For a project, I want make a car look like it's going faster than it is, and I thought I would speed it up somewhat in post, and add motion blur.

I researched more on doing this and some sources say to shoot at a high frame rate, like 60 fps or more, because that will make the fast motion look smoother. Where as others say to shoot in regular 24 fps and just take out what frames you need to in post.

However, if 60 fps would look smoother, and I wanted to cut it down to 18 fps in post, would 60 fps really make a difference in smoothness if 42 frames per second are taken out?

It doesn't look like there is much difference to me whether it was originally shot in 24 fps or 60, if all there is, is 18 fps in the end. Unless I am wrong?

I've never tried shooting at 60 fps for this making cars go faster, although I've shot at a slower frame rate, the latter being the standard method in westerns for horses.

The downside is that if you want a car to look like it's going fast, you need to drive a car fast, because the dynamics change with speed. That's why they close off road for filming this stuff, for you budget level I wouldn't put too much weight on high speed car shots for dramatic effect unless you've got a stunt driver(s) and access to closed/private roads.

For really scary stuff nothing beats the Class B rally cars

Rally Group B - Tribute - YouTube

As an aside, in the days of the 55 MPH speed in the US, it was amusing to see a shot of the speedo reading 70 MPH to indicate speed. That was the speed limit in the UK at the time, so wasn't that impressive.

Oh okay, but is possible to lower the frame rate to make a car look like it's going faster though? I was watching the making of The French Connection and they talked about how the car chase shots are at 18 fps, to make the car look like it's going faster. So could I therefore, cut it down to 18 fps successfully?

Yes, but the car in the French Connection (I assume in the subway train chase) was already going fast. It just sharpens things up a bit, I've shot 18fps at normal car speeds and you wouldn't notice much difference.

The French Connection (4/5) Movie CLIP - Chasing the Train (1971) HD - YouTube

Given our urban speed limit of 30mph. a car would appear to be going 7.5mph faster. It's not high speed chase stuff and quite a few cars do 33 to 35mph normally, so you do need more speed and use maneuvers that give the impression of speed.

Oh okay sure, thanks. But I thought I would still take out some frames to sharpen it up a bit if that helps. When you say you shot 18 fps, does that mean you had access to a digital camera than can shoot at 18 fps?

I cannot find a camera that goes under 23.976 fps. I tried some tests on mine with magic lantern, and took it down to 6 fps, but it stops recording after a couple of seconds. But would anything under 18 fps be too much fast motion?

This was using a film camera.

Oh okay. Well one person I asked said that when you speed up objects, you should shoot at a high frame rate like 120 fps he says, cause that makes speeding up to fast motion look smoother. But if you are going to cut it down to 18 frames, does it really make a difference shooting in 120 fps, if all you have is 18 fps left in edit?

You won't have as much image blur if you shoot at 120 fps because of the faster shutter speed (you"ll need to ass it in post). It sounds like someone is puling your leg. It'll only be smoother if you are plat back in slow motion. it's the reason why 32fps or 36fps are used, because of the very slight slow motion that smooths things out when okayed at the standard 24dos,

Not although you'll be using it, but I gather the Arri Alexa can shoot at lower frame rates,

Yeah okay, I think the vfx person I talked to was confused and was applying the high framerate method when it comes to fast motion, when he was probably thinking slow motion. Or maybe he thought it would be good for both.

So if I want fast motion then in post, there is no reason to shoot over 23.976 fps then?

No, shooting at your standard frame rate will be fine.

Okay. Well I took a test shot of some motorcycles and speeded it up in post, with different settings, but which one looks more convincing?

motorcycle speed test 4 - YouTube

motorcycle speed test 3 - YouTube

It's be the speeded background action that gives it away. You need to test the same action as in your film, if your shots just consist of motor bikes zipping through the frame, that fine but it it doesn't prove your action for say cars driving towards you or going around a corner.

I thought they both look 'messed with'.
https://youtu.be/WTj-jJDkYkM
This looks like he's riding really fast, but I suspect it's not, and the sound of the bike high revving completes the illusion. Naked skin flesh, as in without helmet ripples above 40mph, as any biker knows too well. In the final shot, the low angle makes it look faster - I bet the scene didn't break wind!

Oh okay. well what about The French Connection car chase for example where they undercrank to 18 fps... How do they make it look good and not make it looked 'messed with'?

In The French Connection they are already driving fast. To them, the thing to beat was the car chase in Bullet

Are you going to be able to drive the vehicles faster than the urban speed limit?

No I won't be able to drive faster than the speed limit.

You are going to need to not just undercrank, but your camera movements must be also slowed down and smoothed, because objects behave differently when sped up. The other thing is consider what the reduced frame rate does to the actual video. The car/bike will move further between frames. The slower free rate will also blur the image. How much is experimentation again. Let's say you want to make a car at 30mph look like it is doing 60mph. Your options are to underzrank, and speed up in the editor - this will give you motion blur, and more changes between frames. Alternatively you can shoot at say 60fps and have razor sharp images that have little difference between frames, and then you speed this up in the edit, which probably means throwing frames away. Again a different look. Try it and see what looks best.

Oh okay, well I have tried both and it seems to me that shooting at a higher frame rate is worse, because their is not as much motion blur, and you need more motion blur to make undercranking look better.

That is what I think so far, from what I can tell. Would you concur with that? Plus if I shoot at 60 and speed it up in the edit to 18 fps, I am still throwing away 42 frames. So what good is 60 fps, if 42 frames are now gone? How does that make 60 fps smoother?

