BMCC problem. Heavy noise at ASA800 and lines across the screen!

[Adrian Sierkowski]

800 ASA gives you the full spread of the dynamic range of the sensor; so the theory goes, which is why they pick it as the "native" ISO. Bringing it down to 400 would then sacrifice 1 stop Dynamic range generally in the highlights. There was a very big thing about this back on the red when it first came out-- not same camera, obviously, but similar idea.

Personally I keep my pocket @ 800; but that's just me.

I don't think you'll find too much of a problem with the noise.

 

That's off a pocket @800 we used as an insert camera to an alexa; also @ 800. Best example i have on my desktop at the moment. no grading done, minus using the same LUT as the Alexa (LogC-REC)

It's off of an 8bit h.264 I have, if you notice the banding as I do. Noise was pretty similar to the Alexa on the whole.

[Tyler Purcell]

Huh interesting…. I'll have to do some tests! :)

[yobeju]

Hi everybody,

 

when i shoot (with my bmcc), every ISO settings (form 200 to 1600) give a noise:

 

Exemple here with Canon 50mm 1.8 lens:

 

f/2.8 ISO 200

Blackmagic Cinema Camera_200.dng - 4.8 MB

 

f/2.8 ISO 400

Blackmagic Cinema Camera_400.dng - 4.8 MB

 

f/2.8 ISO 800

Blackmagic Cinema Camera_800.dng - 4.8 MB

 

f/2.8 ISO 1600

Blackmagic Cinema Camera_1600.dng - 4.8 MB

 

The noise is on the grey (of iMac) and the white wall (behind the cat). Is it normal ?

 

Sorry for my english.

Edited March 22, 2015 by yobeju

[John E Clark]

Hi everybody,

 

when i shoot (with my bmcc), every ISO settings (form 200 to 1600) give a noise:

 

Exemple here with Canon 50mm 1.8 lens:

 

f/2.8 ISO 200

Blackmagic Cinema Camera_200.dng - 4.8 MB

 

The noise is on the grey (of iMac) and the white wall (behind the cat). Is it normal ?

 

Sorry for my english.

 

 

I overcame my intense dislike for 'cheap' download sites that require waiting and 'captcha' access to view your images. In general, for most purposes of discussion on fora like this, a JPEG image on a 'easily viewable' site, say Flickr, or similar, would be best for discussing.

 

Sometimes for larger media, like 'motion picture' in MOV or whatever format, then maybe a transfer site, even 'free' transfer site loaded with advertisements, may be in order.

 

In any case, from looking at the ISO 200 image... it is 'way' under exposed. I'd say by at least 3 stops, of not 4.

 

When the curves are applied to show a reasonable light to dark range, noise in the low values will be 'enhanced'.

 

Set the exposure for ISO 200 such that the 'white' walls are in the proper range, that would be about 80-90% IRE and the 'noise' you may find should be minimal, and only found in the dark cat figure, and probably not that objectionable, since there will be more detail/texture/surface lighting rather than either blank black, or dark regions, as is the case now.

[Steve Howe]

I'm confused.. 800ASA looks like crap. So you're saying that's what the camera is SUPPOSE to look like?

 

I looked at your vimeo and your interiors look way under lit. I'm not surprised you're not impressed with your images. Are you using any lighting apart from practicals?

[Vadim Joy]

Your images are underexposed. It's your fault.

Steve even when underexposed it should be black, or grainy. It shouldn't show sensor lines.

[Vadim Joy]

He posted candle light images as proof of his problem. Candlelight is massively under exposing - of course you're going to get FPN under those conditions. My BMCC gives FPN under those conditions. Manufacturers often replace boards to placate customers.

I know how FPN looks like, and this is definitely not a noise.

[Carlos Gottberath]

If your BMCC shows lines in the Footage regardless of the ISO Setting its definitely not behaving like it should. I had the same Issue, shooting a Fashion Show, slightly underexposed @ISO 800 at Parts because of the constantly changing Show Lighting. For my relief i could get rid of most of it in the Grade. But I send the Cam straight back to Blackmagic, they told me it was a Sensor Problem with FPN and sent me a new one Back. My new one has a noisefree, sharp and clean Image on all ISOs!

[Tyler Purcell]

I looked at your vimeo and your interiors look way under lit. I'm not surprised you're not impressed with your images. Are you using any lighting apart from practicals?

Yep, that's the only reason you'd use 800 ASA in my book. When you can light things properly, you'd be up around 400 or even 200 ASA. A lot of times, I show up to shoots during the day, thinking I can shoot outside and something happens. I don't bring lights with me all the time, so I have to figure out a way to use practices 90% of the time. I keep a few small lighting accessories with me in my camera bag, just incase. Sometimes I screw up and the practical lighting sucks, but other times it comes out pretty darn good. I'll be honest, a lot of my stuff on Vimeo is me messing around with the camera, learning how to make it work right, rather then serious production work.

