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Old February 21st, 2008, 02:49 PM   #1
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HPX500 Noise issue

Hi all,

I recently got one of these for a days test from Panasonic. The stuff we shot was in a well lit room and I found looking at the raw quicktime files on my mac that it seems very noisy.
I shot a girl against a green brick wall and the wall seems to be alive with noise.
We shot at 1080i on zero db.

Is this camera known for noise? I've used a sony HDCAM and so far the HPX seems sharper but the footage I've seen is so much more noisy.

As I don't have much hi-def gear I can only look at the raw quicktime files on my mac so maybe it's a codec issue with quicktime.

Also is noise a bigger issue when shooting at 1080 instead of 720 because of the interpolation?

Can anyone shed some light on this problem? This is a camera we intend to buy two of but if the noise level is this bad then I'd sooner not bother.

Input from HPX500 users would be extremely valuable.

Thanks
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Old February 21st, 2008, 05:05 PM   #2
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Hi David,
I guess it depends on what you are comparing your images to. But we have two of the 500's and are thrilled with the images we're getting. I have shot stuff in very dimly lit rooms where noise starts to show up. But except for those very dark environments, your footage should be beautiful.

I have seen direct comparisons between the 2000 and the 500 in really low-light situations, and the 2000 returns a noticeably better image. But again, this was in really dark environments.

Can you post a couple of stills?

-Brad
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Old February 21st, 2008, 05:20 PM   #3
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Look at the footage on a HDTV or something else besides your Mac.
Using the QuickTime player alone makes my HVX footage look VERY noisy. However the same footage played back on a HDTV looks very crisp and clean.
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Old February 21st, 2008, 05:33 PM   #4
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Thanks for the responses. I'd post some stills but it isn't noise like when you gain up which is multi coloured speckles, it's more the green of the brick wall is fizzy.
It's something you can only really see when the image is moving.

Kevin, I'll do that as I'm borrowing the camera again on Monday and will hook the camera up direct to my HDTV and see then.

If it is as you say just a bit of a quicktime issue I'm surprised Panasonic don't warn people about it. The sales people aren't too clued up about the machines they sell and this is something they should make potential buyers aware of so they arent frightened off, it certainly would have done that to me.
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Old February 21st, 2008, 06:46 PM   #5
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The HPX500 like it's little brother the HVX200 uses spatial-offset to take SD chips (the PAL version of the SDX head) up to HD resolution. It is that interpolation process that is responsible for the noise you're seeing. In SD modes, the HPX is so clean, it's scary.

When compared side-to-side in same scene environments the noise characteristics between the F350/355 and HPX500 are near-identical however, because the HPX is shooting in a 4:2:2 color space (XDCAM is 4:2:0) that noise becomes more apparent when viewing on any computer LCD monitor because there is more detail in the original camera signal.

As Kevin noted, when the image is output to a native-resolution screen such as an HDTV monitor the noise simply disappears because these monitors don't have the resolution to pick up that noise - which is the intended purpose for any video camera in that market range - that being a full-sized ENG rig with 2/3" inch 4:2:2 imagers at a budget price.

However, if ultimate image clarity is most important to you, nothing beats either the HPX2000 or 3000 imagers; in comparison to ANY other broadcast-format video camera they have far superior imagery, cleaner still than even the venerable Varicam.
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Old February 21st, 2008, 07:10 PM   #6
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Do you have the final cut gamma box checked in quicktime?
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Old February 22nd, 2008, 01:31 AM   #7
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Quote:
Originally Posted by Kevin Railsback View Post
However the same footage played back on a HDTV looks very crisp and clean.
I concur wholeheartedly. Before going to HPX I did a comparative with a 350 as it had to be competitive. 350 is slighlty better. HPX is much better than HVX. If your shooting Sunrise for Discovery Channel it might make a difference in those big wide landscapes for sure.

Here are settings that I shoot with for a cleaner image
detail -2
v detail +4
detail coring +3

And here is an image that my camera spat out last Sunday on a doco shoot using these settings.
http://www.scarlet-films.com/HPX/TW1.jpg
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Old February 22nd, 2008, 07:30 AM   #8
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Would this noise show up then if it was ever mastered to say a blu ray disc or we did a 35mm transfer for a cinema screen showing?
Is there more noise in HDV?
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Old February 22nd, 2008, 08:25 AM   #9
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Great use of DOF, Noel - good job!