As for moving the camera slower, I still have to keep up with the car though. So if I want to pan with the car, I have to move the camera fast enough to keep up in the pan, don't I?

I know you have an obsession about steady pictures, but doing "grabbed" handheld shots combined with fast cutting is probably the way to go. This is because you're not going to have the dramatics of a high speed chase with cars that look like they're doing 37 mph (shooting at 18fps) with the camera stuck on a tripod.

The cars in the Bourne video weren't going fast, but it looks a lot more exciting than if the same shots were done from a tripod.

Oh okay, well I wasn't planning on having all the car shots be on a tripod, but I thought some of the establishing ones should be.

What is it about handheld that makes a car look like it's going faster?

Also, when you say do tests at 60 fps, to see how sharper they are, do you mean with the shutter speed set at 1/60, or more like 1/120?

It's a combination of things, shooting tighter shots, barely being able to keep things in frame because things are happening so fast, good fast cutting, You need to create the impression that these cars are doing 50 or 60mph in city streets and you can't keep up with what's happening. Spielberg vibrated cameras etc in the opening of Saving Private Ryan on the D Day landings..

I've hard mounted a camera inside a saloon racing car on a race track and it didn't give any impression of the G forces involved, it just looked like a quiet drive down the country.

Okay sure. As long as barely being able to keep things in the frame doesn't look sloppy.

One idea I had was this would be a good time to use the telephoto lens on a tripod, cause if you zoom in and pan with the car, the compression will give the car the appearance that it is going faster, because objects in the background will pass by quicker, as the car drives. Is this what you mean by shooting tighter shots as well? But I can mix those shots with other wider shots from the front and rear of the car, since the wide lenses of course, will make it look like it's going faster from the front and rear.

Plus I also watched this video on making a car looking like it's going fast:

DJI Film School - Car Chase - YouTube

And at 3:42 in the video, he says that he speeded up the footage in post, but that if you do that, you need to shoot very smoothly, so the speeding up in post doesn't look jittery. So if I shot it so that I can barely keep the car in the frame, wouldn't that look jittery if you speed up in post, compared to keeping it frame more smoothly then, or no? But he also said he was able to speed up the shots 'a lot' as he put it, so how did he do that without it looking sped up and made it look more natural?

You can speed things up a lot as long as you don't have anything else in the frame that's moving and the car is going in a straight line. Going around corners things change and it starts to look fake.

They're tracking with the car, which is a lot more dynamic than a camera on a tripod panning with a telephoto lens, which is pretty televisual these days, since Ir's a motor sport standard shot.

Oh okay thanks, this helps a lot. Also, when speeding things up, I added motion blur in my tests, but I noticed that there doesn't seem to be any added motion blur in that film riot example. Is not adding motion blur better, for trying to make a vehicle look like it's going faster?

You used more motion blur than you'd see in reality.

Oh okay, I tried estimating. In one example I used 180 degree shutter angel setting and in the other, I used a 90 degree shutter setting. Should I go lower than 90 even?

Use according to taste.

Well I want to use the amount which is natural since you said it was not natural looking to have that much before. I can keep playing around with it...

he speeded up the footage in post, but that if you do that, you need to shoot very smoothly, so the speeding up in post doesn't look jittery.
That's what I meant about smoothness - any jerky movement from the camera is enhanced.

That clip was full of useful stuff for you Ryan. The problem you're having is that you're experiments are somewhat random. You mentioned that if the subject falls out of frame that doesn't matter? It does - that's just bad camerawork. Framing is always win/lose.

The thing is really that what the viewer uses to assess speed is quite variable. In a 4x4 racing across a field, then sharpness with the violent movements because of the ground indicates exactly what's happening - the violence and bouncing is a positive. The shot contains the clues and is exciting. If you go to F1 races then the fact they are doing 200mph does not come across. When we first started broadcasting live races on modern cameras people said they looked slower, because the cameras captured sharper pictures without the old two frame low res interlaced blurry pics, and for a while broadcasters tried to use slower frame rates, or other tweaks to recreate the old fashioned 'fast' look, and it pretty much failed. Now we just have sharp images and have gotten used to it!

Of course you also have the background tricks - so you have nice sharp objects, with the camera following, that lets the background blur out - that's a good one. Or you have the static shot as you put up, but proper motion blur is less pleasant or successful.

So many things to try and get used to.

Oh okay, what I meant was, is that it was said before in this post, to barely keep things in frame in order to sell the illusion of speed:

It's a combination of things, shooting tighter shots, barely being able to keep things in frame because things are happening so fast, good fast cutting, You need to create the impression that these cars are doing 50 or 60mph in city streets and you can't keep up with what's happening. Spielberg vibrated cameras etc in the opening of Saving Private Ryan on the D Day landings..

I've hard mounted a camera inside a saloon racing car on a race track and it didn't give any impression of the G forces involved, it just looked like a quiet drive down the country.

But the video says to keep things smooth, which seems like opposite advice. So I was just wondering if one is better than the other, if they seem like opposite advice, that's all.

They can also be used in combination, depending on the action.

If you're pushing things to limit shot framing wise, you need to have an extremely good editor. otherwise it looks terrible.

Sure, I can use both methods smooth steady shots that are sped up, cut along with more frantic framing shots, that are not sped up, but more quick cut...