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What is the highest quality scanner I can buy?

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  • 18-08-2020 8:21pm
    #1
    mr_fegelien
    Banned (with Prison Access) Posts: 1,483 ✭✭✭


    I have a HP Scanner and Printer but it can only scan a maximum of images at 1200 DPI. I'd like something between 2400 - 4800 DPI. Is that possible?


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    #2
    L1011
    Registered Users Posts: 68,806 ✭✭✭✭L1011


    Unless you are scanning very high quality negatives or slides, you do not need more than 1200dpi. However it takes seconds to find 4800dpi scanners

    Also note that it will take up to 16 times as long to make a 4800dpi scan than a 1200dpi one; as well as the file size being massively increased.


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    #3
    5uspect
    Moderators, Arts Moderators Posts: 10,518 Mod ✭✭✭✭5uspect


    Also just because the advertised dpi is higher doesn’t mean the scanner can fully resolve it. The diffraction limit is a thing.


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    #4
    mr_fegelien
    Banned (with Prison Access) Posts: 1,483 ✭✭✭mr_fegelien


    5uspect wrote: »
    Also just because the advertised dpi is higher doesn’t mean the scanner can fully resolve it. The diffraction limit is a thing.

    What do you mean?


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    #5
    L1011
    Registered Users Posts: 68,806 ✭✭✭✭L1011


    mr_fegelien wrote: »
    What do you mean?

    Quite advance optical science about how precise a resolution can actually be obtained by a specific wavelength of light. At 4800dpi you are down to ~5μm per pixel sampled. This is still a lot larger than the limit at visible light wavelengths of absolutely perfect optics, but your scanner won't be using perfect optics.

    But massively oversimplifying it, a cheap scanner can give you a file that says its 4800dpi but not have anywhere near precise enough optics to actually provide that.


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    #6
    5uspect
    Moderators, Arts Moderators Posts: 10,518 Mod ✭✭✭✭5uspect


    mr_fegelien wrote: »
    What do you mean?

    You can only focus an image so sharply. Throwing moar sensor resolution at it isn’t going to help.


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