GL2 autofocus lag can be a problem at DVinfo.net

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Canon GL Series DV Camcorders
Canon GL2, GL1 and PAL versions XM2, XM1.


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Old October 21st, 2002, 11:23 AM   #1
Jack Durban
 
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GL2 autofocus lag can be a problem

I have been shooting Soccer matches for the past two weeks with the GL2 and have noticed a real potential problem with auto focus at medium to long range in zoom. I shot over two hundred games on a Sony VX3 so I am used to focus lag but this is more than a reasonable lag. There are times when auto focus can actually hang for seconds before it locks on target.

This just might be my cam but I wanted to put this out for some to ponder if you are in evaluation mode.

By the way, Zotzdigital.com is by far my best online purchasing experience. Brian and his team are the best. No upselling, fast and friendly, and the price was just a bit above the grey market hacks out there that make you feel like taking a shower after even talking to them!
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Old October 21st, 2002, 12:00 PM   #2
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Hello Jack and Welcome,
Indeed, Canon's prosumer cameras have a reputation for sluggish and often confused autofocus systems. I know that my GL2 and my XL1s (16x auto lens) can sometimes hunt for focus far too long even on a well-lit scene. I've read that the system does best if it finds a vertical line near the center of the frame, but I've not verified that.

For many folks the solution is to just use manual focus, occassionally using autofocus momentarily to snap critical focus.
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Old October 21st, 2002, 01:23 PM   #3
Jack Durban
 
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Thanks Ken. I missed that one.

I had no idea that this was an inherent issue. I poured over quite a few articles and two reviews and failed to see any auto focus issues. Oh well, I guess I have to master manual focusing with a Varizoom.

I am using a varizoom PGL LANC controller and it is a little awkward to both zoom and focus together without dislocating your thumb!

I do love the GL2 overall. The most incredibly rich color and detail I have ever seen at this price range. The digital zoom like all others however is a joke and should be left to the cheezier lower end cams. I always love those ads that boast "800X digital zoom".

Take Care.
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Old October 21st, 2002, 01:52 PM   #4
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Focus lag was also in the GL1 and I have noticed it occasionally in the GL2. The GL2 autofocus is better however; aside from an occasional lag, normally it works well. It is more accurate than the GL1 with minimal hunting in my opinion.
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Old October 21st, 2002, 02:01 PM   #5
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Jack,
Most frequently you'll see folks complaining about the autofocus system on the XL1/XL1s 16x auto lens. The work-around on these cameras is to purchase one of the manual lenses available for that camera.

But the GL1 and GL2 lens features (to my knowledge) the same a.f. system. I've not used my GL2 enough yet to make a true comparison. But I did own a GL1 for several years and noticed that its a.f. could also become befuddled rather easily. I -suspect- that, programming being equal, the GL2's system is a bit better than its predecessor's, if only due to the GL2's slightly higher CCD resolution (higher sampling). I've only had trouble with my GL2's a.f. when shooting hovering helicopters at close range at twilight, which would be expected given the subject and relatively low light and contrast.

Hey, maybe you can sponsor one of the soccer teams you shoot and buy them all jerseys with black and white VERTICAL stripes, eh? <g>

p.s. I love your tagline, Jack!
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Old October 21st, 2002, 06:22 PM   #6
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Jack

I have to agree with you that the GL2 is a bit slow at making large focus shifts (the kind that come with telephoto shots). On the other hand, I think this characteristic is responsible for a more stable focus "lock" of the gl2 when compared to the xl1s, which often has too much sensitivity and speed, and thus can't ever decide what to focus on.

While I occasionally cuss while I wait for the gl2 to find and focus on something in the foreground when I'm zoomed out, I have to say I'm really happy that once it gets there, it typically stays rock solid on the subject, rather than hunting like its big brother does. Personally, I think Canon has made a tuning decision with the gl2, perhaps in response to all the bitching about the xl1s. I think the gl1 hit the happy medium between the two, although I think the gl2's stiffer focusing makes it a superb manual focus camera.

Barry
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Old October 21st, 2002, 06:58 PM   #7
Jack Durban
 
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Hi Barry I respect your opinion and have a followup question

Thanks for the help by the way. Would you recommend a slower rate of zoom to accomodate the design?

