iPad enlarger

Discussion in 'Misc. Hybrid Discussions' started by RalphLambrecht, Jan 30, 2018.

  1. John51

    John51 Member

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    Any ballpark ideas on what the exposure time would be?

    A purpose built ipad enlarger wouldn't need an adjustable column. Change what's on the screen if you want to crop. Say a Paterson 10x8 printing easel that slides in and out. No neg carrier but a paper carrier instead.

    With the right software, almost all parts of the image can have a separate user defined print density. Don't know the correct term is but section up the image like it's a 'painting by numbers' canvas. Assign a zone/density to each section and the software has the negative be the correct amount of blue and yellow in each section to give the result you wanted.
     
  2. NedL

    NedL Subscriber

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    Not sure about exposure, a wild guess is 3 or 5 minutes.
    Make a positive by inverting the image first, and you could manipulate print contrast locally, by changing the amount of blue or green.
    I was just imagining a cardboard box with a barrier in the middle to hold the pinhole, the ipad at one one and photopaper taped to the other.
     
  3. DWThomas

    DWThomas Subscriber

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    I like it -- sort of an 19thC/21stC slide duplicator!

    (I have an iPad, but too many irons in the fire at the moment.)
     
  4. tezzasmall

    tezzasmall Subscriber

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    I'm thinking of a variation of a 'Johnson postcard enlarger'; a 35mm negative one of which I have but have yet to try out, but I think the principal could be improved upon.

    Terry S
     
  5. hadeer

    hadeer Subscriber

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    An OLED-display has no backlight. So maybe using a Samsung tablet is an idea?
     
  6. John51

    John51 Member

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    The way I would like it to work is the ipad/screen face up and lay the paper on top. Might need something like a fresnel lens in between for sharpness. Sharp enough to make a good print but not so sharp that the individual pixels are visible.

    For the software, some form of Paint type app where parts of the image can be touched up wrt contrast etc. The software could automatically adjust for specific paper brands so WYSIWYG.
     
  7. trendland

    trendland Member

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    Yes - that might be right Ralph....:wink: I am allways happy from good ideas. And shure I often find the time to try out.
    But even not with every idea - sorry.:cry:
    But if your workflow is fine to you - why not ! Different strokes to different folks.

    with regards

    PS : Better telling the truth. ....hmm....?
    OK....I have no iPhone :redface:.
    PPS : My Samsung has just 640 x 480.:laugh::D:laugh::D
     
  8. trendland

    trendland Member

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    Oh nooo - you are talking about iPad's ?
    Well this would change everything.
    (I realy understand this treath as it goes to copy from smartphones)
    Well - iPad is a "tablet - pc" I understand.
    I have an older tablet in 7inch but the resolution is nearly same bad as from phone.:redface::redface:.
    A new model I have on my list is with 2560 x 1600 in 8 inch .....

    with regards
     
  9. John51

    John51 Member

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    Isn't the maximum resolution of paper something like 300 dpi?

    Plenty of screens have that or more.
     
  10. trendland

    trendland Member

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    I would not agree. Photographical paper
    (special in bw) seams to have much more
    resolution as a comparison to digital standard print resolution with 300dpi.
    With the best "retina" resolution of modern screens (or more than retina resolution) you can't notice any dots visualy. But it seams to be allways the question : How much is the lost of resolution via transmitting.
    Think about - the resolution of 35mm film is real high. Cine film hasn't the same format (less than the half) but it is with the same medium (35mm film).
    The most of very competant experts to Cine Film Resolution are stating : " The max. resolution with 35mm Motion Picture Film you are able to reach at the end (in cinema projection) is 2k ????
    That is all ? But 2k is just ~ 2 MP resolution (Full HD 1920x1080) were is the rest of resolution (from Kodak Vision 3 for example) ???
    The answer to this question is simple :
    It is a lost from multible transfers.

    with regards

    PS : Be aware of lost of quality via transfering photographical media it is ALLWAYS imense.
    (exept digital "native" transfers)
     
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    RalphLambrecht

    RalphLambrecht Subscriber

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    Yeah, that's the ideas far PS can do all I need; to figure out the adjustments, I'm using the attached step tablet.
     

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  12. Mr Bill

    Mr Bill Member

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    Color photo paper can go way beyond that, easily 5x more with a high contrast target.

    I once did a demo in the "office," probably 20-some years ago, to disprove some people who said that Kodak 'E' surface paper was severely limited in resolving power compared to glossy. I essentially photographed a line of text that I printed out (via a word processor), at greatly reduced size. It was barely readable under a 5x loupe, but under ~50-100x with a microscope, one could see that the letters were sharp, with crisp edges. The text was small enough to be hidden behind a human hair, which typically has a diameter of 0.002 to 0.003 inch.

    I tried comparing my own cellphone pixels to a human hair with no success; the space between the actual image and the top surface of the screen is enough that one or the other is too out-of-focus to see under a microscope.
     
  13. Eric Rose

    Eric Rose Subscriber

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    All this blather! Can't someone just go ahead and give it a try and show us the results.
     
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  15. NedL

    NedL Subscriber

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    I'll pretty much try anything if it sounds interesting enough. I took this Grimshaw painting:


    upload_2018-2-14_19-24-40.png

    Desaturated, inverted, and colorized it to this:

    upload_2018-2-14_19-25-59.png

    Then I rotated it 90 degrees clockwise and displayed in on my laptop full screen.
    Then I put my laptop in the closet, and put an existing pinhole camera on the keyboard facing the screen.
    It seemed pretty darn bright, so after 1 minute I developed and the paper was still white.
    I tried again using 16 minutes and this is what I got:

    upload_2018-2-14_19-28-47.png

    Looks like it could work if I left it for a couple hours, but I don't want to leave my laptop on w/the same image that long.
    It would probably be possible to account for the light falloff in the pinhole camera, but I don't think I'll fuss with it any more.
     
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    RalphLambrecht

    RalphLambrecht Subscriber

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    I got the Fomalux paper today; will report on results as soon as
    I have any.
     
  17. NedL

    NedL Subscriber

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    I did give it one more try... I had a feeling the falloff was more than just normal for pinhole. I even made the area around the outside a little brighter before I tried. The pinhole idea will not work with my laptop because as the angle to the pinhole increases, the light reaching the pinhole from the screen is reduced. And there are sharp lines where it changes that must have something to do with the pixel structure on the screen. This pinhole camera has complete coverage of the paper, none of this is due to the geometry of the camera:
    upload_2018-2-16_19-31-36.png

    The much darker area in the center must also be a result of the screen... no photograph with this camera has a central spot so pronounced.
    Reminds me of something I read that some lenses made for film SLRs don't work well on digital cameras because the sensor can't handle light coming from much of an angle, whereas with film it matters much less. As I tilt the screen, I can see the light dims a lot, but with my eyes there is no obvious point where it changes suddenly. Could even be something complicated like blue more in the center, then green, then red...