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Matt Silvan

Disadvantages with filming 50fps?

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I'm planning to permanently switch my frame rate to 50fps (or 60fps in NTSC).

 

The shutter speed would be 50, 100, or higher accordingly. This is because I would like to have the option to apply slow motion during post production. With the increased number of frames and data available, I hope to smoothen the motion better than a software could, and continue to use a 25fps timeline. Am I missing any drawbacks or disadvantage when using this setting? Is there anything I should mind during filming or post production?

 

Many thanks for your input!

Edited by Matt Silvan

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The only serious problems are increased storage requirements (or poorer image quality due to increased compression) and the stroboscopic motion rendering of a shorter effective shutter speed. The latter can in some cases be repaired with optical flow interpolation, but that's not a practical workflow for all circumstances and you should be certain that you and your clients are OK with the mild short shutter speed look you'll get for shooting 50 for 25.

 

There may be odd flicker issues with certain types of lighting, more than you'd get at 25, but I don't imagine you'd have too many troubles if you shot 50fps in a 50Hz-mains locality.

 

Beyond that as long as you can make your NLE handle it, fine.

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Thanks for your advice, Phil. I definitely have to try it out and test both extensively. My camera would only shoot 50fps at the cost of a lower resolution. Files sizes are approximately similar, though. The picture is darker due to the higher minimum shutter speed, but I'll be careful of any flicker issues as you said.

Edited by Matt Silvan

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Hi guys, 

Glad I found this now, 

Sorry i didn't look before i shot a project in 50fps to edit in 25fps with the Mini Alexa. 

I'm getting this mild short shutter speed look and the director is not liking it

I've tried a few things

 

Adjusting clip speed (using optical interpolation when it's not too heavy movement)

I've made a 50fps sequence and this works the best but the post house won't work with this

I've also re-interpreted the footage but without a lot of progress either. Maybe slightly better though. 

 

Do you have any other ideas?

 

THANK YOU

A

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If you've shot at a shorter shutter angle, there's really not much you can do. The reduced motion blur is going to add a certain amount of shuddering to the image.

There are a couple of bit of software that can attempt to add motion blur back into the image. But they're far from perfect.

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yes it can generate disturbing strobing artefacts if always shooting at 50fps and converting everything to 25. if the camera has rolling shutter it can add to the effect to generate even weirder artefacts which can be very difficult or even impossible to remove. 

I recommend shooting those shots at 25fps which you KNOW you will never do slow motion effects to and the rest of the material can be 50 if you want. 

I mostly work with slow motion material which can be conformed directly to the playback fps and it will never play at normal speed. For example material which is shot 120fps on 50base and then I will just interpret footage it to 24fps before editing. One does not lose ANY image quality that way and it is very simple and fast to do. That workflow is possible because sync sound is rarely needed and the camera sound is not usable if there even is any.

------------------

One of the problems of not knowing what you'll gonna do with the material afterwards is that you will always lose image quality one way or another and will make your post workflow more difficult. By my opinion, you have to know . 

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If you want the option of slow motion, but also need to play in normal speed playback, and you are using a digital camera...

Then set your camera to 50fps (or 60fps) and change the shutter angle to 359 degrees. (or 1/50sec or 1/60sec if that's what appears in your menu).  This way when you play back at 25fps or 30fps the motion blur will appear as normal after discarding every other frame.  If you are considering a 24fps cinema release, use 48fps and 1/48sec exposure per frame.

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