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  1. #71

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    I'm very glad to have this invaluable update. I think I will sleep well tonight. Now I really am out of here!
    ZZZZZZZZZZZZZZZZZZZZZZZZZ

  2. #72
    CBG
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    Quote Originally Posted by PhotoHistorian View Post
    PLEASE don't buy an 8x10 enlarger. APUG doesn't have enough file space on their servers to help you accomplish using one. If you can't contact print GIVE UP! My wife and I have taught kindergarteners how to contact print and with excellent results. I can't believe this discussion has gone on for 5 pages!

    Walker
    Like many others, another technophile / techno-victim is thinking and analysing waaaay too much. I would urge the OP take a class somewhere and see the process done.

    Some things really are simple at their essence,

    C

  3. #73

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    hey ic

    i think you must have made a few typos;

    20 sheets of glass would just be silly

    giving foam specific names/serial numbers would be a little too anal, foam is soft and squishy, another named/rated/ numbered foam would be amh, i don't know, soft and squishy

    the fact that you posted all this info leads me to suspect you didn't see the previous posts, is your computer/screen/web browser ok cause you couldn't have read any of those posts

  4. #74
    richard ide's Avatar
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    I am biting my tongue as I ask: Do you work for government?
    I have made well over 50,000 contact prints ranging in size from 4 x 5 up to 60 x 144 and never once has it ever been 95% confusing. I have even used a piece of glass, cardboard and paper clips to make contact prints. Not the best but it works. You are making this 20X more complicated than it needs to be.
    Last edited by richard ide; 10-29-2007 at 10:35 PM. Click to view previous post history. Reason: cancelled bit tongue instead.
    Richard

    Why are there no speaker jacks on a stereo camera?

  5. #75
    Alex Hawley's Avatar
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    Actually, this would best be done using a matrix of strain gages mounted in all three planes (x, y, z) at each corner of the frame, in the middle of each frame member, then a matrix at several points on the back and on the glass sheet. That would allow actual deflections to be be measured. The forces applied and bending moments could be calculated from those direct measurements. Of course that depends on the properties of the frame's materials, so then we get into the type of woods being used, wood grain orientations, saw orientation, and of course, moisture content at time of testing.

    Once the first test is complete, then we can vary the types of woods and joint constructions used in the frame, along with glass types and thicknesses. I'm excited!
    Semper Fi & God Bless America
    My Photography Blog

  6. #76
    ic-racer's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    Yes, math errors.

    Your enlarge can only go 90 mm? That's about 3 inches. I'm sure you meant 90 cm, or 900 mm. That makes your incorrect 0.022 result become 0.0022.
    At least someone read the 'jpg.'

    Interesting error...looks like the enlarger light should perform better than was suggested.

    As far as degree of separation, in the tests I posted it was 'best' at the edges where things were held together in a projection printing frame.

    I think that not accounting for diffraction is an issue but the one of the light passing through the film base is relevant .

    I saw Kodak had some patent for a system with no on-lay glass but it involved using laser light.

    I think I can say that unless I missed something that others are doing, the posts I ran across on NOT using a contact glass may have been with respect to printing "PROOF PRINTS" rather than fine art contact prints.

  7. #77
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    Specific gravity variations in the frame materials would also have a small but not neglidgable effect on the pressure gradients of the system with the possibility of newton ring development at points where the pressure is less than optimum. Newton rings will not form in the close proximity of dust particles of course; which suggests that dust in itself is not a bad thing when carefully controlled in the contact printing matrix.
    Richard

    Why are there no speaker jacks on a stereo camera?

  8. #78
    ic-racer's Avatar
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    Quote Originally Posted by Ray Heath View Post
    hey ic


    20 sheets of glass would just be silly
    20 sheets of framing glass; about a stack under 2 inches high. Pretty much what I had lying around to test as I am still waiting for my thick single sheet from the glass co. As I posted before, isolated pressure on the edge of a single thin sheet bends the glass, so this was the best way I could cobble up to get pressure in the center also.

    As far as the foam goes, Shore A is the rating for the softer foams. McMaster Carr has a conversion chart showing common items like 'mattress' and 'pencil eraser' on their site.

    I suspect not everyone has a Shore guage to measure the foam tires for their RC racing cars, but when you go to order foam from McMaster Carr (or other source) knowing the firmness of something someone has tested and shown to work can help.

  9. #79
    ic-racer's Avatar
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    Quote Originally Posted by JBrunner View Post
    If you first clean the glass of the frame with a cleaner as I do, give ample time for drying.

    I then dust the glass and negative under white light with an anti static brush. I put the negative in the frame, check it again for dust, switch to safe light, take the paper from the safe, place it in the frame, put the back on, expose and process. I have no problems. Comes out as sharp as a contact print. Occasionally I have to spot one that got by.
    Good, this was what I was thinking about trying. Well, I will see how the glass and foam work out and if to much of a hassel, will try the contact frame.

    Now if someone would just donate a nice frame I could end this miserable thread....

  10. #80
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    Quote Originally Posted by ic-racer View Post
    Good, this was what I was thinking about trying. Well, I will see how the glass and foam work out and if to much of a hassel, will try the contact frame.

    Now if someone would just donate a nice frame I could end this miserable thread....
    One thing that you may find is that the contact print frame tends to stay cleaner, for longer, after a thorough cleaning, than the glass and foam.

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