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Old July 12th, 2003, 01:43 PM   #1
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Homemade Follow Focus?

Has anyone tried to make a follow focus unit for smaller DV cameras? Is this even worthwhile (as the focusing ring on DV cameras seem to work so wonky with the servos or whatever it uses...). Would a LANC controller be better?

I'm thinking it would be a nice add-on to the Centurty DV matte box if it would actually give some benefits. I'm pretty crafty with casting in resins and light machining so I think I could do it....but I'm not sure of the design...

Are they geared to allow quicker turning of focus or for finer adjustments?

I have a PDX10, which would of course be overkill...but it would be fun to try it!
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Old July 14th, 2003, 04:39 AM   #2
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As far as I understand it this would be pretty useless on the
standard DV lenses since they are server controlled. So you
really don't have a beginning and ending or real way to control
the lense. I do think a lanc controller would be better in this
case indeed (try before buying though!).

If you would have a full manual lense like the 14x or 16x you
can buy for the XL1 then it might be an option
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Old July 14th, 2003, 02:25 PM   #3
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I just posted something about this in the 'for sale' area...

If you look at the major people selling the follow focus units it seems without exception they are using the stock lens for the XL1S.

http://www.virtualcybervision.com/xl...20solution.htm

as an example..


I'm sure it would be better with the manual lens... but I wonder if it works as well with the stock?

Also, while we're sort of on the subject:

What about the VeriZoom units for focus and zoom? Do they work with both.
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Old July 15th, 2003, 07:41 AM   #4
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I don't know the answer for that, Kevin. Perhaps send an e-mail
to them if no-one else responds here?
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Old July 15th, 2003, 11:31 AM   #5
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Kevin, thanks for your link. I can see (somewhat) how the follow focus units work. I checked out VariZoom's site and yes, their units control both focus, zoom, and even more on some models...

I agree that for internal focused cameras, a Lanc controller might make more sense, but I guess I like the idea of a more "analog" interface--some big dial that would give me a better feel and sense of control instead of a small rocker-switch or button found on the Lanc units.

I'm not interested in a "true" follow-focus unit; one which you could add marks on for focus pulls, etc., I'm just looking for a better sense of control and feel. But I guess if any mechanical/geared/dial interface is ultimately linked to a servo-controlled internal focus lens, maybe the effort of making this focus-dial-type focus control is pointless? Or maybe not?...

The thing about IF camcorder focusing rings is that they are not at all linear. They function on two variables: the distance I turn the ring, and the SPEED at which I turn the ring. I can turn the ring very slowly 1/4 turn and see that the distance displayed goes from 0.2M to 0.3M. Or, if I turn the ring very fast over that same 1/4 turn, I go from 0.2M to infinity. Wouldn't it be nice to be able to amplify the travel that the focusing ring makes by gearing it to a follow-focus-type dial on the side of the cam? I would hope that I could make more finite adjustments by turning this type of dial 1/32nd or less of a revolution (though maybe it would be trickier, too...)

Any Lanc unit users out there who care to chime in on the sense of control or feel of these units? I remember using one years ago and I don't think I was too impressed... hard starts and stops on the zoom, though they may have gotten better....
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Old July 16th, 2003, 04:33 AM   #6
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What you might obtain with such a system is that you can control
a slow zoom/focus shift more easily. However, I don't see how
you are going to get the gears to rotate the rings on the lens.
Also, since at least on the XL1 the rings are sensitive I don't
think you could get a fast zoom consistent with such a setup.
Only a slow one.

But then again, it might be worth trying out with some things
thrown together cheap to see what happens....
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