Xixax Film Forum

We are shooting this week end with the JVC HD cam.  On the automatic setting, it shoots at 1/30 (which coming from the world of still photography tells me that if you shoot 1/30 of a second, there are 30 frames per second).  This setting has a problem with tracers...and you can change the shutter speed higher to 1/60 or 1/250, etc. , which is what I'd like to do.

My question is....how does this relate to frames per second in the video world.  Is the shutter speed really just a digital compensation tool...or does it really make the shutter move at 1/250th of a second.  If it's moving at 1/250th of a second...then how is it still shooting 30 frames a second?  I'm not sure I get what's going on electronically.

someone help please.

I'm pretty sure it's just an effect tool, since there is no shutter in a video camera (is there?). But the effects are similar: going lower than 1/30 will make it strobe, and going higher will give you that effect where you can capture fast motion (like the spinning blades of a fan) in detail. At least that's the way it works on my Canon XL1S.

Thanks...that's what I thought.  I just didn't want to be wrong, shoot at 1/250th of a second...then have to do some crazy conversion to make it 30 frames (or 24) per second.

no, film and video cameras do that through changing the shutter angle, not the speed, or something like that.

Interesting that it's normal speed is 1/30. Perhaps that because of the HD? The Panasonic GVX100A is set normally for 1/60 -- at 30 fps.

same with my camera

The standard dv cam(shutter angle 180) that shoots at 30fps (actually they are fields) has a standard exposure time of 1/60 . Easy way of finding the shutter speed of a standard 180 degree shutter is by dividing one by double the frame rate.  Standard shutter for 24fps would be 1/48 and so on. By standard i mean the speed that was adopted to sync sound in most natural way. But 1/30 shutter seems a bit odd for a standard hd cam meaning it is shooting your footage at 15 frames!? Can not be so, my theory is that your cam has a variable shutter speeds locked into the automatic setting? Well basically by modifying the shutter speed you produce the same effect as you would modifying frame rate so increasing the speed of the shutter to 1/250 means you are shooting at 125 frames causing the aperture to move up around 2 stops. Film exposure is a lot easier to learn than video. You never know what they stick in your good old hd cam.