The Shutter Speed Heresy

[Norm Kaiser]

I wanted to discuss the "best" shutter speed to use in general situations. I'm going to talk a lot about the "ideal" shutter speed to use for indoor sports, but the more I got to thinking about the subject, the more and more curious/confused I became.

So here's the deal: As a general rule of thumb, what is the best shutter speed to use for indoor sports (volleyball, boxing, basketball, etc.)? I understand that the lighting of the building plays a critical role, but is there a good rule of thumb to follow and if yes, why?

Let me throw some of my own thoughts out first. Please be aware that I come from a still photography background, so I'm probably stuck in a few paradigms. But to me, it seems logical that a videographer shooting indoor sports (or any indoor action...say a well lit fight scene for movie) should always attempt to use the FASTEST shutter possible. That is, considering the available light. So, for example, say you're shooting an MMA fight. Let's also say that the ring is very well lit with truss lighting. In such a case, if the videographer can get, say, the camera to cooperate at 1/500 (i.e., the exposure is correct), he should shoot it at that fast a speed.

HOWEVER, I've heard and read many videographers throw out different rules of thumb. Let's explore some of those. I've had guys tell me that you should never shoot above 1/60, that the shutter should simply be twice that of the frame rate. So if you're shooting 30fps, the "correct" shutter would be 1/60.

Why is this "twice the frame rate" rule still relevant? Is it? Or does that only apply to flim movie cameras with a rotating shutter?

But then I've read that many videographers who shoot big events -- say outdoor NFL games -- shoot them at much faster shutter speeds.

My particular camera's owner's guide says you should shoot indoor sports at 1/100. Again, any ideas why it says that? Is it because they just assume that the camcorder is going to be used by the Average Joe who just wants to point it at the action and get "acceptable" results and 1/100 is a good catchall for most indoor venues?

If you can shed any light on the subject or have ideas to throw out, please do!

[Bruce Watson]

Originally Posted by Norm Kaiser

Why is this "twice the frame rate" rule still relevant?

Because the human visual system still responds to it.

You're falling into the trap that many still photographers fall into. That is, thinking that motion pictures are just a series of stills. But no one views a motion picture as isolated stills. Instead, they view all those stills as a single motion picture. What makes it work, that is, what gives you the illusion of seeing something actually move, is the blur in the motion captured in the individual frames. This lets one frame lead into the next and results in the appearance of smooth motion. And it turns out that the amount of blur you need to make a convincing illusion comes from using a shutter speed that's around twice the frame rate.

If you run the shutter speed way up, what you get is stuttery -- like strobes in a nightclub. The individual frames are clear, but the effect of the motion is lost. And for some material, this is an effect that you might want. But not normally.

But talk is cheap, and this is way easy to test on your own. There's zero reason to take my word for it. So do a little work, run some tests, and make your own decision based on what you see. But if in the end you decided that you get your best results with a shutter speed that's twice the frame rate....well, you won't be the first that's seen it.

[Brian Drysdale]

Also, if you have no shutter in place when shooting progressive, the effect is quite ghostly.

Select the shutter speed for the effect you want. "Saving Private Ryan" used a faster shutter speed for the stutter. sharper edged effect on explosions. Some people use it on aircraft propellers, although if you're flying in one where you saw the blades in real life you should be worried.

For general work more or less around one over the twice the frame rate works best. For interlace video I only use the shutter for effect, normally I just leave it switched off, however, you do need to use a shutter for progressive frame.

I suspect the higher shutter speeds used in sports is to improve the slow motion.

[Norm Kaiser]

Gotcha.

So do you think the "double the frame rate" rule applies to outdoor sports, too? It seems like it would, right? Oddly, though, my camera's user manual says use a really fast shutter speed for outdoor sports in bright sunlight.

So confused.

[Norm Kaiser]

Originally Posted by Brian Drysdale

I suspect the higher shutter speeds used in sports is to improve the slow motion.

Ahhhhhhhhhhhh...ding ding ding! That's the sound of the lightbulb turning on over Norm's head.

[Jon Fairhurst]

Here are the rules I follow:

Under lights use 1/30, 1/60, or 1/120 in 60 Hz countries and 1/25, 1/50, or 1/100 in 50 Hz countries - period. Otherwise you get rolling bands, which are virtually never an attractive effect.

For a "normal" look, go with something close to 1//48 when shooting 24 fps. That's often 1/50 and is generally 1/60 under 60 Hz lights.

In the situation that there is little light, the camera is on a tripod, and there is limited subject motion, one can use 1/25 or 1/30. It's not used for effect. It's used to get more light and less noise. I can't recall ever doing this in real shooting situations but it's a trick I hold in my back pocket. Okay, one might do this stylistically along with frame blending for a smeared, altered state of mind look.