[Will Montgomery]

When you can light things properly, you'd be up around 400 or even 200 ASA.

I was at one of these seminars where they bring in DPs to talk about what they do and this had a workshop. They were shooting in almost no light, looking at a monitor and making subtle adjustments in light position until they were happy with what they saw on screen.

 

I thought, well you must be pushing the sensitivity almost as far as it goes and must mean lots of noise in the blacks. I said why don't you keep the same ratio but just double the light and tweak when coloring it? He looked at me like I had two heads.

 

Colorists I work with constantly tell me, "when you have the light the way you like it, double it." That's coming from working with film and I know I can get low-light looks with more light. As colorists also say, you can take away light easy, it's adding that's hard (in post).

 

I appreciate the idea of getting it right in camera and I guess that changes from film to digital, but this trend of seeing how little light you can possibly use seems counter productive to me...try using more light and using lower ASAs to reduce noise (on cameras that this makes sense with) and spending a little more time in Resolve. You'll wind up with a sharper, cleaner image with the same "look" if you do it right.

 

Just my 2 cents.

[David Mullen ASC]

As for why not just double the light level, that's fine if you have the lights and the power, but keep in mind that it's not exactly the same look IF you are balancing to existing low-level sources like candles, city street lamps at night, late twilight, a location with dim existing practicals, etc. But otherwise, I agree that if you can use a 300w for a key light, why not use a 650w instead, it takes just as much time to set-up either.

[Tyler Purcell]

I personally don't like the 'low light look' it's really bothersome. Filmmakers use it all the time and it's just silly. Good DP's can make a low-light look out of anything; super bright day or super well-lit interior. I've used that look many times over my life and never really liked it, looks too amateurish. I'm very much a "what's in camera is on screen" sorta filmmaker.

[David Mullen ASC]

Again, it's about BALANCE, sometimes you need to get more exposure out of something in the frame that is naturally dim and have to balance to that. I shot a scene in a penthouse (with tinted windows) in Manhattan looking out at the Empire State Building for "Smash" and had to work at T/2.0 at 1250 ASA with a 240 degree shutter to get the city background to read well.

 

 

(ignore the French subtitles, the show only came out in blu-ray in France... and they burned-in French subtitles for all the singing they couldn't dub into French)

 

 

But when you are not balancing against something, then sometimes it makes more sense to work at a decent stop.

[Tyler Purcell]

Yep, agreed. Balance is important, especially if you care about everything within each shot. A lot of filmmakers don't, over exposing or underexposing areas that aren't important.

[Will Montgomery]

Thanks David, good point about balancing when you have fixed light sources. And I guess in the case I described there may have been a lamp light at the end of the couch that would have to be accounted for. I know its hard to discuss without specific examples.

 

Would I be correct to say that if that scene didn't have the windows and candles (much less interesting for sure) you could have shot at an optimal ASA for your camera and adjusted the lights, T stop and shutter to give you a similar look with less chance for noise in the blacks?

 

I'm guessing that the answer is that experience (which you have in abundance) dictates what variable you change and how you change it; lighting, aperture & asa (film or digital) change based on infinite artistic variables (like depth of field).

 

The only rule of thumb I can think of would be maybe to err on the side of more light when artistically possible to keep your colorist happy.

[David Mullen ASC]

You have a lot of factors to weigh because there are always practical limitations to deal with, so it becomes hard to be too generalized about best practices. For example, there is an old rule that most lenses are best closed two-stops down from wide-open, but if you have to shoot on T/2.8 zooms, you may not be able to light everything to T/5.6 or even want to.

 

There is a point where it becomes harder to maintain a natural look with the lighting for night interiors if you have to use really high light levels. It's not impossible as all the lovely interior work of the 1970's movies show, shot on 100 ASA film, but you have to weigh the effort against the results, at which point are you working too hard for a minimal improvement. That's sort of a judgement call.

 

But yes, in the abstract, once you know the optimal ASA setting for noise that is also practical for your work, and an f-stop setting that is also practical for your work, you would tend to light for that. I'm always a bit surprised when someone goes out and shoots a whole project and then complains that the noise is too high when he views the results... when spending an afternoon with the camera in prep - especially if he then took the footage to a color-correction suite - would have helped avoid unpleasant surprises. Of course, we all get bit now and then, you can't test for every scenario.

 

It's partly an issue about information -- sometimes more exposure gives you more information to work with, sometimes not (if you end up clipping something important.) But you also have to please yourself artistically, it's not about making a colorist happy by giving them too much information to play with, it's more about going in with footage that does not need to be "saved" by the colorist because it's the extreme adjustments that usually generate artifacts.