Shutter Speeds vs. FPS

C

cameron12x

Member
I'm a fairly experienced stills shooter, but pretty much an abject beginner when it comes to video. I'm sure there is a lot more to it, but for starters I just need a couple of tips on shutter speed usage. Some quick questions:

If you're shooting 30fps, the minimum required shutter speed should be 1/30th second (or faster)?

Are there problems (e.g. jitter) shooting at too high of a shutter speed? (e.g. 30 fps at 1/500th, for example)?

Are there "optimal" shutter speeds to use at various fps settings?

In full-frame still photography, there is a general rule to minmally shoot at the reciprocal of the lens focal length (e.g. 100mm lens = 1/100th second) or faster to eliminate motion blur. Is there an analog in video shooting, or does this no longer matter? Thanks in advance!
 
The shutter depends on what you plan to do with your footage. If slow motion and shot at 60 fps minimum shutter 60 max 120.Higher shutter will give you jerky slo mo motion. Should shoot everything in manual and even in manual mode and if you are filming 60 fps the camera will not let you set the shutter below 60.
 
If you're shooting video, leave the shutter on 1/50th for 24p, and 1/60th for 720/60p, unless you have a very good reason for changing it.

This isn't still photography; shutter setting is not used to control exposure in video (unless you really have no other choice). Use ND filters and the iris to control exposure, but don't go changing the shutter speed because it changes the perception of motion.
 
I haven't tried the 7d, but concerning shooting video(hmc-151) I find the best shutter for slomo to be 1/120 shutter, as the 1/60th will bring too much motion blur. Like one would on film, shouldn't one try to make the "gaps" between each exposed frame after you slowed down the 50p footage to 25fps to be the same as recorded 25p played back at 25fps?

I'm no specialist, just curious :)
 
Barry_Green said:
If you're shooting video, leave the shutter on 1/50th for 24p, and 1/60th for 720/60p, unless you have a very good reason for changing it.

This isn't still photography; shutter setting is not used to control exposure in video (unless you really have no other choice). Use ND filters and the iris to control exposure, but don't go changing the shutter speed because it changes the perception of motion.
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Thanks! This is exactly the kind of information which I was hoping to find.

Just curious, why 1/60th for 720/60p? What effects would 1/125th have at this setting?
 
cameron12x said:
Just curious, why 1/60th for 720/60p? What effects would 1/125th have at this setting?
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If you plan on slowing down the 60p to 24 or 30 then you'd want to have it at 1/125th. In motion picture terms, the shutter speed is referred to as the shutter angle. The "normal" shutter angle that most people use is 180 degrees, which is what everyone is suggesting that you use. That basically means that the shutter speed is double the speed of the frame rate (ie: 24 fps at 1/48th second, 30 fps at 1/60th, 60 fps at 1/120th). A higher shutter angle, lets say 360, (ie: 24 fps at 1/24th second, 30 fps at 1/30th and so on) which is the highest you could possibly go on some cameras results in a blurred smeared effect from movement. A lower shutter angle like 110 degrees (ie: 24 fps at 1/80th, 30 fps at 1/100th, etc.) results in motion that's more sharp, strobelike, and frantic. A famous example of that is the D-Day scene in Saving Private Ryan.

Basically you need to be aware that when you move away from a 180 degree shutter, it changes the look of the motion in the image. I'd suggest going out and practicing to become familiar with this. You shouldn't be scared of changing the shutter angle as it can be a very useful tool, but you do need to be careful, especially when shooting at lower shutter angles (remember, that's higher shutter speeds), because this camera is capable of some absurdly low shutter angles.
 
Are we talking in terms of angle or in terms of time the image is shown? If 180 degree shutter contributes to "film look" more than seeing an image for 1/48-th of a second, then shooting 60i or 60p with 1/120 shutter should look more "filmic" than with 1/60, is this correct? This does not seem to be true to me. It seems to me that too slow shutter speed results in smear, too fast speed results in staccato look. It just happened that 1/48 looks good for a human eye and for 24p it constitutes 180 degrees. This does not mean that 180 degrees will always look good or "filmic" (filmic is good?). I am missing something? Should we be better off (human perception-wise) talking in terms of seconds rather than in terms of angles?
 
