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noise with D21!!!


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#1 reynald capurro

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Posted 13 May 2010 - 03:51 AM

hi, i'm a french director of photography,
after several tests in panavision france and one commercial, i've noticed an disgraceful "colored" noise in the middle grey and darker part of the image.
i was recording on hard drive in HD 4:4:4 (not raw) using a Log C.
to be safer i was overexposing a bit, the director and i wanted a soft look (cooke S4) . as far as art departement was concerned, no deep colors except a blue jacket for
the actor.
during the color timing, we didn't need to push the "darker" part of the images But we had to face the evidence: noise appeared !!!
in several forum in france i've read the same problem in several dop's testimonial after shooting.
i just love how this camera handle the high light and how beautiful a skin tone can be graceful But this noise is a big issue !

am i wrong? do you have different opinion or experience? can i see images to prove i'm wrong ? thanks.

reynald.
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#2 John Sprung

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Posted 14 May 2010 - 11:45 PM

Can you show us an example? Is it constant or variable? Just a few pixels, or over a large area?




-- J.S.
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#3 reynald capurro

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Posted 15 May 2010 - 04:32 PM

Can you show us an example? Is it constant or variable? Just a few pixels, or over a large area?




-- J.S.


The pixels are constant, colorised ( red blue green) on large areas such as dark blue pull-over , hair, wooden table:
on my monitor (astro) i was on log c and nothing was under 25-30 % !! and the high light were 65-70 %
i know that more and more people around the world shoot commercials, features...with this camera but all the colorist i've been working with in france have also noticed that problem.
i'll try to sent a picture.

thanks. reynald.
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#4 John Brawley

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Posted 15 May 2010 - 05:29 PM

The pixels are constant, colorised ( red blue green) on large areas such as dark blue pull-over , hair, wooden table:
on my monitor (astro) i was on log c and nothing was under 25-30 % !! and the high light were 65-70 %
i know that more and more people around the world shoot commercials, features...with this camera but all the colorist i've been working with in france have also noticed that problem.
i'll try to sent a picture.

thanks. reynald.


Is it possible you're just seeing the noise floor of the sensor itself ? Why are you lifting the blacks up as high as 30% ? If you're lifting them as high as that I would expect you'd start seeing noise in the blacks....

jb
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#5 reynald capurro

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Posted 16 May 2010 - 02:52 AM

Is it possible you're just seeing the noise floor of the sensor itself ? Why are you lifting the blacks up as high as 30% ? If you're lifting them as high as that I would expect you'd start seeing noise in the blacks....

jb



i'm not lifting the black up, 1st: because what i'm filming is not black, 2nd: because i don't touch the level in post to gain some detail in darker aeras.
3rd: the lowest level you can get on the D21 thanks to the log C is 10%, and what is wrong in wanting to have detail in a wooden piece of furniture, or hair and pull-over.??
thanks
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#6 John Brawley

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Posted 16 May 2010 - 07:07 AM

i'm not lifting the black up, 1st: because what i'm filming is not black, 2nd: because i don't touch the level in post to gain some detail in darker aeras.
3rd: the lowest level you can get on the D21 thanks to the log C is 10%, and what is wrong in wanting to have detail in a wooden piece of furniture, or hair and pull-over.??
thanks


But what is the advantage of having black sit at 30% ? Of course you also want some things to be black ? Why wouldn't you put them at say 5% At 30% aren't you just reducing your available dynamic range....

Genuinely wanting to understand your approach.....

I've shot with the D21 and I found that at higher ASA's, in flat fields in near underexposed areas it can have a certain pattern of noise. In fact, I did a DI and the post house rang me to tell me that when they converted it to LOG from REC 709 that was recorded it had huge noise problems and they couldn't go forward ! The noise disappeared into the blacks once they were restored to *normal* though and it ended up looking OK. I also recall seeing the same pattern in The Bank Job, and it's one thing I look for to *pick* if it's a D21 job.

jb
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#7 reynald capurro

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Posted 16 May 2010 - 12:44 PM

But what is the advantage of having black sit at 30% ? Of course you also want some things to be black ? Why wouldn't you put them at say 5% At 30% aren't you just reducing your available dynamic range....

Genuinely wanting to understand your approach.....

I've shot with the D21 and I found that at higher ASA's, in flat fields in near underexposed areas it can have a certain pattern of noise. In fact, I did a DI and the post house rang me to tell me that when they converted it to LOG from REC 709 that was recorded it had huge noise problems and they couldn't go forward ! The noise disappeared into the blacks once they were restored to *normal* though and it ended up looking OK. I also recall seeing the same pattern in The Bank Job, and it's one thing I look for to *pick* if it's a D21 job.

jb




1-the bank job was shot with the D20 and master primes.
2- i guess you were not using the logC on the camera because you're talking about changing the ASA. am i correct?
3- were you recording on tape / hard drive / P2?
4- i could not put the black at 5% (i wish i could) but the logC impose you to have 10% in the darker part of your image!
5- as i said in a previous answer, we can't consider that a blue pull-over is something Black.
6- what do you mean by "they were restor to normal".

thanks for all your answer. take care, reynald.
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