When you want to show urgent, frenetic action, go for faster shutter speeds. 1/250 or faster is very crisp. Under lights, 1/100 or 1/120 might be as fast as you want to go. This is an artistic choice.

Note that the above is for shooting at 24 fps. Shooting 60 fps for live TV or shooting at higher frame rates for slow motion playback may have different/additional rules.

[Heiko Saele]

For sports, it is not even double the frame rate, but exactly the frame rate. Look at how HD sports channels record their football and basketball - they use 1080i, that means 60 or 50 frames per second, with a 60 or 50 Hz shutter (50/60 depending on if they are in Europe or the US)

If you record 1080p 50, that doesn't matter, you'd still use 1/50, because that will give you fluid motion. As soon as the shutter speed is shorter than the frame rate, there is some motion missing in between frames, and the movmement becomes stuttering.
This slight stutter is what looks filmic about 24 fps with a 48Hz shutter, and it is what makes for an unnverving effect in action scenes when 24 fps and higher shutter speeds like 1/200 are used (I think they used this in Saving Private Ryan as an example)

The only way to get realistic, fluid motion, is to use a shutter speed that is exactly the same as your frame rate.
Of course the frame rate has to be at least 48 to do that, if you film 24fps with a 1/24s shutter, that will look really blurry

[Heiko Saele]

Originally Posted by Brian Drysdale

I suspect the higher shutter speeds used in sports is to improve the slow motion.

But only for the slo-mo cameras! The slo-mo camera still uses a shutter speed corresponding to its frame rate - it records 500fps, so it can use a 1/500 shutter

[Dale Guthormsen]

Everything already posted is dead on. I shoot out door high speed sports and have shot a lot of hockey and bball as well. If you are going to work a bit in slo motion you can up the shutter speed slightly. I shoot at 60 or 90, on occassion 120. for movement that resembles what we actually perceive I prefer 1/60.

sometimes it is more important to be at a particular aperature however and that may change things.

[Garrett Low]

Norman, to answer your question about people saying to shoot twice the frame rate it is because this is a throw back from when film cameras measured the time of exposure using a degree of the shutter. Old cameras use to have circular shutters. 180 degrees would mean that the shutter was open for half of the time it took to go around. Or, the time the exposure would occur would be half of the frame rate. By setting the shutter angle this way it gave a good mix of detail but had enough motion blur to be comfortable to watch. This is more of a convention born out of what we are use to seeing when watching movies in a theater.

Now a days, however, this is not strictly observed. The shutter speed you choose should match the effect you wish to present. Most sporting events use higher shutter speeds because they want a "crisper" look. Less motion blur. Since you come from a stills background you know higher shutter speeds are needed to freeze the motion. So sports shooters tend to push the shutter speed as high as they can. But there is a point at which the shutter speed is too high for the frame rate and you get unwanted effect. Primarily in the form of strobing. This happens when each frame has too much black time. Since motion pictures has a time element think of it as flashing a picture for set amount of time. If a new picture appears every second, and you let each picture be shown for half a second, you then would see black for half a second, then the next picture comes up. Speed this up so that you see a new picture every 1/30th of a second and show the picture for 1/60th and black for 1/60th. That's how the video is captured. So when you have too much black time and not enough exposure time, you get a strobing effect. I find that for a 30fps video, this occurs when exposure times get shorter than 1/100th. So if you have enough light, you can shoot higher than even 1/60th.

So the ideal frame rate is difficult to say. For documenting sports or capturing it for broadcast, I like to use the highest shutter speed I can before strobing occurs and for which the lighting allows. The point that Jon Fairhurst brings up is very important. You need to know the frequency of your electrical source for lighting or you will get some very nasty looking video, especially when shooting high frame rates for slow motion.

BTW, 60i is not a frame rate of 60 frames per second. It is 60 half frames per second which are pulled together to create one complete frame every 1/30th of a second, or 30 frames per second (in broadcast land it's actually 29.97fps). So, if you are shooting 60i, 1/60th is still 180 degrees or double the frame rate.

[Casey Danielson]

Originally Posted by Bruce Watson

Because the human visual system still responds to it...

...what gives you the illusion of seeing something actually move, is the blur in the motion captured in the individual frames. This lets one frame lead into the next and results in the appearance of smooth motion. And it turns out that the amount of blur you need to make a convincing illusion comes from using a shutter speed that's around twice the frame rate.

Well said, Bruce! I love this way of looking at it. Controlling and manipulating blur is such a fine art, man. Developing instincts for what different frame rates and shutter speeds *feel* like when combined with a variety of objects moving at and different speeds through chosen depths of field -- there's the rub! It took me a long time just to start getting a sense for this, and I'll be the first to admit I'm still working on it.