GH5 Vlog L and slow motion on the GH5
- Thread starter tokun1
- Start date
If you use the 180 degree rule when shooting VFR at 120fps, you effectively have changed your shutter speed to 1/240. Regardless of the profile used, your going to need a ton of light! You may need even more light because you may be using ETTR to reduce V-Log-L noise.
Thomas Smet
Veteran
Slow motion is complicated to shoot with any camera due to the light requirement and shutter speed. Just the way it is and not much you can do but add a ton of light. A camera like the GH5S has a small advantage since it can look cleaner at higher ISO levels but thats still not a perfect substitute for proper lighting.
Even when you do slow motion in post you should be shooting with a shutter speed that matches your desired speed after rendering in post. For example if you shoot 30p and intend to slow it down to 120p or a 400% slow motion then you still want to shoot that 30p with a 1/240th shutter. You want each frame to have the same reduced amount of motion blur as you would if you were shooting 120p. This way the optical flow has better solid pixels to create new frames. Motion blur is murder for optical flow technology plus if you shot at 120p each frame wouldn't have that same motion blur look anyway.
I say this because you might want to experiment with 30p at 1/240th as a 4k 10bit alternative to doing slow motion with v-log. You may still get some artifacts depending on the complexity of the scene but it would be 4k and 10bit so each frame would have more detail and much better color information with v-log. I suggest 30p vs 24p because the more frames you start with the better. External 60p 10bit would optical flow to 120p almost perfectly since it only needs to create a single in between frame and has much less chance for error. Even if you do get an error it happens in one frame. The larger the gap between frames the more likely creating a new frame will go haywire. The less difference between frames and the less motion blur the more accurate the results will be.
It is the shutter speed that affects how much light you will need however and 1/240th is 1/240th no matter how you do the slow motion or if you just happen to shoot video at 1/240th. 1/240th vs 1/60th is a 2 stop difference so suddenly a f4.0 lens needs to be a f2.0 lens to let in the same amount of light. Or ISO has to bump from 400 to 1600.
Even when you do slow motion in post you should be shooting with a shutter speed that matches your desired speed after rendering in post. For example if you shoot 30p and intend to slow it down to 120p or a 400% slow motion then you still want to shoot that 30p with a 1/240th shutter. You want each frame to have the same reduced amount of motion blur as you would if you were shooting 120p. This way the optical flow has better solid pixels to create new frames. Motion blur is murder for optical flow technology plus if you shot at 120p each frame wouldn't have that same motion blur look anyway.
I say this because you might want to experiment with 30p at 1/240th as a 4k 10bit alternative to doing slow motion with v-log. You may still get some artifacts depending on the complexity of the scene but it would be 4k and 10bit so each frame would have more detail and much better color information with v-log. I suggest 30p vs 24p because the more frames you start with the better. External 60p 10bit would optical flow to 120p almost perfectly since it only needs to create a single in between frame and has much less chance for error. Even if you do get an error it happens in one frame. The larger the gap between frames the more likely creating a new frame will go haywire. The less difference between frames and the less motion blur the more accurate the results will be.
It is the shutter speed that affects how much light you will need however and 1/240th is 1/240th no matter how you do the slow motion or if you just happen to shoot video at 1/240th. 1/240th vs 1/60th is a 2 stop difference so suddenly a f4.0 lens needs to be a f2.0 lens to let in the same amount of light. Or ISO has to bump from 400 to 1600.
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