Grain without gain… what a pain!

[Scott Sheriff]

Science!
Low light environs don’t saturate the pickup sufficiently. What you are seeing is noise caused random electron movement in the pickup. This is made worse by heat generated by the cameras circuits. The warmer the camera gets, the noisier it will be.
Sub zero gain is really for bright shooting situations when you have to much DOF and can’t add any more ND. I would go with more gain, not less. I think the noise from the extra gain is less intrusive, than the dark noise from the pickup.

Scott Sheriff
Director
SST Digital Media
https://www.sstdigitalmedia.com

[Thomas Morter-laing]

So what you’re effectively saying is that in conditions such as these, a small amount of gain (eg +3db) may actually HELP the situation- if thats the case then you’re by extension suggesting a possible time to use gain for real broadcast work? (I still dont understand why they build cameras able to use 18db- anything needing that would look TERRIBLE anyway…)

And just to confirm, all the negative gain does is reduce exposure digitally, rather than actually reduce noise as well? (I know it makes it darker, just wondering if there were any other hidden benefits to it…)

😀
Tom Morter-Laing
Certified Apple Product Proffessional, 2010
Degree; TV Production

iMac 27″ intel i7 2.93GHz, 12GB RAM, ATI HD5750 [1GB GDDR5], 2TB Int. SATA with 2TB External HDD; (FW800).

[Dylan Hargreaves]

“I still dont understand why they build cameras able to use 18db- anything needing that would look TERRIBLE anyway…”

Yes, it does. But there are times when it’s your only option. Obviously it’s not ideal and in any kind of controlled environment would be unacceptable, but I can think of several documentaries/reality shows where the camera has unexpectedly had to film outside in the middle of the night.

If the toss-up is between grainy pictures showing something or black pictures showing nothing, I think most times, the audience will accept some pretty high noise levels on the footage.

On that subject, it might seriously be worth investigating the DSLR route for low light filming in the future. Our shoot yesterday ran longer than anticipated, (the client’s fault I should add) and my humble 550D dug us out of a right hole – an unbelievable and beautiful image using street lighting alone. Awesome for a £900 investment – and I ain’t no DSLR fanboy either!

[Bj Ahlen]

[Dylan Hargreaves] “”I still dont understand why they build cameras able to use 18db- anything needing that would look TERRIBLE anyway…””

Not on a 2/3″ camera.

But they have less random sensor noise to amplify together with the good signal. It’s all about the signal/noise ratio which doesn’t change when you amplify both.

For grainy/noisy footage, Topaz Enhance for FCP/AE can create wonders. They have a 30-day unlimited trial so you can test with your footage.

[I have no connection with Topaz other than as a very satisfied customer of several of their plug-ins.]

[Scott Sheriff]

“So what you’re effectively saying is that in conditions such as these, a small amount of gain (eg +3db) may actually HELP the situation- if thats the case then you’re by extension suggesting a possible time to use gain for real broadcast work? (I still dont understand why they build cameras able to use 18db- anything needing that would look TERRIBLE anyway…)”

+3db is only 1 stop, so that isn’t a lot of gain. No one but you is even going to notice.
Broadcasters routinely use gain all the time, even with the new modern digital gear. A place its used a lot is ENG work, and sports remotes.
Back in the old days when I worked for one of those 3 letter broadcasters, we would use as much gain as we had to on tube cameras, because it wasn’t always possible to get enough light, or if we needed more DoF. Those cameras usually topped out at +9. Saticon tubes, at +9. Now that my friend, is a grainy image!
When the chip cameras came out they had +12, or even +18, and we used that if we had to. We really didn’t fear the gain switch. It was more important to come back with the shot, and there isn’t much level you can get out of underexposed footage in post, at least in analog NTSC.
On new digital cameras, a lot depends on how your going to deliver. If the final is going to big screen, or projection, I might worry more about grain. But for small screen, the audience probably doesn’t even notice, if your story has got their attention.
Another thing you have going for you in digital, is there is a bit more level boost you can do in post, maybe two stops. So that means you either have to have enough light, or gain to get within two stops. If circumstances wouldn’t let me add more light, and it took +9 (or more) to got me into that zone, I would do it, rather than be down in the mud. Under and over exposed footage both suffer from information loss which at some point, can’t be recovered in post. So I think grain reduction plugins work better on grain, than on dark noise.

“And just to confirm, all the negative gain does is reduce exposure digitally, rather than actually reduce noise as well? (I know it makes it darker, just wondering if there were any other hidden benefits to it…)”

Yes, negative gain is something you use to reduce exposure, like using ND. So if your cam has a -3db setting, that cuts the exposure by a stop. This will not reduce ‘dark noise’ caused by underexposing the image sensor.
What you have to understand about image sensors is they have an inherent noise floor, which shouldn’t be confused with grain caused by using the gain switch. This noise (think of it like visual room tone) can only be overcome by getting enough exposure. You have to find the Goldilocks balance between gain and dark noise.

In the end these things are all just tools. They all have a place, and shouldn’t be feared, with the exception of anything marked ‘auto’. Be happy, don’t worry. If you have to use a little gain to get your shot, go ahead.

Scott Sheriff
Director
SST Digital Media
https://www.sstdigitalmedia.com

[Phil Balsdon]

Neat Video does an excellent job of reducing gain noise in these situations.
https://www.neatvideo.com/

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
https://www.steadi-onfilms.com.au/