Problem with scanned negatives

Discussion in 'Film and Processing' started by stric1975, Dec 17, 2018.

  1. Hello, recently I've had some Portra 160 developed. There were 5 rolls of film and on 3 of them a problem occurred on each frame (see an example below). A thin horizontal line runs across all scans. I can't see it on the actual film. Could this be a problem with the scanner that the lab is using? No B&W films were affected. None of the films was cut, and I don't know what scanner or process they used for scanning.
    Or... is this a problem with the camera?
    Thanks 83540033.jpg
    Last edited: Dec 17, 2018
  2. It looks like the scanner had a bad day. The line is definitely artificial, likely a side effect of ICE. A rescan is in order.
    bgelfand likes this.
  3. Sandy Vongries

    Sandy Vongries Administrator Staff Member

  4. It could be a bad cell in the scanner, or dirt directly on the sensor. ThSince it appears in the same location parallel to the long edge, it is consistent with the film being scanned laterally, parallel to the short edge while the film (or scan head) is indexed along the long axis. The ghost or shading on either side of the line is probably due to image processing, such as JPEG converson. ICE produces artifacts, but more random in nature.
  5. 3 line scanners use a nominally 'blank' area of the film-holder or platen to calibrate themselves against the full brightness of the scanning lamp. The calibration is pretty much done on a pixel-by-pixel mapping basis, which compensates for any imbalance in the light across the frame, scanner lens vignetting, and high or low output photosites.

    As a consequence, a speck or two of dust in the calibration area can result in just such a stripe as is shown.

    It could also be caused by dust on the tri-linear sensor, but less likely that simply dust on the glass platen.

    Rescans are in order, after someone cleans the scanner.

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