Aperture flicker and other artefacts

Found that when using the 24 to 105 f/4L IS lens, there seems to be quite a lot a movement between the stills in a timelapse sequence and also, there is quite a lot of "aperture" flicker between shots too. Aperture flicker occurs because the aperture blades of a lens return each time a shot is taken and apparently, the camera cannot precisely close the blades by exactly the same amount each time the shutter is released.

Firstly, another lens - the Tokina 11 to 16 f/2.8 was tried and this produced zero movement between shots (which is interesting in itself) and also, the "twist" method to keep the aperture blades on the camera constant was used on the 24 to 105 as well, which is a neat trick:

Aperture fix via "twist" method demonstrated here: https://vimeo.com/30974031

A couple of very shorts tests were carried out with the camera set to take a shot every 2 seconds over a period of approx. 1 minute. The clips below are therefore extremely short, however, they hopefully aid this discussion. 

1. Using the Canon 24 to 105 f/4L IS lens, the lens was stopped down to f/8 to close the blades down a little and using the trick mentioned in the video above, the blades were forced to stay in this position. Interestingly, flicker was noticeably reduced, however there was still some slight movement between some of the shots as this very short clip demonstrates.

It might not be noticeable in the video above, but there is some slight movement between some of the shots. There definitely therefore appears to be an issue with lens when used for timelapse sequences.

2. Using the Canon 50mm f/1.8II lens with its aperture blades forced down to f/8, the same short sequence was shot and again, the results were much better, with no noticeable movements between successive shots: