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Frame Averaging & Dragon

A

Andrew Allsbury

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Does anyone use (2) frame averaging for normal low light scenes on their Dragon? I seem to remember testing this out way back when on MX and not seeing any real improvements, but what I've seen in initial tests with Dragon it seems to greatly reduce noise at high iso. Are there any drawbacks I'm missing?
 
There might be a little bit of weirdness on fast action motion blur (similar to HDRx) but so far in my testing this doesn't look too bad
 
Id always assumed frame averaging was more for timelapse. When shooting at 23.98, how's it different than say a 360 shutter?
 
Nick Morrison said:
Id always assumed frame averaging was more for timelapse. When shooting at 23.98, how's it different than say a 360 shutter?
Click to expand...
Averaging gives you the value "between" the base images. It has the advantage of not influencing brightness like a 360 shutter (or frame combining) would do.

It can be used to reduce noise (other manufacturers implement it as Multi-Shot Noise Reduction), but it only works for areas where there is no change in subject between the base images. So while an averaged image between two images exposed at 1/48th would, in theory, give you the noise like of a image at 1/24th it also gives you the increased motion blur. There are probably gaps between the base images too (not sure about that).

The advantage is, you have the exposure values of an 1/48th image. Everything else... even RED can't beat physics or bend time. ;)

Experimenting with faster shutters, like averaging based on images shot with 1/96th or more, could be interesting. Maybe that gives some slight improvements (in combination with a optimized blackshade).
 
So here is a test we shot today, I would say there is a significant decrease in noise across the image by utilizing Frame Averaging with very little if any negative effects on motion/blur. Not only is there less noise with averaging turned on, but the noise that is present seems to be finer and more organic in its appearance. It would be really great if we could get Graeme's input on whether or not sound could be turned on for frame averaging. This would make frame averaging a great option for low light shooting.

Test was shot on Red Epic Dragon X @ 6KHD 5:1 Compression w/LLO OLPF
ISO was set at 6400 @ f2.8 on Sigma 18-35 Art F1.8 Lens

Quick Video Comparison (In process now)
http://youtu.be/mIfcU4_H79Q

R3D Snapshots
https://drive.google.com/file/d/0B077sOfEkEI2MUJQV1JsQXVOV3c/view?usp=sharing
 
Andrew Allsbury said:
So here is a test we shot today, I would say there is a significant decrease in noise across the image by utilizing Frame Averaging with very little if any negative effects on motion/blur.
Click to expand...
Thanks for sharing. I agree. There is a visible decrease in noise and motion doesn't look broken. However it's not fast motion and there is no camera-movement - you can already see some kind of trailing on the flashlight in the averaged version.
 
I believe statistically speaking this should give you not only half the light of a 360 degree shutter but lower noise than shooting 360 degrees at half the ISO. I'm assuming noise levels are independent of how much light hits a photo site though.
 
Maik, good catch on the flashlight trailing, not sure how I missed that. We will do some more tests and post the results.
 
From scientific view a comparison between 1x1/48th and 2x1/96th (averaged) is probably the most interesting thing - or 1x1/24th vs 2x1/48th. All averaged frames combined should equal the single capture. That makes it comparable, when it comes to the question about noise-reduction.

Comparing 1x1/48th vs 2x1/48th equals shooting 1x24th and that clearly shows less noise.

Still, averaging is a nice tool for motion as it allows staying at a given exposure-level while increasing blur. Thats not just interesting for a fx-look (or stills for sure). It can probably also be used as exposure tool - in some situations it might be able to replace a ND. Instead of shooting 1/48th just shoot 1/96th with 2frame-averaging - half the light but same amount of time/motion.

As for noise-reduction, there is still HDRx. It might end up being the better tool. Example: set your camera to 1/24th, switch preview to the X-track (+1 stop) and expose for this track (which now is set to 1/48th). Thats the way to use HDRx in opposite to the intended usage and track A will deliver a overexposed image (with more blur), which will give you some room for shadow-recovery and noise-reduction in post.
 
Interesting Maik, never thought of using HDRx like that!
 
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