Helpful Posts Helpful Posts:  0
Results 1 to 9 of 9

Thread: More than dust: anyone know what this is? End of sensor?

  1. #1
    DanK's Avatar
    Join Date
    Dec 2011
    Location
    New England
    Posts
    3,940
    Real Name
    Dan

    More than dust: anyone know what this is? End of sensor?

    Noticed a few dust bunnies when I edited a shot taken with my 50D, so I did a test shot (uniform surface, f/32). It showed numerous dust bunnies, along with the big blob that you can see toward the right. A cleaning (air, then a brush, then wet cleaning) removed some dust bunnies, although a few remain in the image below (e.g., toward the top left). Cleaning had no effect whatever on the blob, which looks like nothing I have ever seen before. Examining the sensor (well, the AA cover, anyway) with a loupe showed nothing.

    Anyone know what this is? I have a bad feeling about this, and it happened only two days before a trip to the mountains.

    thanks for any ideas.

    More than dust: anyone know what this is? End of sensor?

  2. #2

    Join Date
    Dec 2008
    Location
    New Zealand
    Posts
    17,662
    Real Name
    Have a guess :)
    Are you sure it's not on the rear element of the lens?

  3. #3
    DanK's Avatar
    Join Date
    Dec 2011
    Location
    New England
    Posts
    3,940
    Real Name
    Dan

    Re: More than dust: anyone know what this is? End of sensor?

    Colin,

    Thanks. Problem solved. The rear element looks fine, but I just tried several other lenses, including a second copy of the one in question, and no blob, so something else is wrong with the lens. it has a month left on warranty, so in it goes.

    Dan

  4. #4

    Join Date
    Dec 2008
    Location
    New Zealand
    Posts
    17,662
    Real Name
    Have a guess :)

    Re: More than dust: anyone know what this is? End of sensor?

    No worries Dan.

    Just shine some light through it - you should be able to see the obstruction.

  5. #5

    Join Date
    Aug 2010
    Location
    Stockholm, Sweden (and sometimes Santiago de Cuba)
    Posts
    1,089
    Real Name
    Urban Domeij

    Re: More than dust: anyone know what this is? End of sensor?

    The obstruction could as well be at the front element of the lens. At f/32 on a 100 mm lens, dust on the sensor should be much sharper. This spot might be on the front or rear element of the lens or on the filter if there is one.

  6. #6
    gcowan's Avatar
    Join Date
    Jan 2011
    Location
    Sydney Australia
    Posts
    269
    Real Name
    Graham
    It looks like oil or a drop of some other fluid on the sensor. It is a job for a pro.
    I speak from bitter experience.
    Graham

  7. #7
    DanK's Avatar
    Join Date
    Dec 2011
    Location
    New England
    Posts
    3,940
    Real Name
    Dan

    Re: More than dust: anyone know what this is? End of sensor?

    Quote Originally Posted by gcowan View Post
    It looks like oil or a drop of some other fluid on the sensor. It is a job for a pro.
    I speak from bitter experience.
    Graham
    That was my first thought, but it can't be, because it only happens with this lens--not even with a second copy of the same lens, which I happened to have on hand.

    The blob is there with and without a filter.

  8. #8
    gcowan's Avatar
    Join Date
    Jan 2011
    Location
    Sydney Australia
    Posts
    269
    Real Name
    Graham

    Re: More than dust: anyone know what this is? End of sensor?

    Dan,

    Hmmm... Looking at it on a monitor rather than a phone it is a little too out of focus.

    Can't really help any further except that the repairer that fixed my 5D had really good optical gear to find the dirt etc. and special cleaning gear. I used a static charged brush, which ended up spreading the muck all over the sensor. It didn't really occur to me that there might have been too much lubricant in the works. If it had been dust, then the brush would have worked.

    It might be something similar in the lens, and if it is clear fluid it might need UV light to show it up. There are lots of possibilities. I have had mould growing in a lens before; but in my memory it just gave a general and really bad softness.

    Graham

  9. #9
    DanK's Avatar
    Join Date
    Dec 2011
    Location
    New England
    Posts
    3,940
    Real Name
    Dan

    Re: More than dust: anyone know what this is? End of sensor?

    Graham,

    The lens is now all packed and double boxed, so I can't look further, but my guess is that it is something on the forward surface of the rear element or on one of the other elements near the back. The puzzle is that this is an L prime, so it is well sealed, and I have really babied it during the 11 months I have owned it, so I have no idea how muck could have gotten into it. Given that is under warranty, I'll let Canon disassemble it and figure it out. It costs me only one-way shipping.

    Dan

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •