Heheh, now I'm getting confused. All the TV mode does is allow you to use the auto iris button, but they call it AE lock.

If you're coming from a still photography background, you probably need to quit thinking about the shutter as a means of exposure control, except in unusual circumstances. Standard shutter speeds for NTSC video are 1/48 for 24 fps and 1/60 for 30 fps. When you use a slower or faster shutter speed, you will usually get some strange things happening. Slower will cause a blur and/or strobing effect, and faster will will do other weird things, although not until you go really fast. It's common to use a slightly faster speed in bright light if you're trying to, say, shoot wide open for depth of field control and with your heaviest ND on ,you're still at an f5.6 or so. I personally use an external ND filter for that rather than changing shutter speeds. If you're shooting in low light and nothing is moving very fast (like a wedding), you can often go from 1/60 to 1/30 with no noticeable effect. But generally you want to keep at the standard speeds.

I haven't used the TV mode/AE lock in the past few weeks, so I could be wrong about this. Somebody correct me if I am. I think when you go to TV mode, you turn on the AE Lock. That does not lock it in AE mode, but locks out the AE mode, I think. Then you press the button and you are in AE mode, ie., what the world calls auto iris; release the button and you're in manual exposure. Think of it the same as the auto iris button on a full size camera with a manual lens--only they call it something else and you have to be in TV mode to use it.

Bill,

Thank you for bearing with me! I think we're saying the same thing, you're just saying it in video/film terms (something I have to learn yet).

I took out my camera and played with it in Tv mode and pushing the Exp. Lock button. Essentially, the aperture gets locked in at the settings it's at when you push the button. It's a toggle so pushing it twice will lock in the new aperture setting as per the current light level.

In Av mode it locks the shutter speed at a certain speed in order to achieve "correct" exposure.

So the way I see it, since you don't wan't to be messing with the shutter speed (other than setting it to the desired speed based on the frame rate in use), shooting in Tv mode makes things a bit easier.

One should then use Exp. Lock if the exposure might change during the shoot due to movement etc. and you don't really want the camera to compensate for these changes.

So it's like being in M mode in terms of net result.

Shiv.