Also... I am shooting soccer matches from a ladder with a monopod. After 6 years and hundreds of games later I really want to take the next step (no pun intended) in quality, hence the GL2 from a Sony VX3 Hi-8. Being tethered to the camera via the eyepiece makes wide swing pans a real balancing act to maintain level. I am thinking about taking an old Miller fluid head and attaching it to machined bracket that will be hard fixed into a portion of the ladder. I was also going to buy a 7" LCD TFT monitor and build it into a 6" deep rectangular Zero chassis to provide protection and hood. This monitor is going to reside behind the camera tilted slightly upward so I can shoot behind the cam instead of married to it. It will be like a miniature broadcast cam used at the big stadiums.

Any thoughts from the peanut gallery?

And many thanks again.
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Old October 21st, 2002, 07:56 PM   #8
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I don't do much of this type of shooting, so I wouldn't place too much credence in what I'm about to say, but this seems like a reasonable approach:

I would experiment with setting the camera to manual focus, and picking a point middle-far in the field, zoomed in tight, and set your focus. Try to keep your aperture around f5.6, by using AV mode or manual. As the players get closer to you, zoom slightly wider, and the camera should retain good focus. Then as you zoom in again for long shots, the focus is already preset in that area...tweak by hand as necessary.

I'm not sure about mounting your camera to the ladder, as it will be subject to any weight shifts, or wobbles in your balance. I would take that ol' miller and mount it to a tripod where it belongs (my balance isn't so good, and I've been "saved by the tripod" several times in my career, as I start to believe the viewfinder image rather than newtonian physics). Bogen makes some decent "tall" photo tripods that will get you up over 7 feet for a reasonable cost.

An external monitor, mounted off the camera platform would be a great idea, as would a remote focus and zoom controller, like one from varizoom. I have the Stealth and it works pretty well.

Barry
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Old October 21st, 2002, 08:21 PM   #9
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Jack,
With respect to the external lcd monitor, try to get the best model you can afford. The resolution of the least expensive models is very coarse and will make it even more difficult for you to detect focus, not to mention their terrible color reproduction. Nebtek (nebtek.com) makes a mid-priced unit which reportedly is pretty good on the resolution and color fronts, as well as featuring a screen bright enough to see in daylight. The best (in my opinion) is a Panasonic lcd (TC-7WMS1) which is very bright and features excellent, full-frame switchable 4:3/16:9 resolution. (I use one and love it.) Nebtek also markets this same monitor with a power adapter enabling it to run from the same BP line of batteries that you use for your GL2...very handy. Alas, however, this tricked-out Panasonic rig will set you back $1,000.

Also note that Hoodman (hoodman.com) makes a flexible nylon/foam hood for this monitor which weighs nearly nothing and easily detaches (Velcro) and folds for easy stowing. My Panasonic monitor came with this as part of the kit, but I'm not sure that Nebtek's version features the same kit. Best to call them if you're interested.
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Old October 21st, 2002, 11:47 PM   #10
Jack Durban
 
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Points well taken and appreciated

The Miller head is on a $2K tripod now but I was tempted... to Frankenstein it to get up higher. I'll check the bogen first. I already use the Varizoom PGL for remote zoom and rec/pause.

I really didn't really consider resolution on the monitor, DOH!.

What an oversight. I was going to go to Fry's and pick up an OEM monitor for a couple of hundred bucks only to find what you warned of. It could have looked as bad as a digitally zoomed image, or what I call video as viewed through a shower door!

Knowing how poor Fry's return policy is I was probably going to have to eat it.

Glad I asked!

Time to start saving for a real monitor.

Thanks you guys!
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Old October 22nd, 2002, 07:32 AM   #11
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Auto focus needs a reasonable light level to stand a chance of working well, (over 50 lux in the case of the XL1). It also likes to see vertical edges (contrast) in the image center - no venetian blinds please.

A smaller CCD gives greater depth of field for the same f-stop and field of view, and this can give the impression of auto focus working somewhat better.
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Old October 27th, 2002, 12:13 PM   #12
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i've done quite a few shoots in nightclubs with my XM-2, and the autofocus hates it, especially in situations where 12db gain or more is needed just to see an image on the LCD screen

often, once the image is out of focus, the AF can do nothing to correct it, unless I zoom in on an object, or go into manual, focus roughly and then click back into auto.

It must be all the birght spots of light zooming around the room, i'm sure it confuses the hell out of the circuitry, but it does seem a bit strange the way focus just stops dead once it is confused instead of hunting.
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