We've got another new writer (as we promised a few weeks ago) – Dustin Farrell is going to be contributing to planet5D about what he's learned doing timelapses (remember the “Landscapes Volume 2” post?) If not, you should go watch that to see how amazing Dustin is! We're thrilled to have him contributing to planet5D!
Dustin on the Twist
On almost a daily basis I get an email asking for help on how to shoot better time lapse. The most common question that I get is how to get rid of flicker. Turning all of your DSLR settings like exposure, white balance, and focus to manual will eliminate most flicker. If you are shooting time lapse in all manual modes and still having problems, you've probably got a case of “aperture flicker”. This type of flicker is caused by a DSLR's inability to open and close the aperture blades of a lens the exact same amount every time.
There is a lot of literature online that suggests shooting wide open to eliminate this problem. Shooting wide open eliminates the closing down of your aperture and in theory should eliminate aperture flicker. In most cases it does. However, you now have created two possible problems. First, since you are now shooting wide open, there is a chance that you have increased your shutter speed tremendously to be able to expose correctly. Believe it or not, very fast shutter speeds can also cause flicker. By eliminating one DSLR inaccuracy you have created another. It is hard for a DSLR to open and close a fast shutter at the exact same speed every time. If this problem sounds familiar to you, use some neutral density filters and/or a lower ISO so that you can slow down your shutter speeds.
The next problem created by shooting wide open is that it usually doesn't result in the best picture quality. Even the best lenses become soft on the edges when you are shooting wide open. Often the “sweet spot” of a lens is found two to four stops from wide open. I try to never shoot with the aperture all the way open with wide lenses and this is why I prefer the lens twist method.
How to lens twist: While holding down the depth of field preview button (DOF Preview) press the lens release button (picture 1).
The aperture blades will be closed down to your selected aperture (picture 2).
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 (picture 3).
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 (picture 4).
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 2” was done with a twisted lens.
Dustin's demo video[tentblogger-vimeo 30974031]
(cover photo credit: snap from the video)