Question: What is Fastest Shutter Speed that Gives "Natural" Motion?

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Denniscasey

Well-known member
I know this is one of those "it depends" or "personal preference" questions, but let me give a few parameters: (1) subjects are rapidly moving race cars; (2) objective is to minimize blur of car without making motion appear "unnatural" (i.e. jerky).
This is part of my ongoing quest to do a better job capturing race car action as I become more critical of my previous efforts. Races are few and far between so I have tried experiments filming cars on freeways. However, I think motion is too slow to see differences I would expect. For instance, only setting where motion appeared unnatural to me (panning with cars) was 1080p30 with both 1/60 and 1/500 shutter. Surprisingly to me, 1/500 shutter at both 1080i (60 fields) and 720p60 while panning looked to have natural motion. When I did not pan (cars moving at right angles) car motion was blurry at both shutter speeds (just tried extremes of shutter speed) although individual frames did show much sharper definition at 1/500. I have also experimented on tree leaves blowing in wind (not conclusive) and ceiling fan motion (conclusive that 1/30 blurs more than natural eye sight, 1/250 gave jerky action, but is this a good simulation of race cars with panning??).

I have thought more about forum comments and read more articles essentially about spatial and temporal resolution so understand more about theory of frame rate and shutter speed impact on "sharpness" and "human eye perceived motion." So, theory is getting clearer, but I don't have experience level of forum members and races are few and far (distance) between so chances to experiment are limited. I am going to drive a ways to a race type I don't really care about to do more experiments but would appreciate some guidelines from experiences you may have had--for instance, 1/500 will definitely give impression of jerky motion (maybe I did not see this because of relatively slow speed of cars and way I was panning?). As another example, in Barry's HMC book page 20 it says "for a stuttery/choppy action sequence (..."Saving Private Ryan" effect) try a fast shutter speed such as 1/250 or 1/500."

I know I am just touching one factor (shutter speed) and there are many factors like panning, frame rate, etc that are going to impact tradeoff between "natural" motion and sharpness. If you say definitely 1/500 should not be used, but 1/250 might be used I will not include 1/500 in my range of experiments.

Based on past forum postings as well as additional reading I think I have settled at least on using 720p60 for frame rate (one factor is that my output is Blu-ray discs) so that will be one constant in my range of experiments. Thank you, Dennis
 
I was always taught to double the frame rate.

So if you are shooting at 24fps, than shutter should be 1/48, 30fps - 1/60, 60fps - 1/120, etc...
 
Dennis for sports, if you go 1080 30p or 720 60p I have gone up to 1/500 speed, and if for some reason you see some jerky motion, slow down in post 85 to 90% and will look fine.
The slow convertion will be ideal in Adobe After effects, where you can find special tools more than any other software for slow motion, 85 to 90% is almost no slow motion but you can feel the effect.
 
atarijedi said:
I was always taught to double the frame rate.

So if you are shooting at 24fps, than shutter should be 1/48, 30fps - 1/60, 60fps - 1/120, etc...
Click to expand...

Thank you for feedback. I had read that "rule of thumb" also, but I am finding that filming very fast action like race cars may require some special techniques. Regards, Dennis
 
Felipe Henao said:
Dennis for sports, if you go 1080 30p or 720 60p I have gone up to 1/500 speed, and if for some reason you see some jerky motion, slow down in post 85 to 90% and will look fine.
The slow convertion will be ideal in Adobe After effects, where you can find special tools more than any other software for slow motion, 85 to 90% is almost no slow motion but you can feel the effect.
Click to expand...

Felipe, always appreciate your comments/suggestions. Adjustments in post ( motion effects) adds another tool to work with. At least filming race cars is giving me quite an education in interactions among various camera adjustments (for instance, faster shutter speeds require wider lens openings which in turn can reduce depth of field and so forth). Regards, Dennis
 
Depth of field is on your side with this camera, I wouldn't worry about that, however as you said depending on the camera angle 1/500 could look fine.
 
I notice that 24P tends to be much more sensitive to shutter speed. In general I'd use 180 degree shutter, 1/48 or 1/50. With timelapse, I've found that a 1 frame per second requires a 1/2 second exposure to look natural.

At 30p, higher shutter speeds are more forgiving. Maybe because 24p --> 60p TV has a 3:2 pull-down, but 30p is a 2:2 pull-down. In general, I feel safe up to 1/120 of a second shutter speed.


Bob Diaz
 
BobDiaz said:
I notice that 24P tends to be much more sensitive to shutter speed. In general I'd use 180 degree shutter, 1/48 or 1/50. With timelapse, I've found that a 1 frame per second requires a 1/2 second exposure to look natural.

