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Dust & zoom lenses.

Discussion in 'Digital Image Editing & Printing' started by MikeS, May 6, 2006.

  1. MikeS

    MikeS Active Member

    There have been many discussions about dust on sensors. It seems to be generally accepted that dust is not a problem with cameras fitted with non-interchangeable lenses. I have seen comments suggesting that a wide-ranging zoom such as the Nikon 18-200 VR will reduce the need to change lenses and hence reduce the risk of contamination.

    However, it occurs to me that the act of zooming out must cause air to be drawn into the camera body. Surely this will equally apply to all types of cameras. Do current digital only lenses have any type of air filter to ensure dust does not enter the camera? If so, do older 35mm lenses have the same feature? I was looking at my Nikon 28-105 recently and was surprised to see the amount of dust on the inner surface of the front element.
    Catriona likes this.
  2. Sharp Shooter

    Sharp Shooter Well-Known Member

    Hello Mike

    Interesting post. You're right in what you say. Some lenses are well sealed to protect against dust, but they are in the more expensive range only as far as I know. But I could be wrong.

    Although there is less risk of contaminating the sensor, one of the worst lenses I have for dust is the Canon EF 50mm 1.8. It’s worthwhile shining a bright torch through our lenses’ elements to see what has accumulated on internal elements. Can be surprising! And disappointing…

    Wide-ranging zooms are not well known for their image quality or useful aperture range so may not be the way to go in combating dust whether they are sealed or not.

    Dust on the internal elements (and mould too) are a more serious concern because having them cleaned is a lot more painful than cleaning the sensor once in a while.
  3. fatsamurai

    fatsamurai Well-Known Member

    Hmm. I was wondering about this. My Sigma zoom has a little spot of dust on the inside of the front element. It isn't appearing on images so it doesn't bother me, although I do worry about how it got there.

    Considering that the lens was only about £100 - is it worth having it professionaly cleaned? Is it something that can be done at home?

    I'm not worried about it for now anyway.. just wondered.
  4. Benchista

    Benchista Which Tyler

    Don't worry about it. A LOT of dust will lose contrast in the lens and increase flare, but any lesser amount won't have any impact.
  5. Iloca

    Iloca Well-Known Member

    I was surprised to see dust in my 1 year old approx Nikkor 18-70 lens, much worse than a older Zuiko 35-70 zoom. I'm not too concerned TBH, I'm more concerned by the amount of dust on the sensor, for a while it was just one spot, then another but recently it's really bad, enough to make me think about cleaning it.

    I wonder if the increased use of plastic in lenses (and bodies for that matter) makes them more likely to attract dust.

  6. Benchista

    Benchista Which Tyler

    Surely if plastic was attracting dust (which is not an unreasonable hypothesis), it would also keep the dust away form the lens surfaces? Just a thought...
  7. Iloca

    Iloca Well-Known Member

    Ah, good point. :cool:

  8. MikeS

    MikeS Active Member

    Thanks for all your comments.

    I discovered others discussing the same issue on DPReview.com :

    I would have assumed that the joints between the lens barrels would be sealed with velvet or similar material much in the same manner as the film slit in a 35mm certridge. It seems perhaps not. It would be interesting to receive a comment from some of the lens makers.

    Nick, your theory of static seems entirely reasonable. Maybe we should carry an anti-static cloth in addition to a lens cloth .
  9. LenShepherd

    LenShepherd Well-Known Member

    The question was about dust on sensors, rather than dust in lenses, though the 2 can be related. Obviously rapidly zooming in or out with a lens that extends a lot disturbs more air and shooting in dusty conditions means there is more dust about.
    If you go on a Nikon training cause they advise keeping rear lens caps and rear elements clean because that is how a lot of dust gets in. They also advise switching the camera off so the sensor is not charged and pointing the camera down whilst changing lenses.
    New sensors seem to hold less charge than old ones so dust is less off a problem than it was and cameras like the D200 (which currently outsells Canon's 3 top models combined) has a simple dust removal procedure described on page 186 of the instruction book.
  10. Dorset_Mike

    Dorset_Mike Grumpy Old Fart

    Having just taken a damaged Minolta 35-70 AF zoom apart to rob it of its chip, it looks as though the front and rear groups of elements are individually well sealed, the space between the groups however would appear to be open to the atmosphere, especially from the rear end.
    When fitted to the camera or fitted with caps then probably not so bad but still nowhere near a seal. A knife blade could easily be inserted in places.
    No sign of any velvet, nor rubber seals where you might expect to find them.
    Cheers MIKE
  11. casey

    casey New Member

    Just a couple of observations:

    I guess that the action of opening and closing the lense aperture will eventually free some material from the leaves which will form dust in the lense.

    But back to the sensor, I recently spent a few days in the northern Sahara desert where the sand is as fine as talc.

    Instead of using prime lenses I took a 18-200 which, with the exception of the loss of the odd wildlife opportunity, gave me everything I wanted without the risk of that fine abrasive getting in my camera.
  12. kevin burns

    kevin burns New Member

    Ok our cameras have a shutter that sits right in front of our sensor. When looking through the viewfinder the shutter is closed, so when zooming in and out the sensor is protected by the shutter. Also our cameras have airflow direction as well that tries to keep the moving air away from the sensor and tries to divert the air to the sides and downward to force particles around the sides and downward from the center of the black box that the sensor sits in. This is done to keep dust and such off the mechanical moving parts. Yes dust does get onto our sensors but not that much from the zooming action of the lens but rather from that soft black mirror slap pad, the tiny hairs do come loose and end up on the shutter blades and work their way onto the sensor.

    1) vacuum out the camera's body, simply put the mirror up in clean mode, and vacuum out. The vacuum hose will not have an attachment and usually will be of the same size of the lens mount. The trick is to NOT let the vacuum hose touch the camera's lens mount and this allows fresh air into/and onto the exposed sensor to create a draft to help remove the dust as the vacuum is sucking.
    2) For the the dust that is adhered to the sensor more tightly than a more hands on cleaning will be needed.
    Under no circumstance never blow anything into the camera as that will only blow more dust onto the sensor.

    As far as dust on the inside of the lens barrel and optics, there is a few to clean them.
    1) A vacuum placed at the rear of the lens will suck out the dust from the lens.
    2) A air compressor with a water trap. Use compressed "clean water free" air from a compressor and blow the stuck on the glass dust free and vacuum out. Simply blow the compressed clean water free air into the rear of the lens while the lens is at full zoom.
    Never use aerosol type blowers as the aerosol/ propellant will spot the glass.

    This is an old post I know this but people do read this stuff. Figured put the correct info up.
    EightBitTony likes this.

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