David,

HDV is a video codec and of itself is not "noisy". Noise is strictly a function of how any camera's imagers handle converting analog visual information into a digital bitstream. All cameras have noise characteristics, just as all film has grain, and just like film the higher quality the imagers with better LUX sensitivity, the "lesser" the noise characteristics will be.

Here's the interesting thing that was proved using test signals and scopes; If the F350/355 were shooting the same color-space as the HPX500 you'd see just as much and often more visible noise as the 500. But, since the current crop of XDCAM is using the 4:2:0 color space that last bit of sampling - which is "zero" - simply can't resolve all the noise - or those 2 bits of lost color - that are actually being sent out by the camera imagers.

So in point of fact, the HPX is technically a cleaner imager than the F300 series even at HD resolution but the XDCAM "appears" cleaner because it isn't capturing the full imager bandwidth.

Since Blu-Ray max output resolution is not higher than HDTV spec, which is 1080i you'd never see the noise from the 500 - unless you purposely bumped camera settings to replicate film-grain, which we've done many times rather than create the look in post.
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Old February 22nd, 2008, 09:05 AM   #10
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Could anyone tell me if you get less of this noise at 720p and if messing with the camera settings can drop this noise to a minimum. Does grading the image have an effect on it?
Also is this noise issue more aparrant at night as we are shooting a feature film set entirely in a city at night.
Robert. How much better are the 2000 and 3000 is there practically no noise or is it just a little bit better than the 500.
Also is the noise issue the way it is with HD in general? (except for the super hi-end stuff) I've noticed a fair bit of noise when watching collateral.

Thanks again.
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Old February 22nd, 2008, 09:13 AM   #11
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I also suggest lowering the detail settings to help with noise. There are several scene files that use combinations of gamma curves and knee that also seem to reduce that graininess. After finding a gamma curve and detail setting you like, you can save it into a scene file for later instant recall.

Dave
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Old February 22nd, 2008, 09:28 AM   #12
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Quote:
Originally Posted by David Ellison View Post
Could anyone tell me if you get less of this noise at 720p and if messing with the camera settings can drop this noise to a minimum. Does grading the image have an effect on it?
Also is this noise issue more aparrant at night as we are shooting a feature film set entirely in a city at night.
Robert. How much better are the 2000 and 3000 is there practically no noise or is it just a little bit better than the 500.
Also is the noise issue the way it is with HD in general? (except for the super hi-end stuff) I've noticed a fair bit of noise when watching collateral.

Thanks again.
The thing to keep in mind about *any* video camera is regardless of the manufacturer or what codec they shoot, they are all built around *broadcast* standards (NTSC or PAL), not film production. That means they're not intended for low-light situations nor are they supposed to have the resolution or output capabilities of either film or, a digi-film replacement such as the Viper, F23 or even RED.

What's important to note about night-time shooting whether it's city-scape or not is that all commercial shoots use tons of fill light from massive crane-hung china-balls, to wide-scape HMI's and other tricks of the trade. Unless specified by the writer/producer you'll never see a night-time production using just ambient light (street lights, building or moonlight). So if you're going to shoot anything at night and are hoping that just available light is going to be enough then you'll be sorely disappointed, regardless what camera you use.

So in point of fact, you will see much more visible noise from any video camera in low-light because you'll be forced to either use GAIN or push gamma in post to compensate, and that's never a good thing. Nothing replaces a properly lit scene, and that's the key to good looking imagery, period.

Having said that, the HPX2000 and 3000 imagers are far cleaner than anything else in the *broadcast* camera market, but they still can't make up for the ultra-low LUX situation of a night-time shoot *without* pumping up GAIN. (The 2000 has digital super-GAIN and super-zoom, but these features were specifically designed for ENG crews trying to grab a shot for a news story, NOT for film production).

My advice is to spend your money on obtaining proper lighting for your night-time scenes, once you get that setup you'll be extremely happy with the HPX500.
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