Help Needed, excessive noise in images

Segarza

Segarza

Well-known member
I know this topic has been dealt with quite a couple of times in the forum, however I haven't found any definitive workaround (if there actually is any).

I'm in preproduction for a very *important* corporate video (the company is rated the third most profitable business in Mexico during 2003, funny they didn't approve the HD or 35mm budget). So I've been testing the dvx's scene settings, and have gotten more than satisfactory results for most scenarios, except one (or two): sunrises and sunsets.

I figure that at some point during the production, I'd like to shoot a sunrise or sunset (maybe even a time lapse, clouds, etc.) with the silhouette of an industrial plant in the foreground.

However I'm getting excessive noise in near-dark gray areas, such as dark clouds, even sky. I've tried fooling (no real methodology, just going on hunches) with the settings and so far this has worked best:
Detail Coring: +7
Gamma: B. Press
Matrix: Normal
Master Ped: -10

However I still find it to be excessively noisy. Do you guys have any suggestions?

I love to use ND grads and color grads, now I'm having second thoughts on using them because they could end up producing noisy clouds or sky, etc.

I'm choosing the DVX for aesthetical reasons (motion wise, 24 fps). However, we have a DSR-300 package available as well, which I used to shoot side by side with the DVX100A (sunsets, sunrises), and obviously (for $7k more) no noise. I'm seriously considering on dropping the DVX and shooting 60i, then possibly converting to 30p or even 24p.

Any suggestions for reducing noise? (how about grain removal in post? has anyone tried this on DV25 footage?)

Thanks
 
Re: Help Needed, excessive noise in images

You can usually get rid of most noise in post by a simple curves adjustment.
 
Re: Help Needed, excessive noise in images

If you want to compare the basic noise performance (S/N ratio) of different cams, just record some footage with closed lenscap and +12db gain or higher if both cams have higher gain up settings. Compare the visible noise.
 
Re: Help Needed, excessive noise in images

More than comparing, I would like to know if anyone has found any optimal settings, or if anyone tried the 85 filter solution and white balancing through it.

Any suggestions are very very welcome.

Thanks!
 
Re: Help Needed, excessive noise in images

I went ahead and conducted the following test:

Iris: Closed
Progressive: 24p
Shutter: 1/48
Gamma: Norm
Matrix: Norm
Everything else: 0
Gain: +12dB

Tested both 3200 Preset and 5600 Preset, and 3200 has a much much much better S/N. So you WILL actually get cleaner images if you use the 3200 preset and use a 85B filter in front of your lens.
 
Re: Help Needed, excessive noise in images

Further testing showed the following:

If you decide not to go for the 85B filter solution for exteriors,
shooting:
Gamma: B.Press
Matrix: Norm
VDetail: Thin (Mid is significantly noisier)

Will give you the least noise under 5600 preset.

Again, this test was conducted with a closed iris, 12db gain, and everything else at 0.

Hope this helps.
 
Re: Help Needed, excessive noise in images

Heh I know I'm talking to myself here, however I hope these findings help anyone out there suffering from the same problem.

Well, I didn't have a 85B handy but I did have some Rosco Full CTO left overs ;) There is a huge improvement shooting with the 3200K preset and a 5500->3200K filter, and of course using the settings above.

As soon as I get my 85B 4x4 I'll post some comparison stills.

I'm definitely shooting this video with the DVX100A now that this issue has been solved (partially anyways).

Special thanks to andre and every user in the forum, without your support and info I'd never would've how to start looking for a solution.
 
Re: Help Needed, excessive noise in images

Salvador, I appreciate you posting this information. I'm going to test out my 85 tomorrow outside as well. It's about time I took it out of the box.
 
Re: Help Needed, excessive noise in images

Salvador,

Are you suggesting outdoors to use an 85 filter with the 3200k WB factory preset without manually white balancing?

I would assume if you shot outdoors and manually white balanced, no factory preset, without the 85, it would be just like shooting with the 5600k factory WB preset or pretty close. So manually white balancing outdoors with no 85 filter to get near the 5600k level would be adding noise.

This weekend I am going to shoot an image outdoors with the 5600 WB factory preset then shoot the same image with the 3200 WB factory preset while using my 85 filter. I think my 3x3" 85 is just an "85" not "85b" so the results may be a bit cooler than with the 85b. I think I made sense:-)
 
Re: Help Needed, excessive noise in images

No prob! It'll make time spent testing worthwhile if this gets out and results in other dvx users getting better images.

On a clear day yep, I'd definitely go for 85B+3200K preset (superb low noise results). On a cloudy day, I'd probably use 85B + manual balance. Diffusion makes a light source cooler. I have yet to test manual balancing and see how it affects noise. However while testing I tried ATW with the iris completely closed and 12dB gain, and there was considerable amount of noise, compared with 3200K preset. I am not sure if this proves anything, aside from stay away from ATW, which I suppose most of us do.

And yes, white balancing in exteriors without a 85B filter, will actually result in a noisier image (if the actual scene has any content that falls below certain level).

Yep you got it! :D
 
Re: Help Needed, excessive noise in images

That's an awesome discovery, as I was too worried sick about the noise... Thanks for the experiments, they were extremely helpful!

Cheers!
 
Re: Help Needed, excessive noise in images

Salvador,

I didn't have much time this morning but I do think that the 85 filter does help a bit along with the previous settings you posted. I do need to get an 85b, the 85 does make thinks, especially whites, a bit cooler with the 3200k preset. Gamma, Matrix, etc. are all the combination for adding noise in "certain darker areas" of the image, not all. I did discover that the Quicktime Codec is also one of the culprits of the noise, it needs an update by Apple, I think one will come soon. Before digitizing into FCP, I watched my footage and it was a tad less noisier in areas before the transfer. All in all, the DVX100a takes fantastic images, I am more than pleased with this camera and in coimbination with the Magic Bullet software, the results are endless. This camera is still hard to beat in my opinion, the XL2 looks good but almost double the size and weight and in some of the examples I've seen so far, it still produces that "Canon Blur" I call it and I've experienced with my previous XL1 and XL1s, everyone has their preference though. I want to try out that 55mm 4.0 plug-in as well, did you purchase it or are you trying out the demo? Take care.
 
Re: Help Needed, excessive noise in images

You'll notice significant improvements on certain subjects, for example dark clouds, etc. Remember noise was most apparent in near dark areas.

This testing was motivated by unsuccessful attempts at recording nice and clean sunsets and sunrises, where noise practically dominated the image. I've seen a huge improvement in those types of images.

At this moment I wouldn't even think of buying an XL2, not after it's been tested for a while, and maybe even an XL2A hehehe is released ;)

I bought the 55mm 4.0, and I find them to be extremely useful.
 
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