See the Canon EF 100 400 L IS pump action

Recently I have built a FAQ for the Canon EF 100 400 L IS and in one of the answers I brought up the subject that the push/pull zoom of the Canon EF 100 400 L IS sucks the dust right into the sensor.
I got some emails from owners confirming that they have had no dust problem with that lens whatsoever which, by the way, was a big relief for me since I am expecting mine to arrive any day now.
Recently a fellow photographer did some scientific tests with his Canon EF 100 400 L and here are the results

Olli sealed with double rubber a plastic bag on his lens to check the amount of air going in and out at every pump

notice the volume difference of the bag.

The original thread can be found at Photography-on-the-net forum

  • Well, the air has to come from SOME place. Also as long as you put it on the body at 100mm it will only suck from the body, and blow THAT air in there again… If you put it openly without any lenscovers to 400 and then put it on the body: that’s rather stupid.

    Have fun with the lens!

    • @Steven, Thanks Steven for this tip I’ll keep it in mind