Cranky said:
Are we talking in terms of angle or in terms of time the image is shown? If 180 degree shutter contributes to "film look" more than seeing an image for 1/48-th of a second, then shooting 60i or 60p with 1/120 shutter should look more "filmic" than with 1/60, is this correct? This does not seem to be true to me. It seems to me that too slow shutter speed results in smear, too fast speed results in staccato look. It just happened that 1/48 looks good for a human eye and for 24p it constitutes 180 degrees. This does not mean that 180 degrees will always look good or "filmic" (filmic is good?). I am missing something? Should we be better off (human perception-wise) talking in terms of seconds rather than in terms of angles?
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I think you're overthinking this. Film plays at 24 fps. period. If you play back anything at a different frame rate it won't really look like what we're used to seeing projected in movie theaters. Playing anything at 60 fps will look very video like regardless of your shutter speed. But if you take that 60 fps and play it back at 24 fps then it becomes filmic.

The reason why we talk in terms of angles is that we assume that everything will end up playing at 24 fps. This might help you: http://en.wikipedia.org/wiki/Rotary_disc_shutter
 
The angle moves with the frame rate, so when shooting 24fps, a 180-degree angle gives you 1/48th exposure, and when shooting 60fps, a 180-degree angle gives you 1/120th exposure.

If you're wanting to use your 60fps footage as slow-motion in a 24p project, then sticking with the angle will preserve a film-like exposure and film-like motion blur.

If you're wanting to use your 60fps footage as 60fps (i.e., the "live video look") then you'd want a set fixed 1/60th exposure.
 
This topic also begs the question: when will we get, or is it possible to give, a 1/48 on these cameras? Specifically for Video?
 
Just wonder why it hasn't been included seeing as how this definitely isn't the first generation of hybrid. As well, the rest of the digital motion picture-centric shutter speeds.

Barry, do you know if the 1/50th @ 24p will cause any issues or oddities with transfers to any other media/medium? Film print especially.
 
Barry_Green said:
The angle moves with the frame rate, so when shooting 24fps, a 180-degree angle gives you 1/48th exposure, and when shooting 60fps, a 180-degree angle gives you 1/120th exposure.
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I know that, thanks.

Barry_Green said:
If you're wanting to use your 60fps footage as slow-motion in a 24p project, then sticking with the angle will preserve a film-like exposure and film-like motion blur.
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This follows from the prior statement.

Barry_Green said:
If you're wanting to use your 60fps footage as 60fps (i.e., the "live video look") then you'd want a set fixed 1/60th exposure.
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1/60 to 60fps means 360 degree shutter in film terms, but 360 degree shutter for 24p does not look like video (I know that it is not at all possible to shoot with 360 degree shutter on a real movie cam, so say it is a 350 degree shutter, close enough). It just seems that anything above say 1/40 and below say 1/100 produces image that is not too smeary and not too staccato, that is, organic to human eye. This is my question, why being so hung up onto the angle, when the actual exposure time is what really matters? Talking in angles makes sense only for over/under-cranking, but then again on a real movie camera you have to do nothing, you just roll the film faster or slower and the shutter speed depends on the angle and on the shooting frame rate, it is all mechanically related. When projecting with constant speed you get the same motion across the film. On a digital camera shutter speed has no relation to shooting frame rate and there is no mechanical shutter, so talking in terms of angle makes no practical sense to me. It just fogs the subject, making the shutter angle the more important contributor to film look or any other look, than actual shutter speed.
 
Cranky said:
On a digital camera shutter speed has no relation to shooting frame rate and there is no mechanical shutter, so talking in terms of angle makes no practical sense to me. It just fogs the subject, making the shutter angle the more important contributor to film look or any other look, than actual shutter speed.
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Yeah, you can call it whatever you want as long as the people you are communicating with understand what you mean. Coming from the HVX, which had a mode that allowed you to adjust the "shutter angle", I'm just used to talking in terms of shutter angles. Now I'm moving back to talking in terms of shutter speeds when I shoot with a 7d. Really the purpose of bringing shutter angle into the conversation was to help explain the relationship between shutter speed and frame rate, which I believe was the goal of this thread.
 
dvollrath said:
Really the purpose of bringing shutter angle into the conversation was to help explain the relationship between shutter speed and frame rate
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But there is no relationship between shutter speed and frame rate when you shoot with a digital camera. My original rant/question was that if 180 degree shutter is proper for 24p for creating film look, then creating a similar look when shooting 60fps would involve using 1/120 shutter. True or not? Apparently, display frame rate (smoothness vs. stutter) and actual shutter speed (smear vs. staccato) is more important than a holdover from the mechanical past.
 
