24fps vs 60fps conformed to 24

[Kathy Smith]

Is there any visible difference between a video shot in 24fps vs one shot in 60fps and conformed to 24fps other than the speed/ If I shot something in 24fps and then I shot the same thing in 60fps but much faster and then conformed to 24fps so the speed is roughly the same, is there any other difference in the look of the video?

[Gary Huff]

Yes, you will get the same look that you would get shooting 24fps with a high shutter speed (60p should have a shutter speed of 1/120 or 180 degrees for proper motion rendering).

You might be able to get away with 1/60 and it look okay, which would make the high shutter speed far less apparent, but I would advise testing before using this for anything you wish to conform to slow motion.

[Kathy Smith]

OK, so I can forget about doing this. I was wondering if this would help in eliminating the jutter that's so apparent when panning etc at fat speeds at 24fps

[Gary Huff]

Originally Posted by Kathy Smith

I was wondering if this would help in eliminating the jutter that's so apparent when panning etc at fat speeds at 24fps

Judder is a problem with the frame rate of 24p and the motion characteristics thereof. The only way to eliminate it is to shoot at a higher frame rate. That's why you commonly see sports in 60p or 60i.

[Kathy Smith]

Originally Posted by Gary Huff

Judder is a problem with the frame rate of 24p and the motion characteristics thereof. The only way to eliminate it is to shoot at a higher frame rate. That's why you commonly see sports in 60p or 60i.

right, but I don't like the look of 60p or 60i for non-sport video. What I don't get is how is everyone else dealing with this. When I watch other videos, which I know are not shot 60p or 60i I don't notice the judder, but when I see my footage it's so noticeable. For example, I don't notice any judder in this video.

Hustle + MoVI M5. A Longboard Film on Vimeo

[Gary Huff]

Well, from the look of this video, I highly doubt they were shooting at 1/48 shutter speed. It looks much higher. The motion cadence does not look quite like what I expect for 24p. I would assume shutter was used to compensate for shooting outdoors (definitely how the GoPro does it).

It could have also been shot at a higher frame rate and conformed to 24p without converting it to slow-motion.

But those are your options. Higher frame rate or shutter speed, but you might not like the look of either.

[Kathy Smith]

Originally Posted by Gary Huff

Well, from the look of this video, I highly doubt they were shooting at 1/48 shutter speed. It looks much higher. The motion cadence does not look quite like what I expect for 24p. I would assume shutter was used to compensate for shooting outdoors (definitely how the GoPro does it).

It could have also been shot at a higher frame rate and conformed to 24p without converting it to slow-motion.

But those are your options. Higher frame rate or shutter speed, but you might not like the look of either.

OK, so how do others shoot in 24fps and don't have this problem. I see many videos that do not look like 60p or 60i, have fast motion and are not jittery. What am I doing wrong?

[Kathy Smith]

If you go to this video and watch at 1:44 there is no judder, when I do the same kind of slider shot I get judder

Times Power Of Words - V3 Short on Vimeo

[Seth Bloombaum]

Perhaps that clip is 60i converted to 30p, or original 30p?

[Kathy Smith]

Originally Posted by Seth Bloombaum

Perhaps that clip is 60i converted to 30p, or original 30p?

would 30p look like this? What's the difference between 30p and 60i converted to 30p? The rest of the footage looks 24p, no?

[Seth Bloombaum]

Now that I've clicked over to Vimeo, I see that this piece originated in the UK. It's most likely that it was shot in 25p. Or, less likely, 50i converted to 25p or 24p.

More generally, I have a hard time distinguishing between 30p and 24p unless there are obvious motion artifacts like judder.

Shooting 30p vs. 60i converted to 30p; I'd rather shoot 30p than convert. All online distributions are progressive, and later conversion introduces one more step in the process where things might go fine or maybe not.

To rant on a little, I've not drunk the 24p koolaid. I can certain see and value the more organic look of progressive. And, I really love the look of the current crop of large sensor cameras, dSLRs and the camcorders built on dSLR tech. But my personal feeling is that the motion artifacts of 24p are not a big contributor to filmic aesthetics. I'm more focused on other filmic contributors, like composition, camera movement, lighting, sensor size, grading, etc.

[Gary Huff]

There is still slight judder in that slider shot. Perhaps it's best if you upload the clip you shot that you say has unacceptable judder in it?

[Kathy Smith]

Originally Posted by Gary Huff

There is still slight judder in that slider shot. Perhaps it's best if you upload the clip you shot that you say has unacceptable judder in it?

Sure. Here:

judder - YouTube

[Gary Huff]

Your slider shot is definitely faster than the one from the Power of Words video. If you don't want judder at 24p, the rule of thumb is to pan no faster than seven seconds per image width, i.e. that an object on the far left side of the frame takes seven seconds to travel across the screen to the right side of the frame. Any faster introduces judder.

Higher shutter speeds will help alleviate that somewhat, but will make the motion choppier. So it's a tradeoff.

[Jon Fairhurst]

Another solution is to compose your scenes to distract the viewer from the judder. If you track a person or object of interest, the person will focus there and the background judder won't be noticed. This can be difficult in establishing shots, but there are solutions. (Consider the "feather" at that start and end of Forrest Gump.)

To summarize ways to avoid judder:
* Use slow camera movement (as Gary suggested.)
* Track a foreground image. (Note that with shallow DOF, this might help blur the background, reducing the strobe effect.)
* Whip pan. (Extreme motion swamps the judder, but be careful with rolling shutter skew, which may be more negative than the judder.)
* Use a slower shutter speed. This reduces the strobe effect, but increases blur. This might feel "soupy".
* Find a different solution like a wider shot, jump cut, two camera cut, or rewrite the scene.

An interesting trick for a slider in a nature scene is to use a medium lens, focus on a distant background, and include a foreground object, like a flower, or branch. In this case, the background is sharp and barely moves. The foreground object might move somewhat quickly, but it is blurred due to limited DOF, so it shows no strobe effect. Though the background barely moves, the viewer experiences the camera motion of the slider, due to the foreground motion.

On the other hand, one can use a short shutter interval, move the camera fairly quickly, and embrace the strobe effect a la Saving Private Ryan's Normandy sequence.

BTW, it's possible that DSLRs are more sensitive to judder than is film. Long ago, I did some tests on the 5D2 - before the firmware allowed 24p. (It was 30.0 fps only, which was weird.) My shutter tests showed that light wasn't captured evenly from the start to the end of the shutter period. There was a bit of a spike when the electronic shutter first opened. That means that even with a long shutter period, you'll still get a bit of a sharp ghost in each frame. I have no idea if this is still an issue, or what products might have this issue.

This would mean that if you dislike judder, you might need to double down on your anti-judder strategies. You might pan even slower, insist on foreground objects, or even use more locked down shots.

The solution really depends on the look you seek. As are most things in life, this is a trade off.