• Panasonic Cameras

  cine style lens focus problem

  Posted by Bruce Greene on November 21, 2005 at 5:29 am

  I’m the proud new owner of a varicam (model H) and a cine style wide angle zoom.

  Here’s the problem: When the camera is cool (1st 1/2 hour) and the back focus is set, the footage marks are right on. As the camera warms up focus drifts and I re-set the back focus.

  This much I kind of expected. After 2 hours of the camera powered on though, the footage scale shifts by about 5 witness mark thickness. In other words, to focus at 5′ one now has to focus at 4’8″. The focus looks quite good and tracks well from telephoto to full wide, but as the camera gets warm, the footage scale needs a new witness mark for focus by distance.

  Shouldn’t the focus stay accurate when the back focus is adjusted correctly?

  When the room is warm (ie. 85 degrees F) the problem is even a little worse.

  So is the footage scale shift typical of HD zooms, or do I have a lemon lens.

  Thanks all,

  -bruce greene

  Bruce Greene replied 20 years, 6 months ago 1 Member · 0 Replies
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