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problem with focus on XL1s

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I'm directing a feature on DV. We've shot 2 weeks, and are shooting for another 4weeks, in 5 weeks time. During shooting we had a standard production monitor for checking composition,continuity etc.

 

We noticed that some shots were going out of focus, so we checked focus between each take. they then seemed fine.

 

Now, we have looked at our dailies, projected on a large screen, and everything is out of focus. The camera is searching for focus on all but the brightest shots.

 

We checked the cameras and the projectors, and nothing was wrong.

 

We now have to reshoot 90% of what we have shot.

 

Can anyone explain to me why this has happened? why, when we set our focus, would the camera roam?

 

I'd be interested in your thoughts.

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Hi,

 

What camera are you using? What lens? What settings?

 

Sounds like you thought you had it on manual focus, but it was trying to track manually. I haven't even known of a PD150 dropping into auto focus, although they're notorious for trying to do everything else for you.

 

Phil

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Subject heading says it's the XL-1s. You've discovered the dangers of small monitors. It can be very difficult to judge focus on a small screen. And I assume you were using the standard automatic lens with your XL-1s rather than the manual focus only lens that is available. The autofocus on this camera is pretty poor, especially in low light. I don't find the standard lens that sharp anyway, which makes the auto-focus circuitry have to work that much harder. Consequently it will endlessly search for focus, drifting in and out all the time. You must make sure that you are properly switched into manual focus mode and be very careful not to tap the servo focus ring. Sorry to hear about these problems.

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If you use the autofocus system, 90% chance it is the cause of your problem. This system keeps searching and refocusing all the time, on the very center of the image. If you 're doing a steady shot and the subject is in the middle of the image, it's ok. If not, you're dead.

 

Pulling focus is a "metier", for en easy and quick way for doing it :

Make sure the back focus is okay by focusing in extreme tele position of the zoom. Then enlarge and check that the focus isn't lost while enlarging to widest lens position.

 

I m not shure the focus should be kept all the lens long on this camera. If not, focus at the chosen focal length. If you change the focal length, redo the focus. You can send someone at the different places with such a board as a part of a newspaper page for instance to check focus or do it on the eyes or face of talents.

 

If the back focus seems right, always focus at the longest focal length, then enlarge to the appropriate focal length.

 

Different focus position can be observed along the shot. Have an assistant to change focus along the shots.

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If you use the autofocus system, 100% chance it is the cause of your problem. Autofocus and autoexposure are a sure shot-in-the-foot. I would suggest ditching the standard 16x lens and going with either of Canon's manual lens. They're so much better with focus, detail, and contrast. Sorry to hear the horror story but automatic anything on a camera is totally unreliable.

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