Nikon dust pump?

[TJC]

I realize all lenses have dust and that some may evacuate air through or into the camera body. For my primes this is of little concern. But I've just entered the world of telephoto lenses and am trying to figure out if pumping dust into my D7000 is an issue. Right now i'm using a 25 year old 70-210 push/pull zoom. I'm getting great results with this old lens and have no photographic need to pop the $1400 to $2500 to replace it with an F4 or 2.8. I bought the lens new, used a few years for sports photography as my kids were growing up. It has always resided inside it's case and, without exaggeration can't be told from new.

My worry is that i don't know how this lens evaculates air as I zoom in. Even if it WAS brand new this would be of concern to me.

Anyone here know how this lens works, how well it's sealed etc?

Any help appreciated.

THX

 

[480sparky]

A bit of internal dust is of no concern. Unless you're always shooting downwind at the dirt MX track, it's much ado about nothing.

 

[Designer]

Any time a lens is off your camera, dust will get in. A pumper zoom may let more in, but probably not worth buying a different lens just for that. Assume dust will be in there needing attention from time to time. Check periodically and learn to clean your camera properly.

 

[KmH]

The air that moves when the lens is zoomed re-circulates within the lens.

The lens is not hermetically sealed (and you wouldn't want it to be) so a very small amount of air will exchanged.
Even when the lens isn't being zoomed temperature changes will cause a minuscule exchange of air.

 

[TheNevadanStig]

Any lens with a zoom has to take in air and let it out, otherwise it wouldn't be able to zoom in/out at all. I wouldn't be too concerned with it. I have a cheap Sigma 70-300 APO which I highly doubt is sealed all that well, and I have hiked probably close to 300 miles in the desert with it, snapped over 5000 shots with it, and it has about 3 tiny specks of dust inside of it. I have yet to notice ANY dust or dirt issues in the camera itself. Most zooms will take in and push out the air close to somewhere mid point on the lens, as that's where the pressures will be, between all the elements.

 

[MartinCrabtree]

I have a Nikkor 50-135 f3.5 that was sent out to be chipped. While they had it apart I asked for a CLA. They replaced a felt ring inside that had worn out and is supposed to "filter" the air entering the lens as well as dampen the slide motion. Big difference. So as long as the slide is damped I'd imaging the felt ring is still doing it's job. When I sent mine away the slide would just fall forward when the camera was pointed down. No longer the case.

 

[astroNikon]

I have a Nikkor 50-135 f3.5 that was sent out to be chipped. While they had it apart I asked for a CLA. They replaced a felt ring inside that had worn out and is supposed to "filter" the air entering the lens as well as dampen the slide motion. Big difference. So as long as the slide is damped I'd imaging the felt ring is still doing it's job. When I sent mine away the slide would just fall forward when the camera was pointed down. No longer the case.

That's interesting to know. My 75-300 slowly slides forward when pointed down. But it is all sturdy metal too.

 

[Derrel]

I think the dust-pumping zoom mythology is about right up there with the "rotate the air inside your car tires" mythology.

 

[astroNikon]

I thought the air came out of the slide mechanism , not the rear of the lens. The rear of the lens looks fairly sealed. I've been curious about this myself. I think I'll test it a bit to see where the air comes out of, but I'm pretty sure it's from underneath the outer sleeve/zoom mechanism.

 

[480sparky]

I thought the air came out of the slide mechanism , not the rear of the lens. The rear of the lens looks fairly sealed. I've been curious about this myself. I think I'll test it a bit to see where the air comes out of, but I'm pretty sure it's from underneath the outer sleeve/zoom mechanism.

Sometime, you'll feel the air blow into your eye past the eyepiece as you zoom some lenses.

 

[TJC]

Yeah, I agree there seems to be a check your headlight fluid quality to this issue. Yet, i don't buy it as myth. All lenses have dust inside them, even brand new lenses. For the lens to work dictates a change in air pressure within the lens. The questions are, where is that air going ( evacuating to)? And, is it taking any dust sucked in with it, and pushing into the camera body?

That the collective experience here is - No worries, that's the answer I'm going with.

That said, anyone who wants to jump in here, please continue.

THX

 

[KmH]

For the lens to work dictates a change in air pressure within the lens.

The air just moves from one side of the moving lens elements to the other side of the moving lens elements, and the air pressure inside the lens doesn't change because it is equalized in the lens.

 

[480sparky]

For the lens to work dictates a change in air pressure within the lens.

The air just moves from one side of the moving lens elements to the other side of the moving lens elements, and the air pressure inside the lens doesn't change because it is equalized in the lens.

Technically, the air moves because of pressure differentials created by the moving glass.