Motion blur issue

[J. C. John]

Hi all, I'm experiencing a terrible motion blur while the subject is moving. The shutter angle was 180 degrees and I was shooting on the Scarlet MX 4K/6:1.
I also shot with 90 degrees and the result was better but the blur was there. I then updated to the latest firmware version, then black shaded and
shot again in my office since I had to get out from the studio with the same results.

By clicking the link below you will be able to download a frame and see how bad the blur is.

If anyone had any similar issues or any idea how to fix the above problem please please advice.

Download link
http://we.tl/3WB67YxX6d

Regards
John

 

[Björn Benckert]

So one frame does not say that much. What was your exposure time / What frame rate where you shooting?

I can not judge how fast the girl is moving, if she moves quickly trough the frame then thats what the motion blur should look like, if she almost stands still then something odd is going on.

So with only one frame it says nothing of the actual motion in the shot. But if you have two frames after each other and something that has constant motion trough the shot it´s quite easy to see what the used shutter angle was.

If you got a lot of quick motion and that kind of full screen greenscreen then I would sugest to go for 90 deg shutter or even less.

 

[Mike Garrick]

A lot of people are shooting slo mo @ 180 then speeding up in post. Works well.

With scarlet MX that would mean shooting @ 3k though.

 

[Björn Benckert]

A lot of people are shooting slo mo @ 180 then speeding up in post. Works well.

With scarlet MX that would mean shooting @ 3k though.

I think his worry is the greenscreen... then such a proach is probably the last thing you want to do. as it brings down resolution and up goes the compression which gives you shitty keys. So better to go for shorter exposure and standard framerate and lowest compression possible. Do 45 deg if you want, if it studders a bit its easy enough to add motion blur in post after you did the key.

 

[Phil Holland]

Some folks shoot green screens with a faster shutter speed/thinner shutter angle to eliminate motion blur and leave it to the compositor to add the motion blur in post.

I am not normally one of those people, but I've been asked to do it a fair amount in my life.

What you are seeing here is standard motion blur. Nothing out of the norm.

 

[J. C. John]

HI guys thanks for your input, I'll upload a shot soon. I was shooting 25FPS and the last time I shot motion on green screen with 180 degrees I had no problems at all. Same studio same set up. I totally agree about 90 or even less degrees shutter angle but I had no problems before.
Thanks!

 

[J. C. John]

Here is the link to the video file. Please have a look and let me know your thoughts.
Thank you!

Download link
http://we.tl/6vBgmLomt3

 

[Patrick Tresch]

It looks natural to me.

Pat

 

[Björn Benckert]

Nothing wrong with that motion blur, looks as should. Don't know what you shot before but as she walks straight trough the frame you get quite a bit of motion. If you look at her feet they move more than a whole instance of themselves in between two frames... then a quarter of that instance is blur at 180 deg shutter. And that is exactly what you have if you look at the attached screen dump with 2 frames mixed with each other.

So my advice is to key it at 4k with a good color setting and then downress to HD or what ever your delivery format is. But you need a very good key to get those feet out nicely and the falloff shadow on the screen will be a bitch.


How much material do you have that is problematic, maybe I can pull the key for you.


Also you know about the rule.. never walk from edge of frame to the other edge faster than 7 seconds... Below that is strobe territory. See RED tools strobe calculator.