a novice question re shutter speed
 

I plan to shoot my next film in 30p. My question is shutter speed. I did a little research on a few boards and I was surprised that I couldn't get a clear answer. My thought was when i shoot in 30p I should choose a shutter speed of 1/30. It happens to also be the speed the camera likes. However, I read in some cases 1/60 is the correct or the desired speed to use and in other cases it's 1/30. I know in the end the choice is mine in regard to what I'm planning to shoot, but I was just wondering if there was a standard shutter speed like when you shoot in 24p, 1/48 is the standard shutter. I would appreciate any feedback. Thank you.

standard shutter speed for 30p, if I'm not mistaken, is 1/30.

From my experience, there really is no concrete answer to your question other than the fact that 1/30 is the standard for 30p, just like 1/60 is the standard for 60i.

Adjust the shutter as needed by the lighting conditions or for style purposes, but generally, it's just for proper exposure.

Let someone more experienced chime for more info though.

Scott,

I agree with Roger saying there is no concrete answer- no right or wrong, necessarily.

I think maybe you couldn't get a clear answer cus most shooters probably don't have strong feelings about the difference between 1/30 and 1/60. I've asked questions before where the only response was crickets.

If you do a quick shooting test at both 1/30 and 1/60 you might see the difference; but go higher than 1/60 and it'll become even more clear what the effect of increasing the shutter speed is.

I vote 1/60. You're still shooting 30fps, it's just progressive instead of interlaced. 60i (30fps interlaced) shutter speed should be 1/60, so in my opinion, so should 30p.

In my experience, shooting 30p with a 1/30 shutter makes your footage look interlaced (even though we know it isn't). Don't ask me why, that's just the way it is.

Don't you lose resolution with the slow shutter speeds? On the XL1s, anything below 1/60 (1/30, 1/15, 1/8) caused a loss in resolution. I don't know if it's the same with the XL2.

I shot a 30p project to match another camera, I shot a test and found that for what we were doing 1/30 was too slow and caused way too much motion blur.

So what I suggest is shoot a test at 1/30 if you are happy with it go with it.
If not then find the shutter speed that best matches the situation you are shooting.

Bill

That's true too. I didn't even think of it. So, again, I say 1/60 is the "correct" shutter speed for 30p footage, just as 1/48 is for 24p footage.

thank you for all the informative feedback. I'm going to do some test shots this weekend. Just as long as it doesn't look too "video like."

1/60th will look much more "video" than 1/30 which will look more "film" like. As Ash always seems to point out, the shutter speed is a "Motion Effect" control, not an exposure control! So you need to set the shutter for the look you want. Slower gives you more motion blur, which is more like film. Faster makes the image look more "chopped"...

I have to disagree with you, Brendon. I don't think there's anything about 1/60 that's particularly video-like, or that 1/30 is any more particularly filmlike. You can adjust shutter angle on a film camera just like you can adjust shutter speed on a video camera. That said, the "standard" on a film camera is 48hz, which gives two exposures per frame. 1/60 at 30p will give you the same.

As you point out, it's simply a matter of the kind of motion rendering you're after. In my experience, there's too much motion blur at 1/30 for most applications. If there's anything moving at all in the shot, it will just be a big blurred blob. If that's what you want, then OK.

As for this idea that shutter speed is only an effect and not an exposure control, I have to take issue with that as well. Shutter does have an effect on exposure. It does also produce a visual effect. But keep in mind that any means of adjusting exposure will have a "side effect." Aperture affects depth of field, gain affects grain, ND filters can affect color, and shutter speed affects motion rendering. Setting exposure is always a compromise between these thinngs. You're making choices about which of these effects you want, and in most cases, which ones you can live with. Any means of adjusting exposure will affect the image in some other, unrelated way.

Disagreement is fine, it's all about taste in the end. My understanding was that film was filmed at 24 frames/sec and not double exposed, but was projected at at 48 frames/sec, with each frame being shown twice.

From your list of exposure control, I feel the best is ND filters. Not sure why you think they affect color? Not changing color is obviously what they are designed to do, and I have not noticed any shift.

That said, if an image is going to be too bright, you have to get it under control. The "best" option is ND and what you do after that depends on the look you are going for and what you can most afford to compromise. With the small sensor sizes, depth-of-field is often too big already, so stopping down may be OK. If overdone, aperture will cost sharpness - which may be a bigger problem than DOF.

I suppose the real answer is to shoot test footage of the subject you want to shoot and view it on the intended display. Then you will know what you like. Kind of like experience making one better!

Yes, but I agreed that motion rendering is a matter of taste.

OK, I think what I said was a little misleading. The standard film shutter is 180 degrees, which means that light is striking the film plane exactly half of the time. At 24fps, the film is thus exposed for 1/48th of a second. With this shutter angle, there's a 2:1 ratio between exposure time and frame rate. If you speed up the frame rate on a film camera, the shutter speed will increase in equal proportion because of the 180-degree angle of the shutter. Since 180 degrees is the most widely-used shutter angle in film cinematography, the motion blur at 1/60 per sec. @ 30p will approximate the motion blur of most footage shot on film.

Projecting at 48 fps with each frame projected twice will have no effect on motion blur, because the motion blur is recorded directly to each frame of film.

In a perfect world, ND filters would affect all wavelengths of light equally. In actual practice, even good ND filters affect some wavelengths more than others.

The only point I was trying to make was that 1/60 @ 30p is a better candidate for approximating film on video than 1/30 would be, because of the motion blur characteristics of a shutter speed that is twice the speed of the frame rate. That's how film is shot at least 90% of the time. If you want the super-duper motion blur of 1/30, then go for it, by all means. But 1/60 will appear more "film-like" to most people. If film-like is what you're going for, then you'll probably want to go with 1/60.

The bit about ND filters was only meant to illustrate that there is no 100% "pure" way to adjust exposure. Each means of exposure control can affect the picture in unrelated ways.

If your goal is to create a "film-like" effect by using 30p, then I find that 1/30 of a second actually does create a bit less of a film effect than does 1/60. At 1/30, the motion blur is seamless from one frame to the next, creating a more fluid type of motion like you see in regular video footage. In fact, shooting 60i at 1/30 creates the same effect because both fields of the 60i contain the same information since 1/30 will cover both fields.

Edit: Oops, I see that this has already been explained to some extent. That's what I get for not reading the whole thread. Durr!

Most of the film look comes from production values and progressive scan. 30P should be shot at 1/60th, any lower and you are adding in some motion blur and almost looking like 24P at 1/48th shutter. I find 30P best for action, sports, music...fast paced stuff. One HUGE caveat...30P does not transfer to PAL well, cannot be incorporated in a 24P timeline easily and for that reason, does not bump to film well.


ash =o)