Lamplighter55
Captain
Flight distance : 538596 ft
United Kingdom
Offline
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compunerd3 Posted at 2-9 15:52
Thanks for the advice, I mentioned in my post above that I did try the camera settings you suggested, lower ISO, higher ISO, also tried Auto, multiple shutter speeds and also ND filters. It's happening on any footage, green, sand, water, anything. It's been happening on footage I checked as far back as August also.
Yup the camera has a bandwidth limit in order to encode the video at 4K. We hit that limit when the subject matter being filmed has a lot of high frequency (small high contrast detail) over large areas of the field of view. This added to the low light noise floor of the camera capture chip increases the bandwidth requirement of the amount of discrete data coming off the camera chip from frame to frame. There's some on (or near) camera processing that tries to reduce that data by buffering 8 frame segments and reducing the refresh/buffer flushes and resamples to every 8th frame for areas of the frame that are relatively low contrast. You can see this effect on panning shots with a lot of green/brown grass or with cloud structures in the upper portion of the frame. Setting the Sharpness to 1 and the frame rate to 25 helps mitigate that as it forces full frame resamples for every frame. I always have my settings at ISO 100 fps 25 and shutter 1/50 (using the standard 180 degree cinema camera rule - frame rate is half the shutter speed). I've not tried it but one way to reduce the spatial noise is to sample the footage down from 4K to 1080p in your edit - using an area averaging filter. I use Neat Video Denoise (https://www.neatvideo.com) for important footage - but costs money and is slow to process for long sections of aerial drone footage. |
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