Blackmagic Forum

If I shoot at 120fps or up to 300fps and above is it an idea to think of other shutter angles rather than sticking to the 180 degree rule?

I haven't tried but would using a 90 degree shutter be a good idea?

I have a feeling in the back of my mind that a smaller shutter angle (quicker shutter) will help to give a better image when the footage is put onto a 25fps timeline.

This is just a hunch because I can't find anything on YouTube to back this up. My thought is that as the frame rate is so high then I want to reduce camera blur a bit so that when the footage is slowed down to 25fps it looks a bit more sharp rather than a smudge moving at slow speed.

Am I barking up the wrong tree and got my understanding of Sutter Angles completely wrong for high speed filming?

If you like the look of motion blur at 25/30fps which all use 180° shutter angle, then if you double the frame-rate you should double the shutter angle as well. So for 50/60fps the shutter angle would be 360°

I'd say it's a subjective decision, and you also got to take the amount of light into consideration. Higher frame rates may force you into 360 degrees if the light is low.
For aesthetics, I'd try things out, it will be just different looks.

Edwin Street wrote:If you like the look of motion blur at 25/30fps which all use 180° shutter angle, then if you double the frame-rate you should double the shutter angle as well. So for 50/60fps the shutter angle would be 360°

This is where I’m concerned. If I chose a 360 degree shutter rule for high frame rates like 120fps or 300fps and then put the footage on a 25fps timeline, wouldn’t I be looking at a blurry image that may be mistaken for poor focusing?

If I shot at 90 degrees I’m hoping that there would be less motion blur so that when I put the footage into a 25fps timeline it would look clearer with more detail.

You have less motion blur even with a 180deg shutter because the frame rate is higher..ergo the shutter speed is higher too.

Everyone is used to seeing 180 deg shutter in most narrative context and it’s the same for higher frame rate material.

I personally don’t change the shutter angle no matter the frame rate unless there’s an emotional or storytelling reason to do so.

JB

When shooting some wildlife - birds in particular - I typically just use shutter speed instead, setting to something like 1/2000 sec. This way if I change from 60 fps to 120 fps my exposure stays constant. The speed can be determined by how much motion to stop. (of course, there needs to be enough light as the lens I use opens to f4.)

The 12K shutter speed can be set up to 1/5000 sec. This seems to work but still puzzles me because in super16 - 6K the sensor scan rate is 7.78ms which would seem to be about 1/128.53 sec. But tested going from 1/125 - 1/250 - 1/500 - 1/1000 - 1/2000 - 1/4000 the exposure changes in appropriate stops and the motion reduced as expected. So does the scan rate impact shutter speed??? It does not seem to.

The sensor readout limits the frames per second, not the exposure. so 120 fps is the limit. But you can use various shutter angles/speeds within that limit subject to having a large enough aperture or fast enough ISO.

With rolling shutter cams the exposure time is for each line which is then read sequentially. The rolling shutter interval does determine the max theoretical frame rate.

Good Luck