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Thread: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

  1. #1

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    6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Hi,

    Are there any forum users which use Vuescan on a PC to scan 4x5 negatives at 6400dpi on an Epson flatbed?

    I'm using an Epson V800, latest Vuescan version (on a Win 10 Pro 64 bit PC with 16GB RAM) - and have no problem choosing the 6400 resolution in the interface, but the image files produced are only 3200 dpi. I do get 6400 dpi files from 6x7 medium format without problem. I found a 5 year old thread to this topic here on the forum, but without any clear-cut solution at the time other than scanning parts of the image separately and then stitching them together - which I would be keen to avoid.

    I have increased the 'image memory' size setting in prefs, to more than 9GB, which should be plenty I believe, but without success.

    I do realise that many people suggest that scanning above 3200dpi with the Epson flatbeds won't give you additional image quality, and I do respect that oppinion. I would be keen though to scan at the highest optical resolution possible (6400) and then to reduce file size in PS - even if just to compare the results. So if you have encountered the same problem and managed to solve it, or even if you have just from the beginning been happily achieving 6400dpi at 4x5, it would be great to know your settings!

    Some people might suggest going to a Mac, and I do have that option, but it would simplify things greatly for me if I could get this to work on Windows.

  2. #2

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Quote Originally Posted by kaif View Post
    I do realise that many people suggest that scanning above 3200dpi with the Epson flatbeds won't give you additional image quality
    Several tests show a lower number.

    You might find this article interesting: Scanning Tips with EPSON and VueScan Software. (The link takes you to the section which discusses resolution.)
    Last edited by Ken Lee; 10-Sep-2017 at 11:28.

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Scanning at higher resolutions and downsampling averages the noise in the image so it's not a bad idea. On the other hand I'd be awfully nervous about using the 6400 DPI setting. I just don't believe it's going to give you any better result than 2400 or even 1800. Of course I could be wrong!!!!

    Anyhow, maybe the best thing would be to scan the same image at 1800, 2400, 3200, 6400 and see what the difference is. Then you could see whether there's any merit to using the higher settings or whether you get higher resolution at the expense of lower contrast.
    Last edited by Jim Andrada; 12-Sep-2017 at 11:57.

  4. #4

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    To accomplish what Jim said, you can scan just a small section of the negative at 6400 and should be able to get that to work. Then just compare that same area from your 3200 ppi scan. That should give you an indication whether it is worth your time to continue your efforts to make 6400 work.

    Doug
    www.BetterScanning.com

  5. #5

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Have you tried it with the Epson scan software? It may not be a definitive solution for you, but it'll at least allow you to try out the workflow and see if it's worthwhile pursuing.

  6. #6

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Koraks, just tried this, thank you. Epson scan software doesn't let me select 6400 dpi (well, it does, but then says 'file size too large' and doesn't start the scan.) It does let me select and scan at 4800 dpi, but then it produces a file which Photoshop can't open ('unexpected end-of-file'.)

    Having thought about this all, looking at those numbers, this is all likely based on a bit of a school-boy error on my end though:
    An uncompressed 48bit RGB TIFF at 3200dpi 4x5 gives me file sizes of 1.2GB, a TIFF using compression is just under 1GB. So at 6400dpi, it would be four times that file size, either just above or just below 4GB... which of course is the file size limit for TIFF files!

    With that knowledge: If I set custom resolution on Vuescan to 4800dpi, I do get 4800dpi scanned files which open fine, and are around 2GB.

    At these levels, of course I see some grain in shadows long before I see pixels, and it does all become a pixel-peeping exercise at enormous enlargements to spot any differences at all - so I think I'll settle for that and do some processing to see if I can notice any difference at all further down the editing line between 2400, 3200 and 4800dpi scans. (And yes, I'm very much aware that the consensus is that above 2400dpi, I will likely be hard-pushed to spot any real life gains at all - while resource-hogging will be very real.)

    From what I've learned during this little exercise, I assume that 8x10 users who scan on Epson flat beds would likely max-out at 2400 dpi for single image scan file sizes? Of course you'd very much benefit from the higher film resolution and less grain using only half the enlargement. So in a way, 8x10 sounds like the ideal way to get maximum detail into film-based images for scanning, at least for those of us who are not blessed with drum scanners!