At 30p, higher shutter speeds are more forgiving. Maybe because 24p --> 60p TV has a 3:2 pull-down, but 30p is a 2:2 pull-down. In general, I feel safe up to 1/120 of a second shutter speed.


Bob Diaz
Click to expand...

Thank you Bob, and you mention yet another important factor I have thought about--the output or viewing format including the good old human eye and way we perceive motion. I read a BBC white paper that was mentioned in another forum where BBC researchers were investigating possibilities if tv standards could go to higher frame rates and the paper of course considered the human element (perception of motion). Here is a link : http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP169.pdf
 
Dennis the very last shot in this video, the one of the bus, was shot at 1/500. Motion looks natural, the one of the ant was 1/250, as well very natural, you can either look the video in full with natural motion
or stop it at any frame and is sharp, I'm not saying Motion blur is bad , is fine but is no the desired effect always.
Take a look and give me your opinion :
http://video.felipehenao.com/Videopaisaje.html
 
What will look "best" will depend on how fast the car is moving across the frame. If you are panning this motion will not be related to how fast the car is actually travelling down the track. (At the extreme, a perfect pan will produce no motion of the car relative to your frame.) So I believe there will be different answers, depending (sorry!) on the extent to which you plan to pan.
 
GrahamH said:
What will look "best" will depend on how fast the car is moving across the frame. If you are panning this motion will not be related to how fast the car is actually travelling down the track. (At the extreme, a perfect pan will produce no motion of the car relative to your frame.) So I believe there will be different answers, depending (sorry!) on the extent to which you plan to pan.
Click to expand...
That is right on the other side if you are a skilful camera man you can pan the car at the right speed to make it look sharp using for example 1/60 speed and the car will look sharp, with a blurry background
 
Felipe, thank you, but did not see this until late and local internet is acting up so not getting good playback. Will try again tomorrow and what I saw looks to be good examples. Regards, Dennis
 
GrahamH said:
What will look "best" will depend on how fast the car is moving across the frame. If you are panning this motion will not be related to how fast the car is actually travelling down the track. (At the extreme, a perfect pan will produce no motion of the car relative to your frame.) So I believe there will be different answers, depending (sorry!) on the extent to which you plan to pan.
Click to expand...

Graham, exactly right and good points regarding panning and in the BBC article I mentioned above they mentioned that some conditions of shutter speed and frame rate could produce nausea in people watching their various experiments when the background and foreground subjects were moving in weird directions. Panning is another area I am working on improving and debating whether fluid head on tripod will help with fast action or not (due to fast panning I expect I will have to have drag pretty much off anyhow). In some cases I have what I try to describe as a "J" shot where I am standing to left of J--cars approach at fast rate along the long part of the J and then turn the corner of the J and head towards me. As they pass in front of me I usually pick a favorite car to pan across with and follow as cars accelerate away from me. In that case I think I need a fast shutter speed to catch the cars moving fast along the long part of the J. When I do it right it is a nice shot, but I am also learning I need to plan ahead to get the right angles for shooting. Still, forum advice is helping my learning and thanks to all. Regards, Dennis
 
Felipe Henao said:
That is right on the other side if you are a skilful camera man you can pan the car at the right speed to make it look sharp using for example 1/60 speed and the car will look sharp, with a blurry background
Click to expand...

Felipe, I agree the best effect is car in sharp focus with background blurred--gives the impression of speed; the skillful part is what is taking time to acquire. At 1/60 and 720p60 my panning efforts still are not good enough to keep car in sharp focus so I was hoping faster shutter speed could help compensate to keep car in sharp detail and not blurred. Regards, Dennis
 
Felipe Henao said:
Dennis the very last shot in this video, the one of the bus, was shot at 1/500. Motion looks natural, the one of the ant was 1/250, as well very natural, you can either look the video in full with natural motion
or stop it at any frame and is sharp, I'm not saying Motion blur is bad , is fine but is no the desired effect always.
Take a look and give me your opinion :
http://video.felipehenao.com/Videopaisaje.html
Click to expand...

Felipe, hooked my "faster" video editing computer up to internet and watched your video. Motion of both the ant and the bus do look "natural." There was one part where ant moved from bottom to top that seemed to skip over some frames so motion seemed too fast in that short bit--but that was probably due to internet video. Both the bus and the tractor wheels were even moving in the "right" direction--I have seen in my experiments that in some cases wheels go "backwards" depending on shutter speed. You had earlier mentioned possibility to adjust motion in post (slow down by 85 or 90%) so curious if you applied that to bus?

Your videos always have great color and definition (understand this is personal taste also, but it is to my taste) and once before you shared your camera settings (saturation, etc. ) and I wonder if you could repeat that--I am having trouble finding your earlier post where you gave settings. Regards, Dennis
 
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