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Thread: scanner camera works!

  1. #11
    Administrator Tom Persinger's Avatar
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    scanner camera works!

    you tried GIMP staft?
    free and relatively painless install.
    full featured

    http://www.gimp.org/macintosh/

  2. #12

    scanner camera works!

    staft, feel free to PM me or IM me on AIM (HulaCrab). I got SANE + TWAIN working on OS X last night and will be happy to supply the necessary installer files.

  3. #13

    scanner camera works!

    Wheee!!

    It's so much fun watching geniuses work together.

    Staft, I agree with moot -- you've been sandbagging all this time. BTW, you don't really need 8.5x11 gels, they only have to be big enough to cover the lens. And you can probably use the glass from the original scanner to make your ground glass, though you'll probably want/need to mount it separately so you can get the correct spacing and have the ground glass focus match that of the scanner sensor. I'd suggest Lee theatrical filters for color correction, and I think they sell neutral density as well, but that's a B&W only scanner, isn't it -- red LED light source! -- so you could get away with multiple layers of any non-red filter material. Assuming you have a local Lee dealer (and you probably do), you can get a 20x24 sheet of filter material, which you can cut with scissors to make a couple dozen lens-size pieces (stack 'em to get the exposure you want) for $7+.

    http://www.leefiltersusa.com/index.htm

  4. #14

    scanner camera works!

    Repromaster, Staeble, Helioprint & maybe some other non-boutique name process lenses were almost guaranteed to have been made by Agfa. I filled out an info request form on an Agfa site in German, best guess what fields to fill & what button to push & gtoa response from a Dr-Ingr there with specs on F/8 versions. My Helioprint ones are f9 but those were the specs he sent.

    Roughly 68 degree coverage, roughly 450 mm image circle at 1:1 process distance (2x bellows extension) for 150 mm lens, 650 mm+ for 210 mm lens. Rule of thumb is half that coverage at infinity focus

    I have heard of 210 mm Helioprint being used on an 11x14 field camera with dark corners, so apparently workable at 8x10.

    Rodenstock has more 'brand appeal' among the process lenses, short of Red Dot Artar, etc. rec.photo.large-format.equipment should provide info on that lens or a place to ask.

    Some of them are 6 element planar and some are 4 el double gauss type roughly (Celior?) with greater coverage. There is a version of Rodenstock Geogon that was made for exteme enlargements, but it might be Geogon-X or Gerogon or Gerogon-X...I don't remember.

    Uneven opalescent color might be damaged antireflective coating due to agressive cleaning...Glass is still APO, just avoid flare.

    The 1:1 process distance on those was spec'ed as 1:5 - 5:1. Some work very well, some so-so at infinity.
    Best opticalquality supposedly 2 stops down from open. Specs mostly at f/22.

    When things slow down I'll see if I can find that email with Agfa data. Probably describes the Repromaster lenses better than nothing. My Helioprint ones do not lend themselves to any kind of easy central shutter, but that's probably not meant to be, not my style anyway.

    Murray

  5. #15

    scanner camera works!

    I use rock tumbling grit & water. Cleans up easier than the grease/oil suspension stuff.

    I take a piece of 600 or so grit SiC sandpaper & get rid of any razor sharp edges or both the screen and the grinding plate...got too many fine fingertip cuts the first time I didn't do that.

    I started using 320/400 or 400/500 blend Silicon Carbide...I forget which exactly.

    I then got some 5 micron aluminum oxide because it supposedly is softer & doesn't chip the glass as harshly. Too soft, hardly does anything in the time I want to spend making glass. Also won't get 'waves' outof glass used alone I last used a mix of the SiC and AlOx, no idea what mix, just experimenting. If you play with the super fine stuff, be careful to not get it airborne & inhale it.


    I did a 20x24 with plain SiC just to do it and check out large lens circles (I told you I was easily amused short of shooting film...I'm happy seeing an image on ground glass alone sometimes). I forgot how much more area that was than 4x5...it took a long time to get all the 'bald spots' frosted adequately. I work on it until it LOOKS done, then wash the water/grit mud off with soap & water & hold it up to light to find areas needing more abrasion. Sometimes I mak the back (glossy side) with a red dry erase marker where it needs more work so I don't get lost when I put it back down with more grit.

    I have tried two identical sized pieces of glass and a small piece as a hand tool. I think the small piece method works better for me.

    I work on a flat utility table(NON-FLEXIBLE TOP), mist a sheet of kraft paper to keep bottom lite of glass from sliding, toss a little grit on & mist with a water spray bottle. More water works better than less, as it seizes up pretty quickly otherwise. Maybe the oil-based valve grinding stuff stays slippery. I think the other reason I stayed away from that stuff is a compund in it that you don't want your hands in (triethanolamine?)

    I tried a finishing sander and grit & water once but it was too messy & pretty much made suure I wouldn't be able to use self-adhesive sandpaper in the future.

  6. #16
    Administrator Tom Persinger's Avatar
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    scanner camera works!

    here's a url to making one with valve grinding compound (avail at Sears) it cleans up with water

    http://www.philsan.com/ground_glass.htm

  7. #17

    scanner camera works!

    Would a strip of good quality tracing paper placed over the sensor work?

  8. #18

    scanner camera works!

    Theremin, the ground glass isn't to go over the sensor, it's so the operator can focus the camera before mounting the sensor, and so (hopefully) get an accurately focused scan on the first try. Tracing paper works, but it's on the dim side compared to even pretty badly made ground glass, plus it's hard to keep flat.

  9. #19
    Administrator Tom Persinger's Avatar
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    scanner camera works!

    just posted an overview of my ground glass grinding procedure:
    http://www.f295.org/DIYforum/cgi-bin/forum/Blah.pl/Blah.pl?m-1141700672/

  10. #20

    scanner camera works!

    I am so very happy to find someone else who has built one of these and thank you for documenting it. And also all those who commented, some good information (I too broke first sensor.).

    The last problem that I am trying to solve is what appears to be the reflection off of the center stainless steel rod (I posted info on my unit yesterday and also used Canon LIDE). I have been using only clear part of scan and am considering constructing a fixture to hold the scanner so lens is centered over one half of scanner and rod will not be in center. Any ideas?

    I will try to attach a photo - I am very new at working on this site...

    Update, I have tried numerous experiments relative to center shadow. It may have just been consistantly underexposing or a light leak I discovered from scanner light source that I thought I had completely blocked. Anyway, the problem seems to have gone away.



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