Scanning with digital camera: photomerge problems

Discussion in 'Scanning and Scanners' started by Photopathe, Jul 29, 2018.

  1. Photopathe

    Photopathe Member

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    Hi!
    I scan my films, mostly medium format, with my Fuji X-pro 2 digital camera (24mpx) and a Fuji XF-80mm macro lens with results that are quite satisfying to me. When I scan medium format I usually do it in two shots, which gives me a final image size of about 32 mpx. There is one issue I have and it's with merging the shots. No matter if I use LR or PS and no matter the projection method, the edges of the frame are almost never completely straight. I find it suprising as it's not a panorama so there is no difference in perspective between shots, they are all on the same plane (and the shots are sharp from edge to edge...). It's especially annoying when I want to keep the black edges of the film as it then shows this flaw even more. I'm under the impression that it has to do with lens distortion even tough this lens is supposed to have very little. Still I notice it and correct it so lines seem straight on each separate shoot but when merged a curve or a bend still appears in the final merged image. Side note: I am using a mac.
    Any advice would be greatly appreciated!
    Thanks!
     
  2. shutterfinger

    shutterfinger Subscriber

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    I use dedicated for 35mm and flatbed for larger. I have a D300 and 60mm f2.8 Nikkor Macro. I run Windows 10 and PSCS 5.1. Have you used Lens correction under the Filters tab to correct the curvature?
    Its also possible not to have the sensor parallel to the film. I would photograph a sheet of graph paper with fine markings in the setup for film copying and evaluate the result in PS or LR or both.
    Small drafting layout tools can also be used as targets for error checking.
    Film flatness is another possible cause.
    0.01 mm curvature may show up in the image but not the camera eyepiece.
     
  3. jeffreyg

    jeffreyg Subscriber

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    I don't think the problem is with the computer. I'm not quite sure why you merge two identical images but you mention that you make corrections before merging. Perhaps the editing of each image has something to do with it although you say the subject matter remains sharp. I use my trusty old Epson 4780 scanner and SilverFast Studio 8 software that can be set to make multiple scans but it does one after another without any manipulation on my part. Despite what many will claim about flatbeds and the factory film holders the scans (120 and 4x5 films) are very sharp even with enlargements to 16x16 and 16x20 with cropping. I don't include the black edges when scanning or printing.

    http://www.jeffreyglasser.com/
     
  4. JerseyDoug

    JerseyDoug Member
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    I had the same problem. Did you try the Reposition projection method in PS? It’s the only one that worked for me.

    (The problem is that the panorama/stitching tools assume the camera is located in one spot and is pointed in different directions for the different shots. Merging partial scans is exactly the opposite. The direction is the same for every shot, I.e., parallel, while the location changes, relative to the negative. The software is understandably confused, resulting in the curved edges. The reposition option is there for exactly what you are trying to do.)
     
  5. danitoma

    danitoma Member

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    HI,

    while I don't know what your problem is (the times I tried this with lightroom worked perfectly), maybe you could try using Microsoft Image Composite Editor. Off course this adds another step to the process, but I found it worked very well and it's free
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator
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    Make sure the sensor, lens, and work to be copied (neg or transparency in this case) are all in alignment. Use a copy stand, if you can (tripod if you don’t have a copy stand), and either a laser leveling tool or a spirit level. I use an Omega spirit level designed for aligning enlargers, which can be calibrated to one plane, so that you can adjust the other planes to align with the first one.

    How much overlap do you have between frames? When I want to do a hi-res scan, I may shoot 6 or 9 frames, and there should be at least 20% overlap between frames to get good alignment. I use Photomerge in PS5.

    Some people make jigs to move the copy work in perfect alignment with the camera or vice versa, but I’ve found this to be unnecessary. Photomerge has no problem aligning panels that have been rotated, as long as they are all in the same plane.

    Sometimes it may turn out that the whole stitched image is crooked, but then just straighten it out using the crop and rotate tool. That can cause a slight loss in resolution, because you’re cropping out the misaligned portion of the frame, but this is minor, and if you really need it, that’s the time to consider making a jig that lets you keep the work perfectly straight with respect to the sensor or just shoot more frames per image to get a higher resolution.
     
  7. OP
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    Photopathe

    Photopathe Member

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    SRGB3203.jpg SRGB3204.jpg
    Sorry for the late reply. I use a Durst enlarger as a copy stand. Everything seems to be well aligned (attached pictures). I do a good amount of overlaping (around 25%). I did try reposition as well as the other projection methods. I dont edit photos before merging but at some point I tried lens correction in LR (not PS) to see if it would help but it didn't.
     
  8. michr

    michr Member
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    Reposition should work. If you're running a newish version of Photoshop, load the files into layers, highlight the layers and use edit->auto-align layers option and see where that gets you. Also, I've had quite a bit of luck using the camera RAW transform tools to square up the subjects of my panoramas, as if I'm looking at them head on. When I photomerge these images, Photoshop doesn't create a curved projection. So you might try squaring up using the edges of the frame. Another thing to note, since your subject is two-dimensional, if you're doing the things correctly in the image capture, you don't need photomerge at all. You should be able to take both images and overlay them in Photoshop, bump moving using the arrow keys until they are aligned exactly and blend the layers together (maybe with a bit of gradient transparency mask). I've done this using images scanned on a flatbed scanner, but auto-align layers is less tedious. I'd also recommend the use of a macro slider to move your camera, if you don't already have one.
     
  9. ced

    ced Member
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    Put a link to two images for those that want to test themselves ( I would ) and invite others to see if they have a solution.
     
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