Flexible framerate feature idea

[Noah Yuan-Vogel]

I still think It would be worthwhile to implement flexible framerates/shutterspeed in REDs new DSMCs. Seems like it would be possible to have a camera mode where it always shoots at 120fps with an open shutter and then select the frame rate you want to use in redcine which is stored in metadata for the decoder to use on playback.

from 120fps 1/120th shutter material, one could potentially use frame dropping and/or blending (open shutter material should ostensibly have no space between the motion blur of consecutive frames, so blending two 120fps frames would potentially create almost the same frame that would have occurred in 60fps shooting) to create material with other common frame-rates or shutter speeds (120,60,40,30,24,20,etc fps and 1/120,60,40,30,24,20,etc shutters) .

I've attached a diagram to illustrate. Obviously higher starting framerates would allow more framerate and shutter options (1/48th shutter for example), but 120fps is the lowest speed that allows real 24fps and 60fps simultaneously from the same material.

This would be yet another way to give the maximum flexibility in post, and no one else has this that I know of. And this would be one (two actually, fps and shutter) less decision to worry about on set.

I thought of this idea quite a while ago but seems like RED is the only company that would have any chance at implementing this given their hardware and workflow and knack for actually listening to customer's requests.

 

[Tim Sutherland]

But once you shoot with 360 degree shutter, you have so much motion blur that you can't really get back. I think if you wanted this feature, you could just shoot 120fps as it is now and do all that in post. I don't think it would really come out as clean as most people would like. You'd be much better off shooting 24fps when you want and 60fps when you want high speed.

 

[jetaddiction]

sorry tim but 360 degree at 120 frame rate is 1/120 shutter speed . maybe your thinking 360 degree at 1/24 ,ya, lots of motion blur . hence the degree refernce only works when you know how fast the frames are flying by. this setting would not have much motion blur at all. ( reg shooting). cool concept.

 

[Tim Sutherland]

sorry tim but 360 degree at 120 frame rate is 1/120 shutter speed . maybe your thinking 360 degree at 1/24 ,ya, lots of motion blur . hence the degree refernce only works when you know how fast the frames are flying by. this setting would not have much motion blur at all. ( reg shooting). cool concept.

That's what I get for posting first thing in the morning. Major brain fart.

This method could only work well in well-lit situations since 1/120 shutter at 320ISO is pretty slow. Especially when using tungsten light and trying to keep the blue channel noise-free.

If you have this mode, it would have to work more like the Vaircam 'flagged frames' mode so that you wouldn't have to re-interpret the footage in your editing system.

 

[Noah Yuan-Vogel]

Yes but it could also contribute to much cleaner images when used in particular ways. Frame blending (for the conversions that use it) would significantly lower the noise floor and increase usable dynamic range. Noise occurs per captured frame so combining frames would cancel out a lot of noise and increase usable dynamic range.

I think that if handled correctly in software it might even be possible to expose for 24fps 1/48th and end up with 24fps 1/40th (closest supported shutter when capturing at 120fps) footage that is even cleaner and higher latitude than you wouldve gotten shooting at 24fps normally. It definitely would be an interesting thing to explore.

Underexposing 120fps footage would mean more highlight latitude and less shadow latitude, but it would be interesting to see if the effect of frame blending on the noise floor is great enough to make up for the shadow latitude lost to underexposure, and if so, whether then re-exposing for a higher software gain in post (as RED does it) recovers the shadows without any noise penalty over normal shooting. If so, the whole process might even leave you with some extra highlight latitude for free. This might be a ludicrous idea, but it's just a thought. Obviously its really hard for me to say, but someone else might have an idea of the actual tradeoffs of such a workflow, and It would certainly be worth testing.

Maybe that doesnt make sense at all and it would be best to just always expose for 1/120th second shutter since that would render more useable footage for all framerate and shutter post options.

 

[Douglas Underdahl]

Well I think you could grab a RED One right now and do some tests? Shoot 120 fps and try different extractions in post.

 

[Noah Yuan-Vogel]

I certainly would if I had access to a RED ONE. That's why I posted here rather than did tests myself. Of course this might be better suited to a Scarlet 2/3" or any other upcoming camera can shoot its full frame at 120fps. RED ONE would be limited to its ROI 2K mode, which makes it much less attractive for that camera.

Do people even think this feature would be worth looking into? Am I crazy to think this is a great idea that RED should spend time working on for their new cameras?