I said to myself - OK, find out the IF lenses and see if if they do not blow into the mirror chamber. It looks like Nikon is confused too : quote
Internal Focusing (IF)
Imagine being able to focus a lens without it changing in size. Nikon's IF technology enables just that. All internal optical movement is limited to the interior of the non-extending lens barrel. This allows for a more compact, lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing. The IF system is featured in most NIKKOR telephoto and selected NIKKOR zoom lenses.
As an example I looked up above mentioned 24-70 f2.8G at the same Nikon site quote :
Internal Focusing (IF) system; autofocus with a built-in SWM and manual focus
But we know this lens extends and sucks/blows in the mirror chamber.
Looks like there is no lens that does not exchange air with outside, getting dust in the lens. I expected that conclusion. Is the following true?
Maybe there is no lens that does not blow/suck the air via mirror chamber?
I do appreciate all your replies!
Sorry but you are reading these marketing statements with the wrong point of view.
Internal Focus IF was back in the old days used to avoid that the big telephoto lenses balance shifted the mass forward and backward and alsos simply moving a lighter set of elements inside the barrel is much faster to move and focus. The 300mm 4.5 ED is a master class example the IF version vs the first incarnations . This turns out to be a big benefit for speedy AF as well so incorporated in most new AFS lenses.
Breathing, with regards to dust has never been a design criteria for Nikkor F-Mount lenses
Of course you can say that it is an interesting feature, reducing dust suction, and yes some lenses are definitely better or worse than others,,, Good luck hunting them down.
I prefer to choose my lenses from other criterias
