Turning all of your DSLR settings like exposure, white balance, and focus to manual will eliminate most flicker.
If you are still having problems, you’ve probably got a case of “aperture flicker”.
Shooting wide open eliminates the closing down of your aperture and in theory should eliminate aperture flicker, but not always. Plus shooting wide open can result in soft edges even with the best lenses.
This is why the lens twist method tutorial by Dustin Farrell can be extremely useful.
The lens twist method
Lens Twist Method Written tutorial
While holding down the depth of field preview button (DOF Preview) press the lens release button.
The aperture blades will be closed down to your selected aperture.
Now while holding down both buttons twist the lens as if you were removing it. The twist should be a very small turn. You should now see a “00″ where your aperture information used to be.
A great way to test the amount of twist is to put your camera in its live view mode before twisting. As soon as the camera has lost contact with the lens you will hear the mirror return to stills mode. This is a good thing because the camera is no longer talking to the lens and cannot create aperture flicker.
Now that you have executed the lens twist you must perform a quick test. Every camera body and lens combination requires its own perfect twist. To test to see if you have twisted just enough simply take a picture. If you have done this correctly, besides the “00″ aperture reading, the camera will act normal. If you haven’t you will get an error message like the one in.
Re-attach the lens and try again. Some lens and camera body combinations are difficult to get just right. Take a few pictures to make sure you do not get an error.
The only negative to the lens twist method is that the camera will not be able to record the lens information to each picture taken. However, as long as you remember what lens you used for the time lapse, most software will allow you to manually enter a photo’s lens information. Nearly every shot in Landscapes: Volume Two was done with a twisted lens.