@Mt Spokane
It should not flicker due to the aperture in manual or AV. If the lighting changes, and you have a fixed aperture, you are forcing it to flicker.
The aperture does stop down in live view, but it will vary with available light.
Hi, for standard video this is almost correct (although even 'constant' aperture lenses twitch a little when zoomed, at max aperture or stopped down) for timelapse it is false in practise, no matter how right it sounds is theory.
The issue is that -like most SLRs with non-stop down metering- the EOS cameras leave the aperture diaphragm (or to use the video term, iris) wide open until the point of exposure. This is to assist composition and focusing.
When the image is taken the iris momentarily stops down then releases. Great for stills. For timelapse this can be a pain because:
-the iris has to stop down exactly the same each time or you end up with flicker.
and
- if you shoot say 10s of timelapse, thats 250 or 300 stop downs, a lot of wear on the iris diaphragm blades, that can easily be avoided
It should not flicker due to the aperture in manual or AV. If the lighting changes, and you have a fixed aperture, you are forcing it to flicker.
Timelapses are most effective at dawn or dusk, when the light changes dramatically over a very short period of time. If you set your camera up properly with enough exposures (I find 0.8s @ 2s intervals works best -avoids the NR and stops the sensor getting too hot) you get nice even exposure ramping. Full manual is the only satisfactory way to control the camera for this.
The aperture does stop down in live view, but it will vary with available light.
Live view also has exposure compensation, which cannot be disabled on some cameras, so what you see on the back on the camera isn't always what will be on the card, particularly with uncoupled lenses, manual lenses and where exposure times are longer.
Here's an example of the flicker. I'd done everything right except uncouple the lens. This was consistent manual expsoure settings, and although you'll see the desired exposure ramping, you will also observe the slight aperture flicker as the lens doesn't stop down exactly the same each time.
http://www.flickr.com/photos/scott1shpau1/5658874949/#secret953212111b