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Thread: Newb advice on scanners

  1. #11

    Re: Newb advice on scanners

    Great info Nathan. I agree that the DMAX of the V750 isn't on par with other scanners (NIKON 8000 and TANGO in my comparisons), but I was able to squeeze some more out of mine by boosting the gamma to 3.0. So, if you're interested, give that approach a whirl. The resulting scans look washed out, but capture much greater detail in the shadows than the default gamma, and I can correct for density and contrast in post production.

  2. #12

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    Re: Newb advice on scanners

    Well, a bit more information. I wanted to check the difference between scanning at 1800, 2400 and 4800 SPI. This at the best focus point of my machine which is .110 inch (2.75 mm) above the glass platen. I scanned using the B&W Negative Film setting and Positive Film setting - not significant difference between the two. Used the Toppan glass mask again.

    1800 SPI - 13um scan direction - 17.5 um orthogonal
    2400 SPI - 6 um scan direction - 8 um orthogonal
    4800 SPI - 4 um scan direction - 7 um orthogonal

    The line pairs were read off a printed copy of the mask at about 50 X and the imaged adjusted using levels only in PS. No sharpening anywhere. The logic only being that I wanted to know how fine a resolution could be obtained on print paper with a criteria of a good black line and a clear white space.

    As mentioned previously in a PM to a member, I calibrated the linewidths using a Leitz substage reticle on a Zeiss Axiomat microscope and reconfirmed using a Tencor profilometer matched to an NBS standard - just to be sure of the dimensions.

    Yes, when I get my act together I'll try to post the 50X images - well at least one.

    Nate Potter, Austin TX.

  3. #13

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    Re: Newb advice on scanners

    Quote Originally Posted by Keith S. Walklet View Post
    Great info Nathan. I agree that the DMAX of the V750 isn't on par with other scanners (NIKON 8000 and TANGO in my comparisons), but I was able to squeeze some more out of mine by boosting the gamma to 3.0. So, if you're interested, give that approach a whirl. The resulting scans look washed out, but capture much greater detail in the shadows than the default gamma, and I can correct for density and contrast in post production.
    Indeed, photomultiplier detectors in Aztec machines cannot be beat for obtaining high Dmax values AND lower noise due to the extraordinarily high gain from electron multiplication. (Gains even of a million are possible).

    But a big caveat in all very high resolution scanning is what kind of detail does one have on the original image. Hell, I see under good microscopy, (a Wild M3 binocular microscope) that a lot of my chromes are not better than 15 lp/mm. These are certainly fine for the V 750.

    Nate Potter, Austin TX.

  4. #14

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    Re: Newb advice on scanners

    Thanks Nathan. I understand better now what you have done. The 3600 dpi sounds pretty good to me. Am I correct in reading that the focus point varied over a range from 2.65mm to 3.15mm over a 4x5" scan and that the 3600 dpi is not reliably attainable across the full scan frame? The reason I ask is to help me determine whether it is worth purchasing a focusable negative holder such as that from betterscanning.com.

    BTW...what were you using to support your target plate?


    Steve

  5. #15

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    Re: Newb advice on scanners

    Quote Originally Posted by Nathan Potter View Post
    ...But a big caveat in all very high resolution scanning is what kind of detail does one have on the original image. Hell, I see under good microscopy, (a Wild M3 binocular microscope) that a lot of my chromes are not better than 15 lp/mm. These are certainly fine for the V 750...


    So true! It isn't until we try to go big with our prints that we realize that our images are not really that great in the first place.


    Steve

  6. #16

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    Re: Newb advice on scanners

    If you don't want to throw your V700/V750 out the window in frustration at fuzziness, get the betterscanning holder or something similar. My focus point happens to be 1.8mm above the bed; they are all different.

  7. #17

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    Re: Newb advice on scanners

    Quote Originally Posted by sanking View Post
    For another test of the Epson V700/V750 see http://www.filmscanner.info/en/Films...tberichte.html
    Their tests show resolution of about 2300 spi, which is what I have observed in my own testing of the V700.

    Sandy King
    One thing to consider when interpreting these resolution figures is contrast. A scanner target like the USAF1951 retains very high contrast up to the higher spatial frequencies, much higher than what can be achieved photographically through a lens on film. The overall appearance of sharpness in a scan depends on how well the contrast of the film is modulated by the scanner.

    Even though the V700/750's top resolution for high contrast details might not be that bad at an effective 2300ppi the contrast modulation is extremely soft, at least from the samples I've seen so far. The low contrast details are blurred out from the image. It's very obvious in the samples Steve posted at the Pentax forum. It would be great to see if this scanner can do much better. It's much more significant to see how a scanner performs with a very low contrast target. Take a Tango on the other hand with it's very limited max resolution but being a drum scanner it's still very good at rendering low contrast detail.

    When I tested the resolution of my ICG drum scanner with a scanner target it maxed out at 180 lp/mm which seems impressive. But when scanning photographed resolution test charts (contrast ratio of approximately 1:8) with 35mm film I wasn't able to capture all the detail from the film with my scanner. For example I was able to extract 80-90 lp/mm from the low contrast Fuji Pro 160S while the film holds a little over 130 lp/mm as can be seen under a microscope at 100x magnification.

    What I'm trying to communicate is that low contrast resolution of a scanner is far more important for the overall image quality than scanner target results.

    -Dominique

  8. #18

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    Re: Newb advice on scanners

    Dominique, yes very good points. I've not been able to make any conclusions about the contrast of my V750. Would not even know how to do that. I was at first only interested in the resolution obtainable at any contrast and secondarily how much damage I would do to the resolution by artificially increasing the contrast or employing other digital enhancements using software (Photoshop). As part of trying to figure out what the maximum resolution might be I also looked at the size of the capture pixels at 2400 SPI. These are about 5 um squares as I view them at about 5000X. Thus 2 to 4 pixels are required to characterize a line or space say 8 um wide. My criteria for resolution is that there be, more or less, at least a clear pixel and a black pixel to define a line or a space. Of course all this is quite arbitrary in that the actual pixels as viewed are generated by software so do not, I presume, represent the hardware reality.

    Mark, for the money, this is a very nice little scanner, considerably better than I imagined. I'll keep it.

    It seems to me that for doing wet mounting one will need an intermediate piece of glass in order to raise the film above the platen to the point of best focus. Then the film would need to be held flat using a top piece of glass on the emulsion side of the film. Is anyone doing this?

    Nate Potter, Austin TX

  9. #19
    Peter De Smidt's Avatar
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    Re: Newb advice on scanners

    Quote Originally Posted by Nathan Potter View Post
    <snip>
    It seems to me that for doing wet mounting one will need an intermediate piece of glass in order to raise the film above the platen to the point of best focus. Then the film would need to be held flat using a top piece of glass on the emulsion side of the film. Is anyone doing this?
    You can also get a piece of glass, wet mount the negative emulsion down under the glass, and use shims under each corner of the glass to get the emulsion at the ideal height. The piece of mylar used for wet mounting will need to be fairly large to generate enough tension to hold the negative flat. It's also a good idea to place a mask on the top side of the glass to block extraneous light. Using the preceding method with a Canon 9950F lead to a fairly substantial increase in quality. Doing it with my current scanner, a Screen Cezanne, did not.
    “You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
    ― Alexander Den Heijer, Nothing You Don't Already Know

  10. #20

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    Re: Newb advice on scanners

    The V700/V750 are pretty good scanners. To the point that the drum scan crowd is threatened by them. Keep that in mind perhaps when reading the responses.

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