Weird Noise Issue

L

Lenilenapi

Carbonite Member
Ok I've been sitting in my office looking at component output in my Dell and SD output in my Sony 14" (whatever the number is - high rez pro monitor)

There seems to be some voodoo going on with how the HVX treats black & noise. It seems to be independant of the codec or record format.

If you look at an image where it is pretty flat and dark the noise level will come up dramatically, you can really see this in gain.
It can verge on getting blocky and it did seem that way on my dell at 1080, but I don't know what voodoo the Dell is doing at 1080 so that might exacerbate it.

Anyway , set up a darker fuzzy flat image - and slide a sharp white piece of paper into the shot. 2 things happen:
1.- The dark areas get slightly darker. At first I thought this was the monitor, but I confirmed it with the waveform. I don't remember seeing this with other video cameras, but maybe I've never looked that hard. I figure shadows should be independant.
Maybe this has something to do with Flair compensation circuits (do they have those on chips?)

2.- The noise goes way down. This is more striking than the change in exposure.
This could account for some of the noise issue in the "five minute short", but I've never seen the original so I don't want to make any claims here.

It also seems to explain how this camera can seem very clean at some times and noisy at others.

I was experimenting with gain and was struck by how clean the camera looked even at 6. Until you get it on a flat dark area then its as if the codec or something in the camera is hunting for something to grab onto. I don't know how else to explain it.

I've been looking at gain because I know that in doc situations I will have to face being in nightime interiors lit by ordinary room light. They don't look too bad to me at 6. Especially in SD even 9 didn't seem horrible.

The lesson for me seems to be to make sure that your scenes have some area that is decently lit.
You might not be happy doing a horror scene following someone through dark spooky area that go completely black at times.

I do intend to try this with some real shooting tomorrow evening.
I can't say it makes me happy, cause I like Noir and low budget filmakers tend to like it as well.
I'm not sure what it takes to making that noise start rising.
Hope I'm wrong .
Please let me know if others confirm this or if I've been havin' those flashbacks again.
 
Maybe could be some help setting well white balance and black balance? Excuse me but I don't have the camera, so I dunno, but I think this setting could have to do with the problems you've mentioned.
 
Great post. I've seen the noise you are talking about in posted test footage, but many have blamed it on web compression. It's interesting you are seeing this kind of noise directly out of the camera. I hope that you can discuss this issue with others that have the camera (Barry perhaps?) and you guys can figure out how to combat this problem. Keep posting and Thanks!!!
 
Thanks film addict,
I though about looking into this after talking with someonelse on another thread that I can't seem to find. Was that you?
He had observed something similar though it might have been only in posted footage.
By the way, the noise I observed is nowhere near as bad as what was in the "5 minute short" bedroom scene that was posted on the web - no way. But it might have contributed to why the web compression grabbed it & went haywire with it.

I need to retest this when I am more awake and intend to compare with a DVX & other cameras. It doesn't neccessarily mean this is a "noisy" camera because it seems to quiet down quite well when the image has something to latch onto.
Odd that virtually no one has responded to this post yet, compared to everybody who crazy over compressed web pictures. Thanks for keeping it from being buried.
Maybe nobody else can replicate it. That would make me happy.

By the way Danilo, it has nothing to do with black & white balances. They were fine.
I tried Coring to get rid of it & frankly I have a hard time seeing what coring does.
Detail did affect it, but it was there even with detail quite low or off.
 
Yes, I've read this same thing in another thread here.

Hopefully Barry can shed some light on this?
 
This is a very interesting thread. I've noticed exactly what you're talking about in some footage (i.e. Barry's karate and Mirage footage). Dark clips with at least a minor light source seem to be less noisy. If that's true, then I can work around that. I'd like to use this camera for horror genre projects, so I gotta have some solution for dark scenes. I just hate the overboard lighting setups in horror movies these days. It's supposed to be crappy, grainy and dark!
 
It's not an auto gain adjustment, probably something to do with how it processes images. These guys have pulled often a minor miracle with this camera so its not surprising to find some unpleasant compromises.
In a lot of situations you might be able to simply overexpose and then print down, The time honored way of shooting film esp when it was noisy.
In these kinds of shots there is no detail to lose at the top end so you might be fine.
In a doc or dark sitaution it might be tougher.
 
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