shutter speed for 24p, 30p 50 and 60

[Jason McDonald]

What are the optimal shutter speeds for these video settings for those that have captured video with their 7D so far? Are there certain speeds to avoid when using a specific mode?

[Jim Jolliffe]

I haven't received my 7D yet, so this is purely speculative, but I would have guessed it is best to imagine you are using a film camera with a 180º shutter (it took me about 5 minutes to find that degree symbol on my computer). Therefore at 24p use as near to 1/48sec, 25p use 1/50sec, 30p = 1/60sec, etc. I'm not sure if these speeds are possible on the 7D but try and stick as near to them as poss.

If you shoot with faster shutter speeds than this, the image will become crisper but can become jittery and strobey. Some people like this effect and it can work on fast moving objects. Sometimes looks good on flowing water etc, but I think it can look a little contrived.

The problem arises when shooting outside. If you want a narrow DOF, you shoot wide open (say f1.4), then you want as slow ISO as possible, eg. 100, so then when you also want to shoot at 1/50sec you need bundles and bundles of NDs, probably about 6 stops worth in full sun.

It will be interesting to here what other people think about shooting above 1/50sec and whether it looks okay or not. Again, my answer is purely speculative and based around what I would do on a video or film camera. Also, what is the 7D like at shooting below 1/50sec? could be handy in low light to get that extra stop.

Jim

[Jonathan Morrow]

Originally Posted by Jim Jolliffe

...it is best to imagine you are using a film camera with a 180º shutter (it took me about 5 minutes to find that degree symbol on my computer)

<ALT> 248

very, very handy if you are a surveyor...

[Jim Jolliffe]

alt 0(zero) on a mac.ºººº

[Jeff Reagan]

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!

[Chris Medico]

Hi Jeff,

You are quite correct about shutter speeds to reduce motion blur in still photography but its a different world when you start shooting moving pictures. Motion blur is a tool to better show motion and direct attention. If you keep every frame of the video sharp it can look very jarring to the viewer. You don't have to look any further than the beach scene of "saving private ryan" to see how using a high shutter speed can create a look that isn't appropriate for lots of subjects.

The best thing to do is use a relatively slow shutter and learn to carefully control camera motion. This will allow you to use the blur to bring the audience to your intended focal point of the image. The overall look of the video will be more pleasing to the viewer.

[Jeff Reagan]

Thanks for the information, Chris... I'm debating between shooting 24p or 30p tonight at an indoor concert.

If I shoot at 30p I will use 1/60th second shutter speed. If I shoot at 24p I will use either 1/50th or 1/60th for the shutter speed. Would flourescent lighting come into play if I shoot at 1/50th at 24p? Thanks!

[Barry Green]

Yes, absolutely it could. If it's a magnetic-ballast fluorescent (or street lights, or HMI, or any of those types of light sources) then using 1/50 can cause rolling bands in your footage. In cases like that you simply *must* use 1/60.

There's an easy way to test to see if you're shooting in a situation that would be susceptible to the interference -- just pop over to a high shutter speed for a few seconds. Crank that shutter up to 1/500. If you see massive thick orange bands on the screen, then you know you *have* to shoot 1/60. If the screen still looks clear of orange bands, then 1/50 is okay.

[Jim Jolliffe]

With a film camera, if you are in the U.S. (60Hz), shooting either 24fps or 30fps (and 60fps too), you can shoot at any shutter angle and avoid lamp flicker.

See:
Cinematography Electronics,Inc.- Flickerfree HMI Speeds

I guess it would be the same rule with HD, shooting 24p or 30p and any shutter speed.

Anybody know if this is correct??

[Barry Green]

It is very much NOT correct for rolling-shutter video cameras!

The rolling-shutter CMOS cameras' interference with ballasted light sources has nothing to do with frame rate. It's all about the shutter speed. There are certain shutter speeds that are HMI-safe, but no frame rate is HMI-safe.

1/48 is NOT safe, it will cause rolling/scrolling bands in your images.

Safe shutter speeds are 1/60, 1/40, 1/30. It doesn't matter what your frame rate is, if your shutter speed is not one of the above (or perhaps 1/120) you're going to have interference and complications and scrolling bands when shooting under magnetic-ballast fluorescents or HMIs or sodium-vapor or mercury-vapor lamps.

[Jim Jolliffe]

So I guess in the U.K. where it is 50Hz, safe speeds are 1/50 and 1/100?

Can the 7D do 1/50 or 1/100?

[Chris Medico]

Just double checked and yes, 1/50 and 1/100 are available.