Dust particles inside lens

On giving my Pentax D FA 150 - 450 zoom it's external clean, I noticed that there are a few dust particles inside the 86mm glass lens, not been aware of them before.
I've always believed that the unit is sealed so am baffled as to how they've got there.
Anybody else had the same issue? if so, what's the solution please?

I have had my 150-450mm since day one of release and to be honest I have never bothered to look and see if there is any dust present (same with my 15-30mm/24-70mm/70-200mm) as it's not going to make any difference to the output and it would also cause me to continually worry about it.

I'm pretty sure you will always get some dust in a large zoom lens , by it's very nature it can't be 100% sealed as it has to move air through itself when moving back and forward.

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Except that it is supposed to be dust and weather resistant. Having said that I normally wipe the extended lens barrel if I have been photographing waves or in the rain, with a microfibre cloth I keep in the bag.

Resistant being the important word, not dust and weather proof.

I used to have a Canon 100-400 f/5.6 which was weather sealed, it's nickname on canon forums is the dust pump.

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Virtually any zoom lens, when zoomed, experiences a change the internal volume capacity. If the lens was completely sealed you would not be able to zoom it at all. Modern weather resistant lenses do most of their breathing through the lens mount....ie air is pushed and sucked out of the mirror box. You cannot avoid dust in a lens, and thankfully minor amounts do not affect the picture quality.

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Peter



My Flickr page

That was my first thought, but if the camera body is similarly sealed then I don’t see how that would work.

I guess that's one reason DSLRs are not waterproof, just water and maybe dust "resistant".

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Best regards, John

I've always regarded anything claiming to be weather or dust resistant (or proof) as meaning that you can take it out in bad weather or dusty conditions and it's unlikely (but not impossible) to come to any harm. However, if I do anything that affects the protective barriers, all bets are off. A bit like a raincoat. Keep it on and done up and it keeps the rain out, fiddle with buttons or zip and water might get in.

As for dust inside cameras, it's reasonable to assume that there will always be dust within the body of a SLR because none of us changes lenses in a totally dust-free atmosphere. There's a sensor dust removal mechanism for very good reason. And the dust that's shaken off the sensor is still inside the body.

Steve

I used to watch a professional photographer go to town with a Rocket blower, taking an eternity blowing inside the mirror box at 4 x 90 degrees and then 4 x 45 degrees and then blasting the body cap that was quickly applied. He then did the same with the lens he had just removed, as well as its caps before putting them back on. Then he would do the same in reverse - blast the replacement lens (put the rear cap back on) remove the body cover and blast inside again, then quickly mount the replacement lens. He commented once that there was no way he was allowing any dust to get in at all - but agreed that his task was ultimately impossible.

One day I noticed that I had lots of dust bunnies on my images and I recalled my professional friend's behaviour. Guess what I do now, without fail, every time I change a lens?

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Both the *istDS and the K5 are incurably addicted to old glass

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Thank you all for your comments, how naive of me to not realise that most things with moving parts will probably allow small particles to ingress. I do clean the camera body inside and out in the correct way but seeing dust particles inside the lens glass alarmed me at the time, I'm less worried now.