HPX250: HPX250 intermittent softness in strong daylight

S

surfcitizen

Member
Was shooting today on my HPX250 at AVC I 100 30p using CINE D & PAP 1 with mostly excellent results. It was under a bright noon sun with some light passing cloud - not a low light situation. I was able to keep the iris close to 4.0 most of the time by using ND 1/64 and a circular polarizer and was getting nice results from the full zoom range including both ends. However a couple shots are WAY soft and I'm trying to figure out why as the remaining 40 shots are fine. Here's a link to the 2 shots if anyone has any ideas on why this is happening.

I'm aware of the issues discussed with this camera and have mostly been able to work around them but can't figure why these shots went soft and the rest don't. As you'll see, I pulled back on the first shot from full tele to full wide and just before hitting wide it went soft. The next shot was zoomed in some but still remained soft and then came clean right at the end of the tele range. I did the same at least five times before and after without any problems - and without changing anything on the camera. Any input would be much appreciated.


https://vimeo.com/61318084
 
Without having the actual HPX-250 and knowing the other 40 shots, I can only speculate something's up with the KG's servo zoom and back focus is a hair off alignment due to temperature or humidity factors. It may be fine now in normal stabilized environment. Come to thin of it, there's no back focus adjustment on the HPX-250. I guess any internal deep cleaning or lens maintenance must be sent back to Panasonic for service. Not sure if the 5-yr warranty covers that.
 
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Added note: B4 2/3" lens mount is known to expand and contract a very small amount on temp fluctuations. I was driving from a warm 85 deg. F Nevada desert into a 40 deg. F Utah snow a while back. Did notice a bit out of focus when servo zoom is performed on the lens. It can be a combination of temp fluctuation or prolonged shock impact to the lens from the long drive. Couldn't figure out why at that time. Now I always bring a portable 8x11" back focus chart on all field shoots and from time to time micro adjust the back focus to have razor sharp lens fr all zoom ranges. It won't hurt to buy extra shock protection padding in addition camera's hard or soft case. This helped me tremendously and i haven't experience much of the out of focus issue ever since. Not sure how the HPX-250's KG lens internally can automatically adjust for back focus. It's quite disturbing to know that it's occurring on other user's cam.
 
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OMG...that's soft! Contact your reseller and/or Panasonic and show this video to them. I had very similar results in a theater in some specific lighting set-up (mostly with some sort of blue lights). But having this problem outdoors...man, Panasonic should really get their hands on your cam.
 
I'm wondering if these issues are related to PAP 1? From what I've read, the distortions/micro-jelly are rare but perhaps in certain conditions it becomes more pronounced or more likely to occur. I wish I had time to do some testing.
 
If those 2 shots were done in manual focus and you didn't touch the focus ring while shooting, there is something wrong with the camera. The only way to get something that out of focus at full wide angle on a 1/3" chip camera at ~ F/4ish is to put the focus into macro mode!?!
 
I swapped over from PAP 2 to 1 recently in an effort to correct this problem. It seemed to help some but because the problem is so intermittent I can't really tell if it's any improvement.
 
Going out of focus as you zoom from narrow to wide is pretty much the classic symptom of a lens with mis-set back focus. On an old time ENG lens I would just unscrew the locking ring and make an adjustment -- but things are much different in these modern electronic lenses that are constantly adjusting their internal focus and aperture settings as you change focal lengths, and where there's no user accessible back focus control. I'd say Panasonic service should get a call.

- Greg
 
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