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Noise patterns/dodgy sensor?

Discussion in 'Panasonic Cameras' started by Alex Haigh, Apr 24, 2012.

  1. Alex Haigh

    Alex Haigh Mu-43 Rookie

    Nov 26, 2011
    Dorking, UK
    Hello :43: people. I'm afraid I am going to have to prevail upon your helpfulness and wisdom again.

    I have a GF2, shooting RAW + low quality jpg, and was recently looking through some of my pictures and noticed a few of them are showing quite marked patterns or stripes of noise of some kind, even at low ISO. The first one I noticed it in is this one shot with a Helios 44 at ISO100, 1/3200sec (can't remember what aperture but I think it was somewhere between f/5-6):

    DMC-GF2    ---    0mm    f/1.0    1/3200s    ISO 100

    Looks fine at 1000x750 reduction but this is the 100% crop:

    DMC-GF2    ---    0mm    f/1.0    1/3200s    ISO 100

    There is are fairly pronounced dots in the dark areas which are arranged in suspiciously neat rows. From the RAW file (downloadable here: http://dl.dropbox.com/u/60910319/Sample photos/P1020435.RW2 ) the effect is less severe but still definitely there.

    I had a look through some more shots and found similar and often more severe cases. This is the worst example (shot with Panny 14mm ISO800, 1/5sec, f/2.5, RAW file available here: http://dl.dropbox.com/u/60910319/Sample photos/P1020481.RW2 ).

    DMC-GF2    ---    14mm    f/2.5    1/5s    ISO 800

    This is the original image from the camera, not cropped, just resized to 1000x750 pixels and as you can see there are clear stripes across the shaded area.

    There are many more examples with stripes of varying intensity at various different angles. I'm assuming that since it's happening regardless of which lens I'm using it must be a problem with the sensor and because of the regularity of and the fact that it changes/isn't always there it is something other than dirt on the sensor or hot/dead pixels.

    Any ideas what might be causing this, or what I can do about it?

    All input gratefully received.

  2. ripleys baby

    ripleys baby Part time philistine

    Aug 10, 2011
    suspiciously neat rows ?

    Vertical ? horizontal ? diagonal ? I ask because i cant see anything wrong with this image. (horizon is a little bit off though)

    Downloaded onto my nice imac, opened in aperture, edited,

    Cant see a thing. Nice picture though.:smile:
    • Like Like x 1
  3. Alex Haigh

    Alex Haigh Mu-43 Rookie

    Nov 26, 2011
    Dorking, UK
    Interesting... I can definitely see a series of dots, most pronounced on the coat sleeve in the crop. To be fair it is fairly subtle and I just noticed that if I look at my screen from a different angle they almost disappear, but I'm sure there is something.

    Can you see the lines across the shadow area in the second photo?

    Thanks. You're right about the horizon though. I was distracted timing it so she obscured the post and sign that were in the background. Here is a version after a bit of tinkering...

    DMC-GF2    ---       f/1.0    1/3200s    ISO 100
  4. Aegon

    Aegon Mu-43 Veteran

    Nov 3, 2011
    Portland, OR
    I don't know for sure, but maybe this is related to the RAW converted you are using.

    What do you use to open your files? If you open the files in other programs instead, do the artifacts still exist?
    • Like Like x 1
  5. lubov

    lubov Mu-43 Veteran

    Apr 4, 2011
    Ive just opened it up in RPP and yes they are there, something is not right.
    • Like Like x 1
  6. Brian S

    Brian S Mu-43 Top Veteran

    Apr 11, 2009
    Most sensors these days are "Native ISO 200" or so. Shooting at ISO 100 is a "Pull" from their optimal setting. What do you get when shooting at ISO 200?
    • Like Like x 1
  7. lubov

    lubov Mu-43 Veteran

    Apr 4, 2011
    I have a GF1, same sensor and have shot many frames at 100iso.
    This is something odd. I can see fairly reguarly spaced light pixels in her jacket
    that have nothing to do with the camera settings.
    • Like Like x 1
  8. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    You know, at first I too didn't notice anything. Then you mentioned the sleeve and I can see them now.
    • Like Like x 1
  9. Alex Haigh

    Alex Haigh Mu-43 Rookie

    Nov 26, 2011
    Dorking, UK
    Thanks everyone for your thoughts. The consensus seems to be that there is indeed something wrong so I am at least reassured of my sanity, but a bit concerned about the state of my camera (I wonder which is more important...)

    I do have a slightly convoluted route from .RW2 to processed image (via Adobe DNG converter and Adobe Camera Raw) but I don't think that's the cause. The images in my original post are from SOOC jpegs which show the same artefacts as my RAW files, suggesting (to me at least) that the problem is with the sensor/in camera.

    It's still under warranty so guess I'll see about sending it back for repair/replacement. Just wanted to check I wasn't missing something obvious or expecting too much from it. Thanks again for all your input.
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