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Panasonic DVX / DVC Assistant
The 4K DVX200 plus previous Panasonic Pro Line cams: DVX100A, DVC60, DVC30.


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Old May 3rd, 2006, 08:36 AM   #1
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dvx100b progressive bug?

Using my DVX100BE in progressive mode, I occasionally find that every 2nd image is significantly softer-focus than the others. This becomes painfully obvious in low light with blown-highlights in out of focus areas, as they start to "pump": every 2nd image blows up the highlights, and then they return to normal for the other images. I use progressive mode, default shutter (1/50s I believe for PAL), autofocus, and optical stabiliser on.

You can see in the linked image, these are 4 consecutive images in 25p, and the woodwork is "pumping" (and is more out of focus) (the aspect ratio is incorrect as these are 1:1 pixel images). Video footage "pumping" at 12Hz is horrible to watch!

http://img104.imageshack.us/img104/8400/dvx100b28rl.jpg

Has anyone observed this problen too? The problem may go away at other shutter speeds, or turning off the stabiliser, I have not experimented.



You know, I like my dvx100be, but with these 3 problems (150Hz noise, strange diagonal lines, pumping images in low light) (see previous posts), I begin to wonder if there is something wrong with my camera. Should I get it looked at by Panasonic?

Thanks
Chris Suzor is offline   Reply With Quote
Old May 3rd, 2006, 06:17 PM   #2
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Auto focus is extremely slow in progressive mode. try manually focusing and see if that helps.
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Old May 4th, 2006, 06:08 AM   #3
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one thing that irritates teh crap out of me, is that when shooting with teh DVX, if you have a blown out element in the background, out of focus, it sometmes "flickers" this is in progressive AND interlaced... and its on BOTH my cameras (100 and 100 a.. ) so its not the camera..

i wouldnt say pump, mor like an interlace artefact...:(

dunno what it is but the workaround is a bit of a pain in the ass..
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Old May 4th, 2006, 12:58 PM   #4
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I've seen this many many times on my DVX100A over the years and it is definitely caused by auto-focus. Sometimes it decides to "go hunting" for more focus, even though the scene is perfectly in focus already. The result can be a very annoying flickering of details. Nowadays I leave it on manual focus and use the "push auto" button when I need some focus assistance. Much better results overall.
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Old May 4th, 2006, 01:41 PM   #5
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Quote:
Originally Posted by Peter Jefferson
if you have a blown out element in the background, out of focus, it sometmes "flickers" this is in progressive AND interlaced...
Sounds like you have your KNEE setting in AUTO. Never use auto-anything if you want to avoid effects like that... try changing your knee to a manual setting and see if it clears up the issue.

Autofocus, autoiris, and auto-knee can all do things like that to you; obviously manual is better for making predictable footage.
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Old May 4th, 2006, 02:10 PM   #6
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Quote:
Originally Posted by Barry Green
Sounds like you have your KNEE setting in AUTO. Never use auto-anything if you want to avoid effects like that... try changing your knee to a manual setting and see if it clears up the issue.

Autofocus, autoiris, and auto-knee can all do things like that to you; obviously manual is better for making predictable footage.
Never thought of that Baz, 9can i call u Baz?? here in Aus Bazza is the Nik for Barry :) )

Anywyas, i DO have knee set to auto, simply coz i really havent educated myself al that much in it... i do know that the 100 (original) doesnt have a knee setting.. so this issue will be prominant on that..

another thing i noticed, is that the 100a, saturation of colours is astounding compared to the flat response i get from teh 100.. i did a shoot the other day, both cams are always set up identically (as far as they can be) and i ve noticed that the black on the 100 arent as crushed (master ped @ -4) while on the 100a, the exposure and colour is absolutetely perfect. In post, i now have to run curves on the 100 to match this..

For over 18months now ive had issues matching the two and nothing i do seems to work.. :(

time to flog off the 100 i think and jump on a HVX. gotta find 10k first..
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Old May 4th, 2006, 08:28 PM   #7
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The same thing happens on the DVC30 and dvc60, we have narrowed it down to the AF hunting and auto iris. This does not occur in manual AF, manual iris, the AF system is similar in the dvx100.
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Old May 4th, 2006, 11:42 PM   #8
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Thanks for the replies, it does look like autofocus hunting, every 2nd image is bad... I dont use auto-knee, and I believe the exposure was set to manual in this example.
I'll have to learn to switch off the AF in these situations, even if Panasonic calls it Assisted Focus in progressive mode!
I feel better knowing it's not an issue with my camera, kind of...
Thanks
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