Does the Canon 24-70L/2.8 extract when zooming and hence let dust come into the lens?

[henrik_jacobsen]

I don't have the 24-70 L lens but do consider to buy one.

 

I have seen a picture of one of these and it looks to me that the lens is

becoming larger in some pictures indicating it will allow air and hence dust to

be sucked into the lens. Is this correct?

 

Thanks for your help.

 

/Henrik

[leopoldstotch]

Its specified as dust/weather resistant. Besides, lens dust doesn't really affect the image anyway.

[tridakfoto]

Like already stated the dust wont affect your images.

 

BUT it does extend and with the hood on the lens DOES NOT extend outside the hood, its all covered by the hood. Seeing as its an "L" lens I wouldn't worry about any of that anyhow. (weather proofing ....)

[mendel_leisk]

The 24-70 does extend/retract. Maybe check out:

 

http://www.the-digital-picture.com/Reviews/Canon-EF-24-70mm-f-2.8-L-USM-Lens-Review.aspx

 

Lot's of lens info there: comparison views of retracted/extended, size compared to similar lens, with/without hoods, etcetera. The author of that site does mention the need to use a UV filter (or similar) with some lens to complete the sealing, but not with the 24-70.

 

Whether or not that travel draws air into the spaces between the lens is debatable. There is a gasket at the inner edge of the back flange of the 24-70. If it's to be effective (for weather sealing, with weather sealed bodies), there shouldn't be air travelling within the cavities between lens elements.

 

Interesting: 24-70's travel is opposite to most, it's longest at the wide end.

[PuppyDigs]

All lenses--even weather resistant ones--must vent air in order for the elements to move

during zoom and focus operations. Otherwise those little motors would need a lot more

torque. Nested barrels have a skirt to reduce dust and moisture intake. However, dust will

always eventually find a home in your new lens. In fact, it is likely to ship with factory

installed dust, driving the anal retentive insane. When you buy your next new lens, shine a

penlight in the barrel and peer in the other side. Yes, you'll see dust. Maybe even a few

bubbles in the glass...

[jcolwell]

The lens gets longer as it zooms to wider angles. I've been using one daily for about 18 months and there's no dust to speak of in it.

[colinsouthern]

"I have seen a picture of one of these and it looks to me that the lens is becoming larger in some pictures indicating it will allow air and hence dust to be sucked into the lens."

 

You might think so in theory, but in practice it just doesn't happen - this lens has a venerable reputation for quality.

[alan_myers]

I agree with the other responses....

 

First, yes the lens extends significantly when zoomed to the wide end.

 

Second, you don't have to worry about it sucking in dust. Like all L-Series lenses, it's at least reasonably well sealed to help prevent that (but must have some sort of venting to allow air pressure to equalize inside and out, as noted).

 

I've been using my 24-70 for a little over a year, sometimes under some very dusty conditions. Dusty enough that my cameras and lenses get vacuumed when I get home from the day's shoot.

 

I have not had any problems with excessive dust getting inside the lens. A few more years using it like this, I may need to send it in for service and a cleaning. But, I consider that to just be par for the course, occasional servicing is to be expected if we are to use our camera equipment.

[henrik_jacobsen]

Thanks for your help. I will have a look at this lens in January when I expect some after-christmas-rebate.

/Henrik

[mark from thailand]

Same as James; I've been using mine for around 2 years now & no problems with dust.

Sensor dust & misbehaving sensor pixels are another story though!