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manual focus problem
I’ve seen a few other folks on the forums describing this problem and am wondering if anyone has a solution.
In shooting interviews with 3-point lighting, manual wb and iris, I manually focus my 100b in the traditional way by zooming to z99, focusing, and then pulling back out to frame my shot. I notice that often a) the wider shots are less in focus than the tightest shots; and b) when I pull out wider and then zoom back in for a medium close shot (say around z80-something) the focus has softened and needs to be refocused in order for the shot to be as crisp as it is in a tight close-up.
This was a problem when I first bought the camera (I actually posted here about it back then), and I sent it in to be checked. The Panny repair guys assured me there was nothing wrong with the camera. It doesn’t always happen, but it happens often enough to be a problem, and since I’m noticing a few other folks on the forums are reporting a similar issue, I’m wondering if anyone knows why this happens and how to correct it?
thanks!
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7 Replies
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That’s what we call a back-focus problem. And yes it can be fixed.
Noah
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How is it fixed?
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It’s fixed by a service center re-seating the lens properly.
Noah
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Thanks Noah. When I had it in to the service center (and subsequently to the engineers at Panasonic in NJ), all the software was tested and the lens assembly set to specs. Is “re-seating” the lens something different?
thanks-
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Just take it back again- and tell them the back focus is out.
Noah
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Thanks for the push on this. I sent the camera to Digitron Electronics in LA, per the recommendation of another poster on the forum. The technician there suggested replacing the optical assembly, so I think (hope) I’m on to finally correcting this issue instead of the temporary fixes so far. Do you have any experience with/opinions on Digitron?
thanks-
Ruby -
I know this is an old post, but it’s important for Panasonic owners to know that sometimes backfocus-like issues do come up in the cameras. I’ve seen it in multiple HVX200A and HVX200 cams, and an HPX170. I went through a year of repair-hell with Panasonic repair. They would say the camera was fine and send it back to me, but the lens was definitely not holding focus throughout the zoom range. They replaced the lens TWICE on one camera, but still couldn’t fix the problem, and it took three more replacement cameras before I finally got an HVX200A camera that focused as it should. Be aware that if you have the same issue, Panasonic techs may not be able to fix it (if you can even get them to see it), and replacement may be the only option. A colleague of mine had the same issue with his HVX200A and similarly had to argue with Panny repair for them to see the issue. Panasonic West Coast repair under Jim Fast may be a different experience.
A simple test to see if your camera holds focus throughout the zoom range is to open the aperture, zoom in all the way on a chart on a wall about 15′ away, set the camera to auto-focus and note the focus distance that comes up. Now zoom out to about 10mm and see what focus distance comes up then. Expect some variance (max 1-2 feet), but it should not be a huge change. I.E., if the focus distance comes up as 10′, your camera has problems. Perform a similar test on a wall/building 50′-75′ away. If the focus reading stays within the DOF range, you’re OK.
This link has an excellent DOF calculator to check acceptable focus variance. For a 1/3″ CCD camera, enter .004 in the “Custom CoC” box at the top right. https://johndudak.com/photographers/dof.php
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