Medium Format Negative with Test Pattern to Adjust Scanner Focus?

Discussion in 'Digital Darkroom' started by robert_digrazia, Jun 14, 2018.

  1. Using Epson V600 with BetterScanning variable-height negative holder, medium format

    To adjust the height of my negative holder, I wish to use a monochrome negative (black and transparent) with a test pattern that has sharp edges.

    Does anyone know where I can find such a negative?
     
  2. When I adjusted mine, I used a strip of Tri-X that had been developed in Rodinal and had well defined high contrast lines in the image.

    The grain is course enough that the V700(and presumably also the V600) can easily resolve it, and I used Rodinal because it gives well defined edges to the grain(solvent developers like D76 and HC110 soften the edges of the grain). The high contrast lines were used to confirm focus, but I mostly used the grain as a guide.

    When I print in the darkroom, I use a device called a "grain focuser" to focus the negative. This is basically a microscope that looks at a tiny portion of the image, and the enlarger is focused until the grain is visible through the microscope. It works with even fairly fine grain film, but focusing on the grain in a scanner is a good way to get things as sharp as possible.
     
  3. Do you have a connection to established printing industry (small offset shop or silkscreening)? If so, I'd recommend getting some old lithographic film from their trash and cutting it down.
     
  4. Just use a piece of fogged and developed film and scratch a cross in the emulsion with a needle.

    Unless you're trying to measure the resolution, that'll be as good as anything else. Or as Ben suggested, use a grainy neg and use the grain to focus.
     
  5. At $32, a bit pricey, but it looks like what I need.
    Can I cut strips from this sheet to fit a medium-format film holder for the Epson V600?
     
  6. No need to cut it, it is for medium format, it is of the same dimension of a 6x6 medium format picture.
     
  7. I bought one.
    It's 75 X 90 mm, (3 X 3.5 in). Time to apply scissors!

    On hasselbladrepair.com, there is a Focus Calibration Sheet described as 22.9 X 16.2 cm for 28 euros.
     
  8. Mine is 6x6, it came with the scanner.
     

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