weird xl2 focus issue with manual 16x lens

Georgi Ivanov · January 4th, 2007, 09:47 PM

I had out of focus problem with XL2 recently. I used 20x Canon lens on manual focus. Open iris probably F 2 (not very bright scene). I got the focus manually zooming in (tele position) on the object. When zoomed out (wide position) the main object got blurry (completely out of focus). When zoomed in on it again the focus was o'k. There was no way to see that on the small XL 2 monitor. I found this out later during the editing on our studio monitor. The camera is about 6 months old not used very often.

Greg Boston · January 4th, 2007, 11:58 PM

Quote:

Originally Posted by Georgi Ivanov

I got the focus manually zooming in (tele position) on the object. When zoomed out (wide position) the main object got blurry (completely out of focus). When zoomed in on it again the focus was o'k. There was no way to see that on the small XL 2 monitor. I found this out later during the editing on our studio monitor. The camera is about 6 months old not used very often.

Georgi, that's a classic back-focus issue. Unfortunately, it's not user adjustable on the 20X XL2 lens. Sending it in to Canon is currently the only way I know of to get it fixed.

-gb-

Georgi Ivanov · January 5th, 2007, 04:33 PM

Thank you! This is what I thought. We called Canon and sent them the camera and the lens about two weeks ago actually. I just wanted to share that such thing happened with almost brand new lens.

Josh Bass · March 13th, 2007, 11:55 PM

Gentlemen, might this have anything to do with it?

I got bored and read up on the more techy aspects of the camera, via the XL2 Watchdog page.

From this page:

http://www.dvinfo.net/canonxl2/articles/article06.php

I refer specifically to this part:

"Note that the target areas for both the widescreen 16:9 and standard 4:3 aspect ratios are smaller overall than the actual CCD area itself. There are two primary concepts to understand with regard to the size of the XL2's smaller target areas. First, although these areas are physically smaller than the previous XL1 and XL1S which utilized the entire one-third inch sensor, the XL2 is providing more pixels and therefore higher image resolution within its target area compared to the XL1 and XL1S (345,600 pixels in the XL2 compared to 250,000 pixels for the XL1 and XL1S in standard 4:3 mode for NTSC models). Second, because these target areas are smaller in the XL2 than they were in the XL1 and XL1S, there is a slight magnification in the field of view for all XL-mount lenses. The multiplication factor for using an XL lens on the XL2 is 1.105 in the widescreen 16:9 aspect ratio and 1.35 in the standard 4:3 aspect ratio. Basically this means that all XL lenses are just slightly more telephoto on the XL2 than they are on the XL1 or XL1S."

I'm no expert in optics, but wouldn't a slightly more telephoto image result in slightly less (i.e. shallower) depth of field at all focal lengths?

January 4th, 2007, 09:47 PM	#16
Georgi Ivanov Tourist Join Date: Dec 2006 Location: Walnut Creek, CA Posts: 3	Out of focus problem with 20x lens I had out of focus problem with XL2 recently. I used 20x Canon lens on manual focus. Open iris probably F 2 (not very bright scene). I got the focus manually zooming in (tele position) on the object. When zoomed out (wide position) the main object got blurry (completely out of focus). When zoomed in on it again the focus was o'k. There was no way to see that on the small XL 2 monitor. I found this out later during the editing on our studio monitor. The camera is about 6 months old not used very often.

January 5th, 2007, 04:33 PM	#18
Georgi Ivanov Tourist Join Date: Dec 2006 Location: Walnut Creek, CA Posts: 3	Thank you! Thank you! This is what I thought. We called Canon and sent them the camera and the lens about two weeks ago actually. I just wanted to share that such thing happened with almost brand new lens.

March 13th, 2007, 11:55 PM	#19
Josh Bass Slash Rules! Join Date: Apr 2002 Location: Houston, Texas Posts: 5,472	Gentlemen, might this have anything to do with it? I got bored and read up on the more techy aspects of the camera, via the XL2 Watchdog page. From this page: http://www.dvinfo.net/canonxl2/articles/article06.php I refer specifically to this part: "Note that the target areas for both the widescreen 16:9 and standard 4:3 aspect ratios are smaller overall than the actual CCD area itself. There are two primary concepts to understand with regard to the size of the XL2's smaller target areas. First, although these areas are physically smaller than the previous XL1 and XL1S which utilized the entire one-third inch sensor, the XL2 is providing more pixels and therefore higher image resolution within its target area compared to the XL1 and XL1S (345,600 pixels in the XL2 compared to 250,000 pixels for the XL1 and XL1S in standard 4:3 mode for NTSC models). Second, because these target areas are smaller in the XL2 than they were in the XL1 and XL1S, there is a slight magnification in the field of view for all XL-mount lenses. The multiplication factor for using an XL lens on the XL2 is 1.105 in the widescreen 16:9 aspect ratio and 1.35 in the standard 4:3 aspect ratio. Basically this means that all XL lenses are just slightly more telephoto on the XL2 than they are on the XL1 or XL1S." I'm no expert in optics, but wouldn't a slightly more telephoto image result in slightly less (i.e. shallower) depth of field at all focal lengths? __________________ The Bass' camerawork The Bass on IMDB