowish compared to the pure white I got with auto-balancing. I don´t think I made a mistake when I balanced it manually: I used a sheet of paper (ca. 40x50cm), zoomed in at it so it filled frame and pushed the balancing button.
I switched to Auto-balancing again, because the quality was much better than one I got from manual.

Manual focus:
The image got soft (at the border between being super-super-soft and out of focus) when I turned the mode-wheel. Does the lens do anything when I switch modes and don´t move anything on the set? I pressed the push-AF button, but the focus did not get better. It did not change at all. Then I had someone sit at that table and hold a big piece of cardboard with lots of vertical lines on it. Pressed the button again. No change. Still out of focus. Then I turned the servo-wheel on the lens itself. This worked. The image turned crystal clear. The problem is just that I had to judge the focus by eye. Without distance markings on the lens this is a little of a lottery to set it rightly.

Normally I would think, something in the frame distracts the camera from setting it perfectly, like mixed colors or it can´t get a grip onto something to focus on. But it works perfectly in GREEN MODE. How come it loses all in manual mode?

Wait, this comes to my mind right now... Does frame mode and 16:9 work in GREEN MODE or are they ignored? I am not sure now. I had both of them activated, maybe those come into play when I switch to manual mode and mess things up?

Which settings did you use, Sweeper?

Cheers,

[Chris Hurd]

Peter -- Frame Movie mode and 16:9 are not available in Green Box (easy recording) mode.

"sweeper7" -- the Canon 16x auto lens, like all modern vari-focal automatic lenses with rear-focus groups, is completely controlled by software. There are some cameras out there with the old original software and there are others with various levels of software updates. That's why some cameras have that problem and some don't. It has always been an electronic issue, not a mechanical one.

All broadcast professional video zoom lenses I've ever had my hands on have a provision for adjusting back focus, whether they're Canon or Fujinon. Hope this helps,

[Don Palomaki]

With the Canon 16x standard automatic/servo lens the backfocus is set by storing a setting in memory in the camcorder. It is part of the service/setup procedure performed at test bench (not a user adjustment). Swapping lenses among differnt camcorder bodies might result in a mismatch of backfocus.

The green box setting is auto everything.

The image stabilixation is accomplished with a variable angle prism (VAP), which is locate just behind the protective front piece of glass. The VAP amoutns to two parallel pieces of optical glass with a transparent liquid between them.There is a mechanism the shifts the angle of the glass slightly to forma prism effect thus compensating for motion.

[Charles Papert]

Reading "sweeper 7"'s post about backfocus in the Plumbicon days, I found issue with part of his old engineer Neville's technique that is applicable to users of the Canon manual lenses (14x and 16x). As with front focus, back focus becomes more critical with the lens wide open. Thus the adjustment should preferably be done inside in a lower light level, not outside, to achieve the most accurate results. You will need a large space to do this (presumably Neville had a studio at his disposal!) with the camera at one end and the target at the other, but in my opinion, it's better to cheat the distance part of the equation than to perform the task at f11. That said, judicious use of the ND filters, shutter setting and -3db gain setting outside could be use to bring the f-stop towards a workable place (f 2.8 and under).

<<<-- Originally posted by Chris Hurd : Peter -- Frame Movie mode and 16:9 are not available in Green Box (easy recording) mode.

"sweeper7" -- the Canon 16x auto lens, like all modern vari-focal automatic lenses with rear-focus groups, is completely controlled by software. There are some cameras out there with the old original software and there are others with various levels of software updates. That's why some cameras have that problem and some don't. It has always been an electronic issue, not a mechanical one.

--Chris. does the software update address the "focus jump" and the "soft focus" issue?

All broadcast professional video zoom lenses I've ever had my hands on have a provision for adjusting back focus, whether they're Canon or Fujinon. Hope this helps, -->>>I stand corrected and it does help......thanks Chris

<<<-- Originally posted by steadichupap : Reading "sweeper 7"'s post about backfocus in the Plumbicon days, I found issue with part of his old engineer Neville's technique that is applicable to users of the Canon manual lenses (14x and 16x). As with front focus, back focus becomes more critical with the lens wide open. Thus the adjustment should preferably be done inside in a lower light level, not outside, to achieve the most accurate results. You will need a large space to do this (presumably Neville had a studio at his disposal!)

We did have a studio but not large enough to achieve "infinity focus"

with the camera at one end and the target at the other, but in my opinion, it's better to cheat the distance part of the equation than to perform the task at f11. That said, judicious use of the ND filters, shutter setting and -3db gain setting outside could be use to bring the f-stop towards a workable place (f 2.8 and under). -->>>

Exactly - we used ND filtering to achieve wide open iris.