Why is the 100-400 concidered a dust sucker?

I've had no dust inside the lens (that I can see) in the 6 months I've owned mine (and it's had lots of use).

As for increased sensor dust as a consequence of the "pumping"? I wouldn't know. I just regularly rocket blow it out when the dust becomes visible.

RikWriter wrote in post #3068940
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.

STRANGE!
I guess everyone is different,Had my lens for over 2 years and shoot with it 2-3 times per week. Never had DUST issues. I will say that I have 3 bodies and do not need to change my lenes in the field.(most of the time)

Just because the 100-400mm is a push/pull design vs. a twist doesn't make it any more - or any less susceptible to dust, either into the lens or the camera body.

The 100-400mm is not a weathersealed lens whereas the 70-200mm (IS) for example, is. So this may have played a small part in what people are seeing.

It could also be a bad "seal" on the lens (it's not weathersealed, but it still has gaskets).

I'm not saying it can't happen. I'm just saying this lens is no different than any other just beacuse of its design (weathersealing aside).

the.digital.guy wrote in post #3069130
STRANGE!
I guess everyone is different,Had my lens for over 2 years and shoot with it 2-3 times per week. Never had DUST issues. I will say that I have 3 bodies and do not need to change my lenes in the field.(most of the time)

Changing the lens didn't seem to be the variable. The worst part was, I couldn't even blow the dust off in Yellowstone or Alaska because it was somewhat moist...it pretty much just stuck to the sensor.

Here are a couple of examples from the Yellowstone trip:

HTTP response: NOT FOUND | MIME changed to 'image/gif'

HTTP response: NOT FOUND | MIME changed to 'image/gif'

looks like a dirty sensor to me:

[Image]
Make = Canon
Model = Canon EOS 5D
Orientation = top/left
Software = Adobe Photoshop CS Windows
Date Time = 2007-04-19 12:54:31

[Camera]
Exposure Time = 1/250"
F Number = F22
Exposure Program = Aperture priority
ISO Speed Ratings = 200
Exif Version = Version 2.21
Date Time Original = 2006-06-06 20:03:43
Date Time Digitized = 2006-06-06 20:03:43
Shutter Speed Value = 8 TV
Aperture Value = 9 AV
Exposure Bias Value = -0.67EV
Flash = Flash did not fire, compulsory flash mode
Focal Length = 70mm
User Comment =
Flashpix Version = Version 1.0
Color Space = Uncalibrated
Exif Image Width = 800
Exif Image Height = 533
Custom Rendered = Normal process
Exposure Mode = Auto exposure
White Balance = Auto white balance
Scene Capture Type = Normal
Gamma = 2.2

[Thumbnail]
Thumbnail = 160 x 107


with an aperture of f/22...that's definately dirty sensor

I don't think there was ever any question as to whether or not the sensor was dirty... More a question of if the lens caused that.

I always wondered where all that air would go when pushing and pulling that lens. Never thought about having a dust problem. Definitely something to consider down the road. Thats is some heavy dust in those pictures. Wow!

When I first bought my 100-400, I hated that lens for the dust issues. I had more problems with dust and it on my 5D than any combo I'd ever owned...and said so on POTN several times...

HOWEVER, over time, I realized a few things....the 5D is the dustiest camera I've ever owned, it just seems to gather dust and I've learned to live with it's foibles...(but not knowing about that didn't help the 100-400's review any)...

After several serious cleanings/rocket blowings of the 5D, I noticed a few things...the first being that I could use the 100-400 as much as I ever did with no noticeable dust accumulation.

The 100-400 DOES move the air a lot more in the camera chamber...Ollie did a test on here somewhere where it shows just how it can inflate/deflate a plastic bag, and the other types of zooms cannot do this...

So, my re-vamped opinion of the 100-400 is that while it does move the dust already in the camera, I don't think it necc. sucks in any dust into itself or the camera.

(btw, I'm still not a big fan of the lens, but am trying to give an honest evaluation of it's pluses and minuses...)

My understanding is that the lens doesn't acutally suck in dust but that it pushes the dust around inside your camera. Obviously that's not good either but if you make sure you keep the inside of your camera relatively dust free it shouldn't be a problem I suppose.

EDIT: Hadn't seen the post above me before posting but his write up is what I've come to understand about the lens.

Having had this lens for about 15 months now I haven't had any difference in dust issues as in the the previous year before I had it...and this with the same camera. I could easily imagine it slightly displacing dust which is already present in the camera, but sucking more in? I don't think so...not that I have experienced...

Just throwing this out there... Why don't we hear anyone complain about dust with the 28-300mm or 35-350mm lenses? Same design. Sure, there's a LOT more users of the 100-400mm lens out there, it's obviously a much more popular lens - but still...

RikWriter wrote in post #3068944
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...

The difference is other people are saying it happens no more and no less significantly than any other zoom design - not that it never happens.

Permagrin wrote in post #3069392
...
The 100-400 DOES move the air a lot more in the camera chamber...Ollie did a test on here somewhere where it shows just how it can inflate/deflate a plastic bag, and the other types of zooms cannot do this...

Hmm... This is an interesting experiment and I believe I'll try it on my 70-300 when I get home from work. It would be easy to rubber band a sandwich bag onto the back of the tele-photo fully extended and then zoom in causing the barrel to retract. If there is an air path from the lens chamber to the back of the lens, the bag will inflate.

Seems that people who own the 5D have the most problems..........coul​d it be the camera attracts more dust for some reason?