A vexing issue

Discussion in 'Open Discussion' started by TonyTurley, May 1, 2013.

  1. TonyTurley

    TonyTurley TalkEmount Hall of Famer

    Apr 24, 2013
    West Virginia, USA
    I have a rather vexing issue I'm trying to solve. Every now and then, when photographing something with a light background, a spot appears near the top center of the image. Sometimes it is more faint than others, and other times, it is not there at all. Through a series of tests, I have determined it is lens specific. I've attached 3 images of a sheet of paper. First image is from a Vivitar 50/1.8. Note the spot at the top, plus a random pattern of lighter spots, which I've never seen in "normal" images. Next is from a Vivitar 28/2.8 Close Focus. The random pattern of spots is still there, and the spot at the top is darker. Third image is from a Vivitar 24/2.8 Auto WA. No spots! So what gives? I have cleaned the sensor several times using the in-camera procedure, and I am loathe to attempt any manual cleaning procedure. Besides, if it is the sensor, how could the same pattern of spots appear with some lenses and not others? I'm puzzled.

    Tony
     

    Attached Files:

  2. davect01

    davect01 Super Moderator

    Aug 20, 2011
    Fountain Hills, AZ
    Dave
    If it is sensor dust, it usually only shows up on the extreme aperture side.
     
  3. WoodWorks

    WoodWorks Super Moderator

    Dec 12, 2012
    Ashland, OR, USA
    David
    What Dave said. If it is sensor dust (and given that it appears with different lenses, that's a good bet), it will only be visible with higher apertures, i.e. ~f/11 and up.

    Don't be afraid of cleaning your sensor. I've cleaned the sensors of at least 5 different cameras now using the LensPen sensor cleaner (NOT their lens cleaner!!!). It's easy, and with a little care, perfectly safe.
     
  4. TonyTurley

    TonyTurley TalkEmount Hall of Famer

    Apr 24, 2013
    West Virginia, USA
    Thanks for the replies. It is sensor dust. I repeated the above test, and the spots appeared and reappeared based on the f-stop setting. It just so happens that in the above images, the 3rd was on f/8, while the others were stopped all the way down.

    Tony
     
  5. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    Yep - Best way to check the sensor is to stop all the way down, shoot at a blank wall or cloudless sky, and be out of focus. Them little buggers show nice and obviously then.

    I had a couple of dozen spots on my 5n sensor, and just could not get rid of them. Finally took it in to local camera shop and had them do a wet cleaning. The girl was very thorough, and went through at least half a dozen Sensor Swabs before she gave up. I think I'm down to two very light marks - One top left and one lower right in the sensor. But all the main bug-me's are now gone.

    Now to research Sensor Swabs and such to do it myself next time. Cost me $40, and as I said, she went through at least $20 in swabs. But I understand the process now and wouldn't be afraid of doing it.
     
  6. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    The NEX series bodies are among the easiest to clean the sensor for because of the large diameter lens mount and the short registration distance. The flipside of that is the sensor is closer to environmental dust. Everything is a tradeoff. :)
     
  7. Jazzer

    Jazzer TalkEmount Veteran

    344
    Nov 6, 2012
    New York
    Larry
    Probably my biggest complaint about the NEX system coming from a P&S. The sensor is a dust magnet and unlike a DSLR that has a mirror the sensor is out in the open every time you change a lens. On the other hand, as you say, it should make it easier to clean... if I wasn't such a chicken. :biggrin: I know the time to face it is going to come and sometimes I think I should buy an inexpensive used earlier NEX camera so I can experiment on that now instead of on my new 6. :)
     
  8. davect01

    davect01 Super Moderator

    Aug 20, 2011
    Fountain Hills, AZ
    Dave
    Agreed, dust is a big issue. Just be careful.
     
  9. lenshoarder

    lenshoarder TalkEmount Veteran

    297
    Feb 7, 2012
  10. TonyTurley

    TonyTurley TalkEmount Hall of Famer

    Apr 24, 2013
    West Virginia, USA
    Thanks for the tips. I'll have to order something, because all of the camera shops around here have closed.

    Tony
     
  11. Jaf-Photo

    Jaf-Photo TalkEmount Veteran

    484
    Mar 25, 2013
    I think that dust is fairly mild. I would just try to blow it off with a rubber blower. If it doesn't show at normal apertures, leave it there. Wet cleaning should be a last resort in my opinion. Knowing how hard it is to get a lens surface really clean, a sensor is even trickier.