motion blur film vs video look

R

Ruairi Robinson

Member
Hey, haven't seen Apocolypto yet, but from the trailers and the clips I've seen, it seems that every time the camera moves fast, it starts to look like VIDEO.

So my question is - if this because of the shutter angle being too low, leading to a smeary, over motion blurred video look, or is there some other technical explanation. I've heard some talk previously here about shutter angles, and I can't claim to be an expert, but I know what I LIKE.

And with the red camera, will we be able to change the shutter angle.

And will it avoid that ugly smeary video look...?
 
Ruairi Robinson said:
And with the red camera, will we be able to change the shutter angle.
Click to expand...

The Red camera has an elecronic shutter, not a mechanical one. This means that you can change the shutter speed (the electronic equivalent of shutter angle) beyond the range that would be possible with a mechanical shutter. So you can have as much or as little motion blur as you like.
 
The Genesis has an electronic shutter as well.
The smear could come from a lot of sources.
Either it could be larger shutter angle to get up to a stop more exposure in the deep woods.
It could also be that the trailer has been cut in an app which uses motion vectors to speed up and slow down. Such an app can make the unusual motion blur as well if the shots are modified.
 
Looking at the trailer, there are quite a few shots in it with frame blended speed changes. These can indeed often look a bit 'smeary'.

Nick
 
Nick_Shaw said:
Looking at the trailer, there are quite a few shots in it with frame blended speed changes. These can indeed often look a bit 'smeary'.

Nick
Click to expand...
Smeary look, could it be due to high frame rates (e.g., 60Hz), the vertical rolling electronics/mechanical shuttering, or both?
 
Apocalypto was shot on a Genesis, so would primarily have been shot at 24p. The Genesis does not go up to 60Hz. The cameras used when they started shooting Apocalypto could only do 30fps, but they got updated cameras later during the shoot which could do 50fps.

None of this should cause excessive motion blur, unless the shutter was set to 360 degree equivalent (ie 24th of a second shutter at 24 fps) either intentionally as an effect, or as Anders said in order to gain an extra stop of exposure.

Nick
 
There was a long discusion about shutter speed over at dvinfo. Here:

http://www.dvinfo.net/conf/showthread.php?t=76426&page=3

Lots of technical stuff about image tearing & mechanical shutter vs. rolling shutter vs. global shutter... Bottom line is that Red is using a new system that is quite different from the Genesis, F950, Viper, etc.

What matters much more than the technical method & specs is how the images look. In that respect I was worried about the reverse - that RED seemed to have a bit LESS motion blur (narrow shutter angle) than what I'm used to seeing on an Arri film camera at 180 degree shutter (most folks seem to want to match the film look).

Ideally (perhaps when Spike is ready) RED can shoot side-by-side comparison tests with the Mysterium vs. Arri or Panavision. Stuff like whip-panning the camera back and forth, waving a hand in front of lens, people running, etc. My impression is that the good folks at RED are all over this and will deliver great results. :)
 
Nick_Shaw said:
Apocalypto was shot on a Genesis, so would primarily have been shot at 24p. The Genesis does not go up to 60Hz. The cameras used when they started shooting Apocalypto could only do 30fps, but they got updated cameras later during the shoot which could do 50fps.

None of this should cause excessive motion blur, unless the shutter was set to 360 degree equivalent (ie 24th of a second shutter at 24 fps) either intentionally as an effect, or as Anders said in order to gain an extra stop of exposure.

Nick
Click to expand...
So vertical rolling shutter cannot cause image smearing?
 
No, rolling shutter just causes vertival lines to slant, when they move in the the horisontal direction. Motion blur is the same per pixel as Global shutter with the same shutterspeed. It's just a small readout delay from line to line.
 
For clarity, here are some of Jim's comments from this thread:
http://www.dvinfo.net/conf/showthread.php?t=76426&page=3

I hope it's cool to post them here:
_______

"Our sensor is designed in a different way than you are used to seeing.... the electronic shutter can't be described, exactly, in terms you have been using for past designs. Test shots coming will show the results of the Mysterium® sensor in a variety of situations, including what you have been asking for.

Not trying to be vague, just not ready to give away all secrets quite yet. What it looks like is more important than the method we use.

Jim."
_______

"... we do not use our CMOS the same way it has been done in the past. It is a fairly ingenious design that I'm sure others will catch up to in the future... barring patent infringement.

When you see the actual sensor, you will quickly see that it is not like any you have seen before. Current designs on the market can not do what our sensor does- spec-wise. That is by design. It really is a new sheet of paper program. Not just hype.

We have some flexibility that other CMOS designs cannot offer. We can generate different "looks" depending on how we set the sensor up. We are testing now to decide which "look" we want to lock down.

Jim"
_____

"People hold a "film look" in high esteem. It "feels" right. That "look" includes a few anomalies, like 24 frames a second (instead of a "now" looking 60 fps), grain and a motion handling "tear" from a mechanical shutter. People have been begging for this look instead of a Betacam video look. We are striving to provide the "feel" experience with the RED ONE. After all, it is a digital cinema camera. If you want a harsh broadcast video look, I suggest you shoot 60fps or buy a video camera and save some money.

Jim"
_____

"So far, we have found an incrediblly beautiful look. As we post more samples you can decide for yourself if you need to "doctor up" the image at all. We think that most will love what comes our the camera and onto your screen.

Jim"
_____

"There is so much mis-information around about "rolling shutters" and "global shutters" that I want to make sure we are talking about the look and not technology terms. 35mm film has tearing, which comes from the mechanical shutter. We are deciding how much we want to look like a film camera vs. a CCD video camera that shoots 24p vs. a DSLR vs. a new look that we can provide. That's why we are really listening. We want you to be happy with the images, whatever the jargon is.

Jim"
_____
 
Anders Holck said:
No, rolling shutter just causes vertival lines to slant, when they move in the the horisontal direction. Motion blur is the same per pixel as Global shutter with the same shutterspeed. It's just a small readout delay from line to line.
Click to expand...
Thank you, as I always get confuse. Will slanting effect helps to make motion images look more natural than you would get with no slanting as in Global Shuttering though?
 
Motion blur dissuses the edges, so the slanting is less obvious. A higher shutterspeed will make it more obvious, as motion blur is decreased.

The amount of slanting is a constant of the readout time per line. Shutterspeed wnot affect it.
Raising the data bus frequency will lower the time it takes to send the line, and by that lower the slant.
Also doubling the framerate can help.
Instead of doing 24 fps at 180 degrees, you can do 48 fps at 360 degrees and drop every other frme
Remember. Most of the really bad examples of this effect is from small CMOS imagers, mostly Industrial types.
These effects dont really apply to more mature products.
 
Anders,

- So by increasing the frame rates, the data readout line frequency will have to be increase too?

- By increasing the frame rates then the shutter speed will also increases?
 
From what I understand, a lot of the night scenes in Apocalypto were pushed two stops and shot with a 360º shutter...so their motion rendering may be kind of iffy.

The trailer looks fine to me, though. Very pretty.
 
All i know is that apocalypto looked like shiit. So bad that it appeared interlaced...and I dearly hope that it was. If not...then I have my doubts about digital filmmaking.Though I thought the motion for genesis on Superman was good...so I think it has to be a setting adjustment.
 
A 360 shutter will produce a kind of video look. If you pick a nearer 180 shutter, the result will be much more like film, even if you keep the fps at 24 in both cases.

Graeme
 
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