VRay movie cam vs still cam - Exposure and Motionblur

[Morne]

Hi all

Is there some kind of formula to match exposure and motion blur of the movie cam to a still cam?

I'm liking the exposure of my still cam, but I'm liking the motionblur of my movie cam

Alternatively on my still cam I can up my F stop and change my shutter to keep exposure and increase motion blur. I always use the still cam even for animation so I'm just experimenting with the movie cam to see if there is ANY benefit. So I guess what I'm really asking is if the motion blur calculations is the same under the hood for these 2 type of cams (forgetting for a moment the exposure)

[vlado]

Yes, motion blur is the same.

Best regards,
Vlado

[Morne]

Yes, motion blur is the same.

Best regards,
Vlado

So then what formula can I use for my still cam to match the motion blur of the movie cam when shutter angle is 180 degrees?

[vlado]

It depends on your frame rate. If you have 24 fps, then 180 degrees shutter is 1/2 of 1/24th of a second, or 1/48th of a second.

Best regards,
Vlado

[Morne]

nevermind
just set shutter speed to 1/48

[Morne]

It depends on your frame rate. If you have 24 fps, then 180 degrees shutter is 1/2 of 1/24th of a second, or 1/48th of a second.

Best regards,
Vlado

we were typing the same time

[AbeMata]

Compiled a list a while back. They work the same. You can check it yourself, of course. Here are some equivalents:

Physical Cam (movie)
shutterAngle: 360
shutterOffset: 0
Standard Cam
Duration: 1
IntCenter: 0.5

Physical Cam (movie)
shutterAngle: 180
shutterOffset: 90
Standard Cam
Duration: 0.5
IntCenter: 0.5

Physical Cam (movie)
shutterAngle: 180
shutterOffset: -90
Standard Cam
Duration: 0.5
IntCenter: 0

Physical Cam (movie)
shutterAngle: 180
shutterOffset: 180
Standard Cam
Duration: 0.5
IntCenter: 1.0

[Morne]

OK I tried couple of frames with the 180 Shutter Angle/Equivalent 1/48 shutter speed for "film" 24 frames/second

At framerate 24, it looks almost asif the blur is a bit too much for the speed my cam is going past some trees. At a framerate of 30 however, this looks awesome.
(3dsMax framerate is set to film - 24 frames/sec, but I tested playback at 30 frames with my player)

I know its all artistic and I should just adjust things till it looks good. My point is, wasn't 1/48 suppose to work great for a framerate of 24 frames/sec?

[Neilg]

I know its all artistic and I should just adjust things till it looks good. My point is, wasn't 1/48 suppose to work great for a framerate of 24 frames/sec?

No, 1/48 is just .5 of a frame - that's the biggest you can possibly go with a mechanical film camera.
whatever works best is a stylistic choice - If nothing is moving too fast i'd use .5 of a frame, if there's constant fast motion then I prefer to go lower. Most films are shot lower.
Saving private ryan famously used really low shutter angles - something like 45degrees (1/200) so there was hardly any motion blur and it's a big part of how it looks the way it does.

watch this -
https://www.youtube.com/watch?v=xn1mpszEjZM

[Morne]

The point of the exercise was to simulate a cinematic film camera
With the "converted" numbers, the motion blur seems too strong