Kholi said:
Barry, do you know if the 1/50th @ 24p will cause any issues or oddities with transfers to any other media/medium? Film print especially.
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Why would it cause problems? It's nearly identical to 1/48th, and film cameras exist that use anywhere from about 1/43 to 1/80th second as default shutter speeds, so ... should be no issue.

The only issue at all that I can think of that 1/50 (or 1/48) will cause is the HMI/fluorescent scrolling waves phenomenon. For that reason alone I say most people would probably be better off to just go with 1/60th and forget about it.
 
Cranky said:
1/60 to 60fps means 360 degree shutter in film terms, but 360 degree shutter for 24p does not look like video
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Correct. It just looks like a blurry smear.

It just seems that anything above say 1/40 and below say 1/100 produces image that is not too smeary and not too staccato, that is, organic to human eye.
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Agreed. People obsess over getting *exactly* 180 degrees, or *exactly* 1/48, and it largely doesn't matter. I've owned dozens of movie cameras over the years, with shutter angles ranging from 90 to 220 degrees. Granted 90 degrees is staccato, and 220 is a little smeary, but in general, anywhere from 1/43 to 1/60 is gonna look filmlike.

This is my question, why being so hung up onto the angle, when the actual exposure time is what really matters? Talking in angles makes sense only for over/under-cranking, but then again on a real movie camera you have to do nothing, you just roll the film faster or slower and the shutter speed depends on the angle and on the shooting frame rate, it is all mechanically related. When projecting with constant speed you get the same motion across the film. On a digital camera shutter speed has no relation to shooting frame rate and there is no mechanical shutter, so talking in terms of angle makes no practical sense to me.
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But your premise, while being correct for some cameras (that don't have shutter angle as an option), is also incorrect (for those that do have it). It depends on the camera you're talking about. Any of the HVX200/HPX170/HPX500/HPX300 series uses "shutter angle" as an individual setting that tracks with the frame rate, exactly like it does on a movie camera. The EX1/EX3 have some limited shutter angle capabilities as well. Having the angle option is what allows these cameras to track with the frame rate. If you stuck the shutter on 1/60 and went to shoot some overcranking, you'd find it too blurry. If you stuck the shutter on 180 degrees and went to do overcranking, you'd find that the camera adjusted for you and it'd all just work, just like on the mechanical film camera.

The shutter speed is what the angle controls. It's not that the angle is more important than the shutter speed, it's that the shutter angle dictates what the actual shutter speed will be.
 
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Cranky said:
But there is no relationship between shutter speed and frame rate when you shoot with a digital camera.
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And here is where you are wrong. There are many cameras that have the exact same relationship.

My original rant/question was that if 180 degree shutter is proper for 24p for creating film look, then creating a similar look when shooting 60fps would involve using 1/120 shutter. True or not?
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True.
 
Barry, I understand that the angle controls the shutter speed. But for varicams this is just a convenience. Basically, you select your target projection frame ratio, which can be either 24, 30 or 60 fps, and you select your basic shutter speed (in seconds) with the premise that the video is shot with the same frame rate as it will be projected. Then you convert this shutter speed to an angle so that you would not have to change actual shutter speed every time you over/under-crank. This is just a convenience feature, you could as well re-set shutter speed every time you shoot overcranked video, just a bit more calculations to do.

Thanks for confirming that actual angle does not have to be exact 180 degrees.

Still, if you think of it, action is shot at faster actual shutter speed when you overcrank, so I am not sure why it would look the same when you project it with slower rate. The actual image has been shot with fast shutter hence it is recorded sharper than normal images, and if subject moves fast, you will see more strobing. Um, this means that to achieve the same look of strobing subject has to move slower in proportion to overcranked speed. If you do 200% overcrank then the subject must move twice slower to produce the same strobing as normal shooting. Am I right?
 
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