D300 - Is this a sensor glitch?

Discussion in 'Nikon' started by tom_luongo|1, Apr 26, 2008.

  1. The following image is from identical crops of 7 frames shot RAW at 2 fps. Crops are 2:1. 2 linear pixels on the image is 1 linear pixel on the original file (If I processed it right). There is a funny bright spot on the fifth frame. At first, I thought it was from a piece of lint on the sweatshirt but on closer examination it looks more like some sort of sensor glitch. All seven frames were shot at ISO 1600, 1/250 at f/8 using an SB800 in TTL mode. Camera body was set to Matrix mode metering. Active D-Lighting was turned on. Lens was a Sigma 8mm full-frame fisheye. The last exposure was noticeably brighter. I attribute that either to the aperture blades sticking or the flash deciding to give a little more output. (I forgot to do this with manual flash.) RAW files were processed with Lightroom. No noise reduction. Same LR parameters for all seven frames. I guess I'll send the NEF to Nikon technical support to see what they say. But I'm wondering what people here think of it.
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  2. For context, here's the full frame. The glitch is small, so it doesn't show up in this image, but it was in the right shoulder area of the sweatshirt.
    00PILZ-43138684.jpg
     
  3. Is this your first digital camera? This looks like noise to me, not uncommon at ISO 1600. I say noise rather than a hot pixel because it's only in one frame of a sequence. This kind of thing wouldn't even be visible unless you printed very large.
     
  4. I think it's a hot pixel. I process my RAW files from my D80 in Lightroom, and I've noticed that when I use higher ISOs I get hot pixels, but Lightroom usually automatically removes them. Sometimes it doesn't though so I end up wit a bright spot similar to the one you're looking at.
     
  5. David, D1, D70, D200x2, D300 and a couple of point and shoot models. I guess I'm inclined to go with the noise theory. Ignoring the brightness of this spot, the shape is very much like the shape of the other noise. However, at very high ISOs, noise usually shows up as an irregular pattern of spots across the entire frame. I've never seen a single bright spot like this. It's _not_ a hot pixel as Nikon software doesn't have the same removal feature of LR and I haven't seen any other frames with a feature like this. The spot does resemble a speck of dust lit by the flash in the foreground. But that's probably not it either. It will be interesting to hear what Nikon's opinion is. I'll update the thread when I hear back from them.
    00PIPq-43140584.jpg
     
  6. It may be a micro reflection. Basically, your subject moved just enough so that a stary bit of somethng reflective was in perfect alignment with the lfash and your lens. Which I wouldn't worry about because it simply won't be visible in any normal work product.
     
  7. ShunCheung

    ShunCheung Administrator

    A hot pixel should affect more than just one frame.

    Unless this pattern repeats with some frequence OR it affects a larger area, I wouldn't worry about it. I think there are bigger concerns in life.
     
  8. Glitter. Girls wear it to school. Damn stuff gets into everything. Wait'll Dan starts dating. You'll be finding glitter in your cereal.
     
  9. If it doesn't show up unless you use a microscope, and if it's something that can be fixed with one mouse click in post processing, WHO CARES what it is or what caused it. Shoot pictures and don't worry.
     
  10. A hot pixel is always in the same place because it is a phisical part of a matrix. It does not move.

    And a hot pixel would affect all the frames in the same secuence.
     
  11. While yes, a hot pixel would affect all of the frames in the same sequence, Adobe Lightroom automatically removes them, but sometimes it misses one for some reason or another. So that's why I thought it might be one.
     

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