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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Help! - grain in low light conditions

Longer shutter time certainly is a start (max operational is 1/24 sec at the moment, the menu goes down to 1 sec but as of build 15 that doesn't actually work yet). There is quite a bit of variability in the post processing steps too. Try changing exposure in Redcine by separately varying ASA, brightness, and curves, and you will see the dark noise is different in each case.

It can be done... some time ago (a few months?) Jim posted here a frame of the Vegas cityscape at night which looked pretty much noise-free.
 
I don't see how increasing exposure time will help, surely if you do that unless you close down the iris your highlights will just clip to hell. And if you do close iris you're left with the same exposure value and so the black will still be very dark and have to pulled up in post increasing the grain. You can only increase the exposure time in line with the frame rate too, so if shooting at 25fps the maximum exposure time is 1/25th of a second anyway.
Steve
 
Hopefully their will be a high contrast between your highlights and your shadows. If so....you can crush your blacks.
 
If not in a hurry, I'll wait for build 16 in a few weeks. I think it's the kind of thing that will get improvements.
 
May be wrong, but I wouldn't expect Build 16 to be leaps and bounds better in this department, don't see how it can be as you're still using the same sensor, codec etc. I'd expect maybe 5-10% improvement in various areas plus some new enabled features.
Prove me wrong though guys, please!
Steve
 
Steve Phillipps said:
I'd expect maybe 5-10% improvement in various areas plus some new enabled features.
Prove me wrong though guys, please!
Steve
Click to expand...

They are rewriting the codec from the ground up. I can't think of what else the would be trying to improve. Well, they could be improving playback performance... but they've only mentioned image improvements.

Anyway, I've had clean black by crushing them. Also, make sure to render all the way out as the noise reduction in the apps can help.
 
Steve Phillipps said:
I don't see how increasing exposure time will help, surely if you do that unless you close down the iris your highlights will just clip to hell.
Click to expand...

Longer exposure time helps in smoothing out the noise because of the nature / statistics of (many components of) temporal noise (though not all), with the result of increasing your SNR in darker areas. If the highlights are already close to clipping before you started, then it is a problem as you rightly point out. It is not easy to balance both of them together. However, in situations where there is head room for highlights to grow further, longer exposure times is a very effective technique.

Steve Phillipps said:
You can only increase the exposure time in line with the frame rate too, so if shooting at 25fps the maximum exposure time is 1/25th of a second anyway.
Click to expand...

Yes, that is true and puts an upper bound on what you can accomplish when shooting a moving image sequence (film) vs. still image. That is a reason digital still image cameras capture images that are hard to beat by video cameras.
 
Sounds like Post-Production is your best solution here. From all available (and affordable) DeNoise tools around, Neat Image does the best job in removing noise without blurring the image or introducing sharpening artifacts. It's nothing short of amazing. It does take some time though.
You can either use the photoshop plugin and automate it, but I think there's a Neat Video plugin as well.

My first post on these forums, so hello to everyone :)
 
Not that it will help you unless you want B&W images.. But we had a low light situation on a spot that was B&W deliverable. The blacks had a bit of noise and I just seperated the channels in post and used the green channel which was silky. (blue had the most). I then crushed the blacks in color correction. All done on Smoke.
 
jbeale said:
Longer shutter time certainly is a start (max operational is 1/24 sec at the moment, the menu goes down to 1 sec but as of build 15 that doesn't actually work yet).
Click to expand...

This is not actually correct.

Clearly at 24fps you can only achieve a 1/24 sec exposure length.

If you slow down the frame rate via varispeed then you can also lengthen the shutter time.

The ultimate example for instance is a 1fps rate with a shutter speed of 1sec.

In order to achieve this you need to select the relative shutter speed option, then set up your project at 24ps 1/24 sec.

Go into varispeed and dial down the frame rate to 1fps. This will automatically give you an exposure time of 1sec.

You can of course opt to select any shutter speeds to go with your 1fps rate as long as they are equal to or longer than 1sec.

Hope this helps.

Geoff
 
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