Gl-2 focus problems

[Tony Marino]

I have shot with the Gl-2 for two days and have noticed that the auto focus is even worse than that of the Gl-1 which is pretty bad. Everyone I know that have used Canon and other brands say this is a problem with Canon and I know from experience from using a Sony before. The problem is when it goes out of focus it takes twice as long to get back into focus than the gl-1. I'll hold the cam by my side while it's on standby, then when I bring it up to start taping again many times it will be out of focus. Also everytime someone or something moves in the path of what I'm shooting it will go out of focus.

Has anyone else had problems with this?

Thank you,
Tony

[Barry Goyette]

Tony

Any autofocus system is going to try to focus on what's ever is near the center of the frame, so if you have your camera set to the side, and it's focusing on something other than your subject...this is normal. Also when someone walks in front of your camera (especially when you are zoomed in), it's natural for any autofocus system to try to focus on them. These are normal characteristics of autofocus systems...and in situations like this it seems like its a good time to switch to manual focusing.

On the other hand, the gl2's focus is definitely slower than the gl1, especially when you are zoomed in and it has to move from near infinity, to near macro. Seeing as it essentially the same lens, my feeling has always been that canon purposely tuned the focus system to move a little slower. Why? Well, the main criticism of the XL1s is that the Autofocus is too sensitive, and that it is constantly hunting...moving back and forth...not locking in on the subject. The gl2 is great at locking in on a subject, holding its focus stable in situations where the flagship xl1s won't (I've tested this). To a certain extent the gl1 also had an issue with hunting focus, And I think canon decided this was a more important issue than sheer speed.

In respect to other cameras in the market...the gl2 has a far greater zoom range than any of it's competitors, and thus the focus has a much further travel when zoomed in, so this in combination with the above may offer some explanation.

Perhaps canon should (they could) add a zone focus feature to a future version of the camera. Even better would be an addition of the eye control technology they use in their still cameras (this may not be feasible due to differences in the viewfinders, but it's a nice thought).

For my money though, I think the manual focus on the gl2 is exceptional, very manual lens like, and in situations such as you've described, would be the way I would go.

Hope this helps.

Barry

[Tom Hardwick]

I agree with a lot of what you've said Barry, but the bit about the zoom range of the Canon has no bearing on its autofocus abilities. If you take a camcorder with a 3x zoom and compare it to the GL2 with its 20x zoom, the focusing mechanism faces exactly the same problems and requirements in each case - it must be able to focus from 1.5m (or whatever the closest focus is) to infinity.

tom.

[Barry Goyette]

Not true. The focus travel on a long lens is substantially greater than a one of shorter length. Test it for yourself on the gl2. zoom the lens as wide as possible, then using manual focus ring, adjust the focus between infinity and a near foreground object. You'll find that almost no adjustment is needed.

Now try the same procedure on the same objects with the lens at maximum zoom. (I just did and it took almost a full turn of the focus ring to bring the near object into focus).

This effect increases exponentially as the length of the lens increases, thus the gl2 with its 20x lens requires perhaps 3-4 times more travel than a 10x lens of half its length. Indeed if both lenses were set at 10x, the travel would be the same, but (again I just checked this) at 10x the gl2's autofocus is essentially instantaneous. At 20x the gl2 took about 1 second to adjust.

I think one of the problems may also be that at 20x, large shifts in subject distance also make it more difficult for the camera to make autofocus judgements. At 20x when shifting from infinity to close-up, the closeup object initially is so completely out out of focus that there is no contrast for the camera to look for...so it must make a preliminary movement in order for it to get information it can judge (somewhat dependant on the contrast of the subject itself). At 10x, even with maximum focus shifts that I've described, very little is extremely out of focus, so the camera has an easier job of making the adjustment.

Barry

[Joris Beverloo]

This is my first post inhere. I do not have a GL2 but I am serious considering to buy one. On internet I read lots of things about this camera already. Some say autofocus is slow and does not react well, howeverothers say autofocus has really been improved and it is very fast. Hard for me to tell what to believe, so I guess the only option is to go to a store and see it in action and play with it myself and see if it is enough for me.
Only one thing I cannot find out in a store. I will use the cam a lot for car racing filming and my question is: if the focus locks on a car passing by, (for example like you are standing next to a highway and you are following a car with the cam) would it hold focus or wil it have problems holding focus since the object comes closer and them moves away again?

Joris

[Ken Tanaka]

The variety of opinions concerning autofocus is more representative of the scenes that people try to shoot with it than the autofocus system itself. It seems that the first thing that people seem to do with their GL2 is take it out of the box, point it at their friend who's wearing dark clothes in a dim room and then whine about how bad autofocus responds. A basic lack of technical understanding.

Expecting any camera's autofocus to track fast-moving object (such as cars) moving nearly parallel to the lens' axis is unrealistic. Shots like these rely on a combination of two things. First, maintaining a deep depth of field by keeping the iris closed-down as much as possible. Second, riding the focus as needed, something that requires more than a bit of practice with an electronically-driven servo focus lens such as the GL2's.

Fortunately, at least in this situation, the GL2 has a deep depth of field in bright outdoor conditions.

My suggestion: Mount the camera on a good tripod, set it to manual focus, focus at a point somethere in the action and adjust the iris (aperture) to control your depth of field.

The GL2 is up to the task. But shooting successfully with any camera, takes skill and much practice and understanding.