Shutter Speeds - What Do You Use?

As seen in IPVM's Average Frame Rate Used post, the average frame rate used by integrators is anywhere from 6 - 10 FPS.

One question that was not answered, however, is the shutter speed used to accomodate frame rates. It should be known that default frame rates tend to vary across manufacturers, and this is a large problem in low light, as some cameras default to a slow shutter (1/5 or 1/15) at night.

That being said, what is the average shutter speed you use for your cameras, and why do you use it? For LPC and LPR applications, what shutter is used there? Have you used a slow shutter before with or without knowing, and if so, what were the ramifications, if any?

Background - Shutter Speed / Exposure Tutorial, Shutter vs Frame Rate, Camera Slow Shutter / Ghosting Tested


Mostly 1/30 or 1/60. Occasionally higher for very bright scenes but never lower than 1/30. And always, always, always disable slow shutter :-(

Bravo for a great question. I think outdoor camera shutter speed is an underrated setting! Ironic that most camera installations are done during the day, yest the usually most important video is taken from night shots.

Also especially important because low quality camera manufacturers often ship their cameras with a default speed of 1/5 (to make their cameras look better).

(And for the record, I agree with the above response)

Are there any guidelines in surveillence for setting the frame rate optimally if the shutter speed is known or vice versa?

In videography, the 'holy grail' is shutter speed set to double the frame rate. Though this harkens back to mechanical rotary shutters, it apparently gives a natural amount of motion blur.

One question, everybody bags on motion-blur, but aren't there conceivable situations where a high shutter speed is actually too fast, not because of exposure, but rather because the shutter obscures something? Because at a SS of 1/1000 sec with a frame rate of 10, you are not 'watching' 99% of the time! And anything that can happen within 100ms, has a good chance of being missed. Whereas at SS 1/10 and 10 fps, although it might have blur you can see something happened, and which way it was last headed...

Rukmini,

I haven't noticed that, on analog or MP IP cameras. From my observations, setting shutter speed at, say, 1/1000 with, say, 30fps frame rate still yields 30 distinct images a second. That would be the limiting factor. One could state that high-speed motion would be "frozen" by the shutter, even at 30fps whereas a 1/30 shutter speed would yield a blurred representation of the entire 1/30s but I can't see what good that would do, except perhaps if you want to see the entire arc of the wakeup slap given to the purveyor of supercilious questions :-))

From my observations, setting shutter speed at, say, 1/1000 with, say, 30fps frame rate still yields 30 distinct images a second.

We agree. This is hard to argue with at any shutter speed (equal to or faster than the frame rate, at least). On the other hand, I mentioned 10fps in my example specifically for two reasons

  1. It was the upper range from the survey.
  2. 1,10,100,1000 are easy operands.

For the reasons above and because it was the actual number used in my premise (the same premise which unleashed the wake-up slap) I am reverting to the original, of 10fps. If you insist upon your modification of 30fps, I will entertain it, but I think it only fair that you recall the slap... Proceeding we have:

One could state that high-speed motion would be "frozen" by the shutter...

But, one would be wrong, since

10 fps = 1 frame per 100 millisecond

And therefore you have 10 frames every second, each recording only 1 millisecond of action each frame and leaving 99 ms of action lost forever. So if an object (a thrown yellow $1000 chip, or gun) comes in and out of frame faster than 1/10 of a second, you might get a frame with it in there and you might not!

Whereas with 10fps and a SS of 1/10, you would least have 10 streaks of yellow blur, moving progressively across the FOV, indicating at least the direction in which the item might be recovered, as well as confirming its existence.

Finally, if in your defense you must resort to testimonial and anecdotal rhetoric, I understand, but at least dismantle my logical thinking first, if you can. Take my word, it will give your trusty 'argument from experience' much more force if it were actually to be used in support of a rational position.

Yeah fine. Then I would agree with John. Up the frame rate...

10fps in my example specifically for two reasons

  1. It was the upper range from the survey.

Why the fixation on 10fps, as if that number is set in stone? What about 15fps? 30fps? 60fps? If you really want to see higher motion speeds, record at higher fps.

And I disagree with your disagreement about the shutter freezing motion. Since you want to use 10fps, I would point out that a 1/10 shutter on a 10fps image of relatively high speed motion will yield 10 blurred images per second. A 1/1000 shutter on a 10fps image would yield 10 "still" images a second, unless the motion was exceptionally fast.

Considering that I'm not a Major League pitcher, my arm would likely be frozen during each frame when delivering the slap, though I would have to really test that premise. I can't recall if the shutter of a video camera delivers one picture per frame or several if set faster than the frame rate. On a still camera, it is one-to-one.

<edit> What would you miss in the 0.099 second gaps between images? Possibly me giving you a brief "finger"....

Why the fixation on 10fps, as if that number is set in stone? What about 15fps? 30fps? 60fps?

No fixation, it just what I used in MY question. I gave two good reasons for using 10fps to begin with 1.survey says, 2.easy to calc. And yes the closer the frame rate is to the shutter speed the less chance of missing something.

I can't recall if the shutter of a video camera delivers one picture per frame or several if set faster than the frame rate.

Now I can see where you are coming from, for yes if the camera were to 'deliver' multiple pictures per frame when the shutter speed was set to faster than the frame rate, then my position would be absurd!

Since knowingly acting absurd is unpleasant for me, you can rest assured that I don't for a moment believe this multiple picture per frame delivery scheme of yours, but I'm open to change my opinion if indeed you are right, and would then humbly offer you my other cheek to atone for insolently and superciliously even suggesting my original idea.

I guess you didn't see it. My finger is faster than .099 seconds ..!.

Wait, now I see it!

It was in all those extra pictures the camera delivered into the frame...

I guess IPVM doesn't like extended ASCII characters. I had a heck of a time getting my trick to work, LOL.

"Because at a SS of 1/1000 sec with a frame rate of 10, you are not 'watching' 99% of the time! And anything that can happen within 100ms, has a good chance of being missed."

What are things that happen within 100ms that matter in security? The answer is not much.

The solution, if the problem really exists, is not same frame rate, faster shutter, but faster frame rate, which cut down the gap between images (i.e., 10fps / 100ms intervals vs 30fps / 33 ms intervals).

The solution, if the problem really exists, is not same frame rate, faster shutter, but faster frame rate, which cut down the gap between images (i.e., 10fps / 100ms intervals vs 30fps / 33 ms intervals)

I assume you mean slower shutter. Agreed that faster frame rate reduces the 'dark' time and is the best solution as long as the increased bandwidth and storage are not a concern.

As for what happens in 100ms in security, things like bombs happen that quick. Though I'll concede that its a stretch that a blurry picture from T0.0 will be in anyway better than a clear one from T0.01. On the other hand after a few tests and practice I have found that I can swipe a casino chip of a table in under 100 ms (not at a real casino of course!). So just for fun I am going to see if I can 'beat the camera' at 10 fps. Of course Carl at 30fps has nothing to worry about.

Though, in addition to my 'supersilly-ous' question, I did ask a more 'down to earth' question that I think (assuming there is some answer) could be of use to those members looking for more practical advice, repeated here:

Are there any guidelines in surveillence for setting the frame rate optimally if the shutter speed is known or vice versa?

You hear SS should be double the frame rate in videography, but in that case they like a little blur...