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  1. #1
    Join Date
    May 2005
    Location
    Oslo, Norway
    Posts
    4

    D70 strange light concentration and horizontal lines

    I discovered this problem the first time I took night-pictures of the sky. After shooting I went back to my computer and imported the images. I noticed a strange concentration of light located in the upper left corner of all my pictures. To better be able to see it I turned up the EV compensation and found another bothering thing; in addition to the light concentration there were lots of horizontal lines stretched across the picture. I decided to do some tests and find out where the problem lied. To eliminate the lens as a problem source I removed it and put the body-cap on the camera instead. I took a couple of pictures with different shutter speeds and ISO values. What I found was that the horizontal lines were there every time, but not in the same places, they were obviously not the same lines. Somehow they were, and still are, generated by the camera, but can only be seen on very dark pictures. The upper left light concentration occurred gradually more from about 10 seconds shutter speed and upwards, independent of ISO values. This is extremely frustrating! I included my test setup below and encourage other users to test their cameras as well.

    Test setup: Remove lens. Attach body-cap to camera. Turn mode-dial to “M”. Select settings ISO 200, 30 seconds shutter. (Aperture can obviously not be set because the lens is not attached.) Take picture.

    I processed the image using Photoshop CS and Camera Raw 2.4, but I’ve also verified that I got the same result with Nikon View.

    My CR settings in PS were:
    White balance “as shot” (4800 -4)
    Exposure +4
    Shadows 0
    Brightness +150
    Contrast +25
    Saturation 0

    These settings will clearly present you with the problem if you have it.

    This is my test picture.

  2. #2
    Join Date
    Dec 2004
    Location
    Charleston, SC
    Posts
    2,364
    I have seen this happen before, but on a canon 1D ccd.
    US Navy--Hooyah!

    Nikon D700/D300|17-35 f/2.8, 24-70 f/2.8, Sigmalux, 80-200 f/2.8, 16 f/2.8 fisheye,

    Lots of flashes and Honl gear.

  3. #3
    Join Date
    Sep 2004
    Posts
    152
    Did you have NR enabled or not?

  4. #4
    Join Date
    May 2005
    Location
    Oslo, Norway
    Posts
    4
    NR disabled, I don't want the camera to do any processing at all...

  5. #5
    Join Date
    May 2005
    Posts
    3
    I've seen this a number of times and can tell you the glow at the top left hand corner is almost certainly amplifier noise. Maybe someone who knows more about the D70 sensor can confirm of deny this, but many such chips have an on-board amplifier which under certain circumstances can produce haloing exactly like your example. The giveaway cause of both this and the banding is the long exposures you are using, combined with featureless (or near-featureless) subjects like night sky shots. Read the D70 manual, it tells you this will happen!

    Night skies are much better shot with either dedicated post-processing software (various Photoshop plug-ins available, do a Google on AstoStack for a good astro-solution) or - dare I say it - film..

    With your body-cap experiment you are basically crash-testing the chip in the D70 to its extremes. It's not a particularly good camera for noise anyway; the min ISO being 200 should tell you that. However I'd like to bet the same experiment (with NR switched off!) performed on ANY digital camera will produce very similar artifacts.

    Maybe some Canon and Leica owners could post some tests and prove me wrong

  6. #6
    Join Date
    May 2005
    Posts
    3

    sorry, that should be astRostack


  7. #7
    Join Date
    May 2005
    Location
    Oslo, Norway
    Posts
    4
    Thank you for the reply, mikmac. I actualy got the answer 2 weeks ago from another forum. You're right, it is amplifier noise. This is a known problem on CCD sensors, but not on CMOS sensors (as Canon uses). However; it can be solved by turning the internal long shutter noise reduction on. I'm not planning on doing astrophotography anyway, I just wondered if it was my camera or a genereal problem.

  8. #8
    Join Date
    Jul 2004
    Location
    Monterey Bay
    Posts
    5,990
    Quote Originally Posted by agjell
    Thank you for the reply, mikmac. I actualy got the answer 2 weeks ago from another forum. You're right, it is amplifier noise. This is a known problem on CCD sensors, but not on CMOS sensors (as Canon uses). However; it can be solved by turning the internal long shutter noise reduction on. I'm not planning on doing astrophotography anyway, I just wondered if it was my camera or a genereal problem.
    Since you know this is a phenomena unique to CCD's without Noise Reduction turned on, I'm trying to decipher the point of your post. Is this something that the CCD camera owners need to be concerned about?
    D7000, D70, CP990, CP900, FE.
    50mm f/1.8, Sigma 18-125, Sigma 24-70 f/2.8, Nikon 18-105 VR, Nikon 55-200 VR, Nikon 43-86 f/3.5 AiS, Vivitar 28-90 F/2.8-3.5 Macro, Vivitar 75-205 F/3.8-4.8, SB800.
    Ha! See, I can change...


    http://d70fan.smugmug.com/

  9. #9
    Join Date
    May 2005
    Location
    Oslo, Norway
    Posts
    4
    Quote Originally Posted by George Riehm
    Since you know this is a phenomena unique to CCD's without Noise Reduction turned on, I'm trying to decipher the point of your post. Is this something that the CCD camera owners need to be concerned about?
    Not concerned, I mean it's not gonna destroy your camera. It's just that the CCD's picks up heat from the amplifier, and that it's visible on very dark images with long shutter speeds.

  10. #10
    Join Date
    Jul 2004
    Location
    Monterey Bay
    Posts
    5,990
    Quote Originally Posted by agjell
    Not concerned, I mean it's not gonna destroy your camera. It's just that the CCD's picks up heat from the amplifier, and that it's visible on very dark images with long shutter speeds.
    What I meant was concern over photo quality.

    I've worked with CCD's since 512 element single-line arrays (NEC) in the early 80's, and was just wondering what your actual point was.

    Thanks.
    D7000, D70, CP990, CP900, FE.
    50mm f/1.8, Sigma 18-125, Sigma 24-70 f/2.8, Nikon 18-105 VR, Nikon 55-200 VR, Nikon 43-86 f/3.5 AiS, Vivitar 28-90 F/2.8-3.5 Macro, Vivitar 75-205 F/3.8-4.8, SB800.
    Ha! See, I can change...


    http://d70fan.smugmug.com/

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