    Ken, thank you for your link. I was interested to read on your website that Epson Scanners work best at multiples of 360dpi. So in high res ranges, would that mean there was likely any noticable advantage in going for, say, 3600 rather than 3200, or 2520 rather than 2400 dpi?

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    ...apologies Ken, of course your website does mention you don't recommend ever going significantly beyond 2400dpi with the Epsons! That might suggest 2160 (6x360) or 2520 (7x360) rather than 2400, going by your recommendation of 360-multiples - did you notice any real life differences at all, going for multiples of 360 at these ranges?

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Quote Originally Posted by kaif View Post
    ...apologies Ken, of course your website does mention you don't recommend ever going significantly beyond 2400dpi with the Epsons! That might suggest 2160 (6x360) or 2520 (7x360) rather than 2400, going by your recommendation of 360-multiples - did you notice any real life differences at all, going for multiples of 360 at these ranges?
    The widely circulated notion is that Epson printers work in multiples of 360 dpi. I never read that about their scanners and would be surprised if that were the case. I suspect that resolution is limited by the quality of taking lens and the ability of the stepper motor to move the scanner in tiny regular increments. After all, this form of scanning is really an exercise in precision stitching. Resolution is often higher in one direction than the other

    If you look at Nathan Potter's graph you can see that the trend line is fairly smooth. Any slight bumps in the numbers with respect to a 360 dot interval (or any interval for that matter) are probably determined by the stepper motor and the software which does the stitching, and are probably below our ability to measure. I have never tried.

    I think the core problem here is that we are struggling to squeeze the last few % out of our equipment, either because it's an adventure to try, or because we are reluctant to upgrade due to cost and inconvenience. We can see a minor improvement with b&w film by scanning the Green channel only (on Epson flatbeds) but if we simply jump to a larger format - or use a better scanner - we will obtain a greater increase in image quality, with far less effort.
    Last edited by Ken Lee; 13-Sep-2017 at 12:05.

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Quote Originally Posted by kaif View Post
    I do realise that many people suggest that scanning above 3200dpi with the Epson flatbeds won't give you additional image quality
    One thing is a shot in the lab, another thing it is a shot in the field. I would be nice to know what % of LF shots have more than 2300 "real dpi equivalent" in film.

    So it depends on the particular shot and film, if shot has some little blur from shake, lens, focus, diffraction etc a higher dpi can be worthless. Also it depends on film, Adox CMS 20 or TMX are sharp films, but it also depends on image microcontrast in textures and silhouette contrast of subjects. TMX resolves 50Lp/mm in low contrast conditions, but 200Lp/mm in high contrast (1:1000) patterns, in the first case a LF lens can be better than film.

    What I say is that depending on the resolving power the negative has it may be useful or not going to 6400 dpi with V800. In general LF negatives are not resolving a lot of Lp/mm, compared to smaller formats, but this depends on your shooting style. Just inspect the negative with a x30 loupe and compare with your scans.

    What's about V800 recommended dpi, horizontal bars and vert bars of a USAF 1951 target have different limits, horizontal bars do not improve beyond 3000 dpi, while vertical bars do improve slightly when scanned at 6400 dpi (from 2300 to 2600 optical), see table C2 here:

    http://archivehistory.jeksite.org/ch.../appendixc.htm


    It should be pointed that 4x5 sheets are scanned with the high res lens of the V800, it scans until 5.9" wide. For 8x10 negatives IMHO it is not worth going beyond 4800dpi, as low res lens is used.

    I practice 4800dpi scanning may be a lot.

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    Peter De Smidt's Avatar
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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    How a scanner interacts with grain can be an important issue, whether or not more scene detail can be extracted from the film. My flatbed isn't an Epson, but scanning at higher resolutions with my scanner leads to a better grain rendition, even though I doubt my large format camera/lens system can achieve the corresponding level of detail on film. So for instance, you might scan a high resolution test target. It gives you a max dpi for your scanner. You might be tempted to scan at that setting, but while that might give you the smallest file size that'll lead to the maximum number of bars resolved on the target, it may not give you the best scan for other reasons, such as grain size...
    "Why can't we all just get along?" President Dale, Mars Attacks

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