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Panasonic AVCCAM AG-AF100 Camcorder
Large-sensor AVCHD with interchangeable Micro 4/3 lenses.


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Old January 29th, 2012, 03:00 PM   #1
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AF100 Shadow Blocking - What's the Problem?

I shot some footage the other day for a quick spot promoting a musical performance. Used the AF100, EOS lenses, and lit with kino-flos. Basic setup, nothing crazy. This was recorded with the AVCHD onto SDHC cards and I was using the Marvel's Cine preset (on second look, I think this takes too much color out of the image).

I brought the footage into Final Cut X, converted to ProRes, and did some very subtle color correction - dropped the mids a touch and added back some saturation. Looking more closely, however, I saw a problem:

I'm seeing shadow blocking in nearly all of the shots if I even so much as touch them with any type of filter. A subtle vignette filter magnified the problem. I've attached a few screen grabs to illustrate the issue (I upped the brightness just a little bit in quicktime to highlight it a bit more).

What is causing this? Is it normal? Is there a problem with my camera color preset? Would something like a Ki Pro remedy this sort of thing? Any thoughts are appreciated, thanks.
Attached Thumbnails
AF100 Shadow Blocking - What's the Problem?-example-1.jpeg   AF100 Shadow Blocking - What's the Problem?-1-detail.jpeg  

AF100 Shadow Blocking - What's the Problem?-example-2.jpeg   AF100 Shadow Blocking - What's the Problem?-2-detail.jpeg  

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Old January 29th, 2012, 05:35 PM   #2
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Re: AF100 Shadow Blocking - What's the Problem?

Question - does the pattern of the blocking alter on a roughly 1/2 second cycle? If so, I'd be pretty certain it's down to the AVC-HD compression.

If not (and this is more likely the case) it's probably down to the front end of the camera, and the signal processing exacerbating quantum steps at the very front end. You will likely be able to reduce the effect by using a different set-up - but then the camera won't have the "look" you want it to! This is not the first story I've heard of line up of this camera having to be set to minimise blocking, noise etc, as opposed to setting to get most pleasing picture.

It also looks very like noise reduction in camera - minimises visible noise, but at the expense of giving just such "blockiness".
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Old January 30th, 2012, 02:25 AM   #3
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Re: AF100 Shadow Blocking - What's the Problem?

Auch! That looks really blocky! Did the jpeg compression made it worse?
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Old February 6th, 2012, 10:19 AM   #4
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Re: AF100 Shadow Blocking - What's the Problem?

I would initialize the camera and start over with your scene file. The lighting looks pretty flat and not very flattering. Or that is your scene file? Start over and try again. Look at the WFM and see what your contrast is. Not familiar with the Marvel scene files.

Off hand, though this looks odd overall. Is this a frame grab off of the camera? or is it off of the timeline. If on the timeline, how was it processed? Which system? Did you convert to ProRes or use the Panasonic Plug-in?

More details about the settings in your camera and the lighting on set would help give a more useful set of suggestions on what went wrong here.

Best,

jan
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Old February 6th, 2012, 02:25 PM   #5
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Re: AF100 Shadow Blocking - What's the Problem?

I don't know, looks pretty par for the course to me... simply a limitation of the codec/8 bit supply chain?
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Old February 6th, 2012, 04:41 PM   #6
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Re: AF100 Shadow Blocking - What's the Problem?

Thanks for your responses everyone. I spent some time with my HDTV tuning the camera via HDMI and I think a strange picture profile was to blame. I wiped them out and started over with a few recommended by Abel Cine and also a few of my own.

The profile I used when shooting seemed to be pretty messed up, especially in the pedestal setting and how it was handling noise in the darks. Starting with the "Clean" profile setting from Abel and tuning to my preferences seemed to make much of a difference.

I also learned that I should shoot closer to the image that I want. It was one of my first outings with the cam and I think I tried to flatten the image a bit too much because I was unsure of what my results would be.

Doing another similar shoot Wednesday and Thursday so I'll see how it goes. Thanks again!
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