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F900/3 Posible problem?


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#1 Chriss Kostabill

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Posted 08 August 2006 - 01:49 PM

Hello this is my first post in the forum, but sadly it is'nt for good!

Last week we shot a comercial with our new sony f900/3. We had a scene in a balcony with background a bright sky. We used a polarising filter so the sky was recorded normal but the camera and zoom was perfectly still.
When we shoot it the DP noticed that the sky was changing his brightnes (from lighter to darker blue). Later in post this phainomenon was confirmed.

Did anyone knows what is causing this problem?
Thanx in advance.
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#2 Brian Dzyak

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Posted 08 August 2006 - 04:29 PM

Hello this is my first post in the forum, but sadly it is'nt for good!

Last week we shot a comercial with our new sony f900/3. We had a scene in a balcony with background a bright sky. We used a polarising filter so the sky was recorded normal but the camera and zoom was perfectly still.
When we shoot it the DP noticed that the sky was changing his brightnes (from lighter to darker blue). Later in post this phainomenon was confirmed.

Did anyone knows what is causing this problem?
Thanx in advance.


What time of day?
Was the exposure control on the lens on auto or manual?
Was the exposure on the foreground elements consistent or was the overall exposure changing?
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#3 David Mullen ASC

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Posted 08 August 2006 - 07:38 PM

Was DCC on and was anyone moving in front of the sky to cause the DCC (Auto Knee) to keep changing?
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#4 Chriss Kostabill

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Posted 09 August 2006 - 02:16 AM

Hello and thank you for your answers.

What time of day?
Was the exposure control on the lens on auto or manual?
Was the exposure on the foreground elements consistent or was the overall exposure changing?


I think the shot took place around 10-12 o-clock in the morning.
The exposure on lens was definetely on manual.
The exposure on the people, floor in front of the balcony was not changing. The only part of the image that changed was the sky.

Was DCC on and was anyone moving in front of the sky to cause the DCC (Auto Knee) to keep changing?


DCC was enabled but there was little to none movement in parts in front of the sky.

Notice that we continue shooting some close-ups from different angles with the same settings and this behavior it did'nt took place again but I'm afraid that this is going to happen again without any warning!

Thanx for your time!
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#5 Simon Wyndham

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Posted 09 August 2006 - 02:30 AM

I think it could be the DCC. Sounds like the XDCAM HD cameras. The DCC on those can't be trusted as they continually cause 'jumps' in brightness in areas of the picture, even if things aren't changing too much.
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#6 Elhanan Matos

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Posted 10 August 2006 - 12:50 AM

Sounds like DCC to me as well, but if you had a remote paint box like an RMB-150 or 750 plugged in the auto-iris button could have been on.
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#7 Chriss Kostabill

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Posted 10 August 2006 - 02:24 AM

Thank you all for your response.
I'm very suprised that dcc could change the brightnes of areas in picture in such static shots. Today (if I have the time) I will run a test and simulate the shot to see how dcc is responding to foreground non highlight changes.
Thanks again!
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#8 B. Schultz

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Posted 14 August 2006 - 02:41 PM

Thank you all for your response.
I'm very suprised that dcc could change the brightnes of areas in picture in such static shots. Today (if I have the time) I will run a test and simulate the shot to see how dcc is responding to foreground non highlight changes.
Thanks again!


Don't be surprised at all! I have had lots of problems with this circuit (DCC-ON switch) and am very annoyed that Sony has supplied no provision to disable the camera switch in the menus. Many times a soundperson will accidently switch this to DCC-ON from laying down bars and the camera will occaisionally render the same results you have described. Even though some major players swear by this circuit, I refuse to use it because you can easily be screwed by it without noticing it in the field.

A better way is to achieve the exact same highlight suppression result through careful use of the paint menus. I have found the Digital Praxis Log709 curve emmulates the DCC-ON circuit nearly exactly with no "surging" side effects. It's a free download from their website and once installed takes about 10 seconds to activate. I have it installed as one of my 5 basic scene files and use it anytime I might be inclined to use DCC-ON.


Bruce Schultz
F900/Varicam owner/operator
LA-based IATSE 600
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#9 Simon Wyndham

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Posted 15 August 2006 - 11:40 AM

You could try changing the DCC mode to FIX in the menu. That way if the switch is accidentally knocked the knee will be in a fixed positon rather than changing all the time.
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#10 B. Schultz

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Posted 18 August 2006 - 02:06 PM

You could try changing the DCC mode to FIX in the menu. That way if the switch is accidentally knocked the knee will be in a fixed positon rather than changing all the time.


Simon, could you elaborate more on this menu option? What page, which option#?
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