Canon 16x Manual Servo lens backfocus? at DVinfo.net

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Canon XL H Series HDV Camcorders
Canon XL H1S (with SDI), Canon XL H1A (without SDI). Also XL H1.


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Old July 21st, 2013, 08:17 PM   #1
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Canon 16x Manual Servo lens backfocus?

Hi there -

This is in reference to the XLH1.

I have just dug out my Canon 16x manual servo and am having a bad time adjusting the back focus or flangeback adjustment.

Here's the process I have tried:

I set the little "macro" thingy to the non-macro position (with the little red thing on the barrel clinked into it's slot)

Then I set the camera 6 feet away from a wall with a hanging patterned rug for focus.

I set the lens barrel for 6 ft.

I zoom in to max and focus using the FB adjustment. I zoom out. But now it's way out of focus. I set FB focus for the zoomed out position and then zoom in again. Out of focus.

There does not appear to be a sweet spot where I can get both near and far focus good by using the FB adjustment on the lens itself.

Obviously, the automatic FB adjustment does not work on this lens (at least I don't think so). Anyway, it's greyed out in the camera menus.

I am wondering if this inability to find a good focus spot on the FB adjustment ring might be because the position within the camera of the sensor is set to the previous lens which was used on the camera.

If so, does anyone have a process or any bright ideas?

many thanks,

Harry.
Harry Bromley-Davenport is offline   Reply With Quote
Old July 21st, 2013, 09:51 PM   #2
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Re: Canon 16x Manual Servo lens backfocus?

First off download a Backfocus chart and print it.

Instructions:

To adjust back focus you need a focus chart or an object with fine detail. Focus the lens on a near by object or focus chart. Zoom the lens all the way in. Now zoom back until detail starts to blend together and refocus. If the focus stays the same throughout the zoom range, the back focus is OK. If you have to refocus between telephoto and a wider-angle position, back focus needs adjusting. At a wide-angle position, release the screw on the back focus ring and turn it. Notice that focus goes out in both directions just like focusing the lens normally. You will use this to reset back focus.

Zoom in and focus with the regular focus ring, then zoom wide and focus the back focus ring. Continue doing this until you no longer have to adjust the back focus ring. Carefully tighten the back focus screw and recheck if the lens still "holds focus" for the whole zoom range. Now the lens distance calibrations should also be correct.
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Old July 21st, 2013, 09:57 PM   #3
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Re: Canon 16x Manual Servo lens backfocus?

Ahhhh ..

So, when adjusting the back focus, I have to simultaneously adjust the back focus ring AND the actual (front) focus ring.

I was trying to get it right by setting the lens to 6ft and then ONLY adjusting the BF ring. It sounds like there is a lot of trial and error in this.

Correct?

Thanks you so very much for your advice. You will receive a big GOLD STAR in your copybook.

Best wishes,

sincerely,

Harry.
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Old July 21st, 2013, 09:59 PM   #4
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Re: Canon 16x Manual Servo lens backfocus?

You can download and print a backfocus chart here. Actually if you follow those directions it's a snap.

Free Video Camera Lens Focus Chart | VFGadgets.com
Al Gardner is offline   Reply With Quote
Old July 21st, 2013, 10:00 PM   #5
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Re: Canon 16x Manual Servo lens backfocus?

Thank you so much.

Now you get TWO gold stars.

Best wishes,

Harry.
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