Results 1 to 9 of 9

Thread: Sensor dust 'move' if focal length is change ?

  1. #1

    Default Sensor dust 'move' if focal length is change ?

    Hi,

    Observe a funny situation.
    My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

    At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
    But when the focal length is at (28mm), the same spots are about 12cm from the edge.
    As you zoom in, the dusts 'move' towards the lens center.


    Is this possible ?

  2. #2

    Default Re: Sensor dust 'move' if focal length is change ?

    The sensor dust on my old Nikon sensor .. Appear at fix position.

  3. #3
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default

    Quote Originally Posted by human1969 View Post
    Hi,

    Observe a funny situation.
    My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

    At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
    But when the focal length is at (28mm), the same spots are about 12cm from the edge.
    As you zoom in, the dusts 'move' towards the lens center.

    Is this possible ?
    Possibly because of the distortion corrections that are automatically applied to the raw image. Many mirrorless system lenses rely heavily on software correction to fix optical issues.

  4. #4
    Senior Member shierwin's Avatar
    Join Date
    Dec 2008
    Location
    East Coast
    Posts
    3,334

    Default Re: Sensor dust 'move' if focal length is change ?

    A few good shots with a powerful blower should clear the dust specks off the sensor

  5. #5
    Senior Member shierwin's Avatar
    Join Date
    Dec 2008
    Location
    East Coast
    Posts
    3,334

    Default Re: Sensor dust 'move' if focal length is change ?

    Quote Originally Posted by human1969 View Post
    Hi,

    Observe a funny situation.
    My panny GM5 (with 12-32mm lens) got 6 dust spots, 3 on upper left edge, 3 on lower right edge.

    At the widest focal length (12mm), the spots are about 10cm from the edge of my PC monitor. (at 100%)
    But when the focal length is at (28mm), the same spots are about 12cm from the edge.
    As you zoom in, the dusts 'move' towards the lens center.


    Is this possible ?
    When you change the focal length, the field of view changes. The dust you see at 28mm is not the same dust speck you see at 12mm

  6. #6
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default

    Quote Originally Posted by shierwin View Post

    When you change the focal length, the field of view changes. The dust you see at 28mm is not the same dust speck you see at 12mm
    If the dust is on the sensor, it should be at the same spot regardless of focal length or lens used no?

    Unless there's some software manipulation of the pixels post-capture, which would explain the movement of the spot in the final displayed image.

  7. #7

    Default Re: Sensor dust 'move' if focal length is change ?

    i'm not expert but thats what i think.
    "Sensor dust" fixed when focussing or zooming = dust speck on sensor
    "Sensor dust" move when focussing or zooming = dust back on the glass of the lens.
    Try and use a powerful blower to blow the back of the rear glass of the lens as well.

    Have you tried using other lenses?
    Last edited by Rocky99; 4th July 2015 at 11:24 PM.

  8. #8
    Senior Member shierwin's Avatar
    Join Date
    Dec 2008
    Location
    East Coast
    Posts
    3,334

    Default Re: Sensor dust 'move' if focal length is change ?

    Quote Originally Posted by darrrrrrrrrr View Post
    If the dust is on the sensor, it should be at the same spot regardless of focal length or lens used no?

    Unless there's some software manipulation of the pixels post-capture, which would explain the movement of the spot in the final displayed image.
    My bad...

  9. #9

    Default Re: Sensor dust 'move' if focal length is change ?

    Hi,


    My understanding is that, if the dust is above 'that particular pixel',
    no matter which lens/focal length, it still on that same pixel,
    dont understand why it could 'move'.
    In-camera correct could be a possibility but that 'correction' seems a bit too much.

    I'm sure its on the sensor, cos i would see the same dust pattern (inverted) visually on the sensor with a torchlight,
    Its quite big, you can see it during LiveView as well.


    Anyway, the sensor already cleaned, just trying to understand more.
    Unfortunately i only have 1 mft lens at this moment, so cant do a swop.


    Thanks

Bookmarks

Posting Permissions

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