Why is the 100-400 concidered a dust sucker?

There have been several threads in which the 100-400 is referred to as a dust sucker and I just read the comment once again in another thread. Since the 100-400 is my next big purchase, it is something of a concern. But how specifically does the push/pull mechanism of the 100-400 suck in any more air than a twist mechanism? Both have extending barrels which will cause the pressure inside the lens to decrease due to the expanding volume thus causing outside air to rush in. If there is dust in the outside air, it will too enter the lens. So the only difference between a push/pull zoom and a twist zoom is that the action used to extend the barrel is changed, not the result of that motion. In both cases air is going to be sucked into the lens. What am I missing? Is this just one of those photo urban legends that if repeated enough becomes the popular truth? Or is there really some design flaw that somehow causes more dust to be sucked in?

Many feel that the Push/Pull feature of the lens will suck dust into the lens.
I have owned mine for 2 years now and shoot sports and motor sports.
NEVER had a problem with dust.

Anyone else paranoid that you will extend the lens to its maximum too hard one day and it'll come flying off the end?

The 100-400 is a nice, versatile lens, so don't be scared off of buying it. But yes, it does indeed pump more dust into the sensor than a twist-zoom lens.
Why? Try an experiment. Get a 50-500 Sigma and a 100-400 next to each other, both mounted on cameras. Pick up the Bigma and twist the zoom out to full extension, then back. Takes a while, don't it? Now pick up the Canon and zoom it out, then in as fast as you can. Zoooooom/Whoooosh.
It sucks in more dust because you can (and probably will) extend and collapse it faster.
Now take the 100-400 off the camera and hold the end up to your face. Put your hand around the edge of the extending section so that just the rear of the lens that mounts on the camera is exposed, and collapse it. You'll feel a breeze on your face.
It is not a legend or a myth, it's a fact.

Like anything else if you take a good care of the item there would be less or no problems. So far no dust problem with mine.

One of the reasons that made me choose the Sigma 80-400 over the Canon 100-400 was the push-pull zoom action that is very widely said to be (1) odd, and (2) suck dust.

Honestly, I "used" these two rumours, along with a $400 price difference, to justify my selection of the Sigma over the Canon L.

After using the 80-400, a lens that has an equally large barrel that extends very significantly during zooming, I can say that partly, the zoom action is delayed by the amount of air that travels in and out of the lens. When turning the zoom ring as fast as I can, I can actually hear the sound of the air as it travels through the small vents that have to be built into the lens design, just to allow zoom.

I come to the conclusion that the only lenses that don't actually suck/blow air are the ones that employ inner focus and inner zoom (i.e. expensive L grade lenses that don't extend during zoom/focus and can be made weather sealed).

I have been using one for over 3 years in Europe the US and all across India, in some of the dustiest, sandiest and inhospitable condition imaginable and have never had a problem. I change lenses frequently and with little caution and I clean my sensor when it needs it. Having your photography behaviors limited by this fear nonsense is like only driving your car when it is not raining because you do not want to get it wet.

the.digital.guy wrote in post #3068802
Many feel that the Push/Pull feature of the lens will suck dust into the lens....

I guess that’s what I am asking, is this just a perception or is there some truth to it. I just can't envision the mechanism that would cause more dust to be sucked in as opposed to a twist design.

Anke wrote in post #3068817
Anyone else paranoid that you will extend the lens to its maximum too hard one day and it'll come flying off the end?

I have had other push/pull zooms and have shot with the 100/400 and like the mechanism. It seems natural that as the lens extends your lens support hand moves along with it. It always felt as if the lens stayed more balanced and didn’t get front heavy. So, no, I never really had the feeling that it was going to zoom off. Maybe if I wasn’t looking through the lens and actually saw the barrel just zooming into space it might change my perspective.

Two words: "urban legend."

neil_r wrote in post #3068840
.... I change lenses frequently and with little caution and I clean my sensor when it needs it. Having your photography behaviors limited by this fear nonsense is like only driving your car when it is not raining because you do not want to get it wet.

I have no phobia about lens changes, nor sensor cleaning, and do both often. I have also pretty much made my mind up and am just waiting for the spring rebates to kick in though the 10/22 keeps calling as well. My question is more out of curiosity as the dust sucker moniker seems to have become an attribute that the 100-400 will never shake. I have had friends warn me against the lens lest I zoom once and instantly fill the camera chamber with dust dunes rivaling those of the deepest Sahara. I’m just wondering where it’s reputation is coming from.

Double Negative wrote in post #3068899
Two words: "urban legend."

No, in fact, it's not. It may not have happened to you, but it HAS happened to some people. It may be, for that matter, sample-specific, but I've had two different 100-400s now and it has happened with both.

Double Negative wrote in post #3068899
Two words: "urban legend."

That's what i am thinking.

Double Negative wrote in post #3068899
Two words: "urban legend."

RikWriter wrote in post #3068915
No, in fact, it's not. It may not have happened to you, but it HAS happened to some people. It may be, for that matter, sample-specific, but I've had two different 100-400s now and it has happened with both.

Strap on the hard hats and prepare for yet another pantomime season of "Oh yes it is!" - "Oh no it isn't!"

gjl711 wrote in post #3068917
That's what i am thinking.

Then you're thinking wrong. I bought my 5D in October of 2005. That month, I went to Utah and Arizona, to Arches, Zion and the Grand Canyon. With me I took my 17-40, 24-70, 70-200 and 400 prime. I changed lenses quite a bit and hiked the backcountry extensively especially in Arches. I had very little dust on my sensor at trip's end.
The next year, I went to Yellowstone with my family, then Alaska by myself. I took the same 17-40 and 24-70, but instead of the 70-200 and the 400 I took the 100-400. I had my sensor cleaned professionally just before both trips. On both trips, I used the 100-400 extensively, and on both trips by the second day, I had so much dust on my sensor that I had to spend almost a half hour cloning out dust spots on every landscape shot I took.

neil_r wrote in post #3068939
Strap on the hard hats and prepare for yet another pantomime season of "Oh yes it is!" - "Oh no it isn't!"

Well, I do find it a bit annoying when people say that it can't happen, since it's happened to me on a regular basis. It doesn't make the 100-400 a bad lens---hell, I still own one. But you do have to take it into account and be prepared for it.