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Thread: Epson v750 - optimum resolution

  1. #1
    twise
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    Epson v750 - optimum resolution

    I recently acquired an Epson v750 scanner and am trying to find the optimum height of the film holders.

    To that end, I have scanned the same image (4 x 5 bw negative) @ each of the 3 levels of the Epson film holder.

    Each scan was identical in process, in that I used Epson Scan, set the output levels @ 0 - 255, set the resolution at 2400 dpi and used no sharpening.

    I printed each image (an 8 x 10 detail from the scan) in Lightroom on Red River Ultra-pro Satin using Eric Chan's ABW profile for this paper. The print was done on an Epson 3880 @ 360 dpi with no enlargement needed.

    I was anticipating differences in the apparent sharpness of the prints, but even using a magnifying glass, I cannot perceive any distinction between the 3 prints.

    I am hoping to get input on the following:
    1. Should I see obvious differences in the apparent resolution of the 3 prints?
    2. If the answer to #1 is 'yes' then what might I be missing in my workflow that prevents me from observing differences in apparent resolution?

    Thanks for any info you can provide

  2. #2

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    Re: Epson v750 - optimum resolution

    I would look at the files at 50% or 100% rather the prints, scanning at 2400dpi. The side by side should be obvious at that magnification.

  3. #3
    Joanna Carter's Avatar
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    Re: Epson v750 - optimum resolution

    You might like to also consider that, depending on the accuracy of manufacture of the scanner (not always that reliable), the sharpest focus may be above or below the range of the Epson holder; which is why some of us use the Better Scanning mounting stations, which are fully adjustable.
    Joanna Carter
    Grandes Images

    UKLFPG

  4. #4

    Re: Epson v750 - optimum resolution

    When I tested my 4870 I viewed at 100% on the screen. It would be pretty tough to see the differences at small print sizes. While I didn't print my tests, I'm guessing I wouldn't be able to see the difference in the prints until around 6x or more. That's a moot point for me, as the largest I print with the Epson scans is 16x20, any larger and I get a drum scan.

    Mine turned out to be sharpest with no shims, although it may be sharper if I were to go to a negative setting.

  5. #5

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    Re: Epson v750 - optimum resolution

    + Joanna. As an example, my optimum height with the Epson holder (using washers) was 3.75mm. Subsequently confirmed with the BSH.

  6. #6
    twise
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    Re: Epson v750 - optimum resolution

    Thanks for everyone's reply to my query.

    At the risk of belaboring the point, I have attached 4 files that are details of the three scans I made, changing the height of the film holder for each, and a thumbnail of the whole image for context. These are reductions of original files that are 100% views with no interpolation. I still cannot see significant differences between the 3 close ups.

    I followed Harley Goldman's advice & viewed the images @ 100%, but could only discern subtle differences.

    What I do wonder about at this point is if, as Joanna suggested, the area of sharpest focus might be above or below the range of the Epson film holder

    I followed the same process for each scan, thinking that any differences seen would be a result of changing the height of the film holder.

    As an aside, the initial photo was a response to an assignment given in an LF class in the local community college where we were supposed to illustrate the theme of 'Greed'.

    Thanks for your input
    twise
    Attached Thumbnails Attached Thumbnails Hi Pass Det.jpg   Mid Pass Det.jpg   Lo Pass Det.jpg   Res test thumb.jpg  

  7. #7

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    Re: Epson v750 - optimum resolution

    Optimum height is typically between 3 and 4 mm above the surface of the platen. I made a plot of the resolution vs the image height using a high resolution wedge mask a while back. It is posted here somewhere. Well let me grab it and I'll repost. I gives you an idea of the depth of field that you can expect. Perhaps you did not vary the height substantially enough to yield definitive results.

    Nate Potter, Austin TX.


    V750RESjpg by hypolimnas, on Flickr

  8. #8

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    Re: Epson v750 - optimum resolution

    A computer monitor is a poor tool on which to judge critical sharpness so I think you were right to make prints. But FWIW, when I open your three test files in Photoshop and view them side by side at 450x450 it looks to me like your LoPass is somewhat sharper than the other two.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  9. #9
    Richard M. Coda
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    Re: Epson v750 - optimum resolution

    Excuse me for being ignorant... but how do you change the "levels" of the stock Epson holders? Thx.
    Photographs by Richard M. Coda
    my blog
    Primordial: 2010 - Photographs of the Arizona Monsoon
    "Speak softly and carry an 8x10"
    "I shoot a HYBRID - Arca/Canham 11x14"

  10. #10
    Jon Shiu's Avatar
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    Re: Epson v750 - optimum resolution

    Excuse me for being ignorant... but how do you change the "levels" of the stock Epson holders? Thx.
    There are feet on the Epson holder and you can adjust to 0, +, or take them off. It is in the pdf manual, buried under what to do if you get blurry scans.

    Jon
    my black and white photos of the Mendocino Coast: www.jonshiu.com

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