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  1. #11
    RalphLambrecht's Avatar
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    be aware that there are two optimum sizes;one for sharpness and contrast;the other for resolution;most viewers prefer the former over the latter.
    pick one and see which you prefer;email me at rlambrec@ymail.com for a more detailed write up.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  2. #12
    StoneNYC's Avatar
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    Does one need to make the ball point pen indent? Or is that just for ease of adding a hole?

    I recently did this with 11x14 x-ray film with a very "unsharp" image. What confuses me is, the exposure came out fairly correctly, so how off can I be and still get an image that's correctly exposed but not fully in focus?

    Lens stats (and "lens")

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    "Quadpod"

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    What I was shooting

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    This is before stripping one side of the emulsion but gives you an idea of the exposure.

    Click image for larger version. 

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    Final image

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    Thanks for any help.
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  3. #13
    StoneNYC's Avatar
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    I should mention, the exposure was 6 minutes and I used a 70nm singer needle to make the hole, the hole should technically be 0.739mm but I figured 0.700 would be good enough, plus with movement of pushing it in I probably made it bigger anyway? Am I wrong? Should I go to the 80nm (0.800mm) needle?
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  4. #14
    DWThomas's Avatar
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    What is the hole in? It is good to have a knife edge around the pinhole. Piercing most materials by pushing in a needle pushes up bits and pieces around the hole. Likewise, if the material is thick (let's define that as a thickness approaching a significant percentage of the intended hole diameter), one is producing a cylinder which is also problematic.

    The classic approach is to press a dimple into a sheet of thin brass shim stock and then sand it with real fine wet-or-dry sand paper used wet. In short, the needle doesn't really set the hole size. So far the best results I've gotten were using the dimple and sand method on 1-mil (0.001 inch) brass shim stock.


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    Last edited by DWThomas; 02-01-2014 at 10:17 PM. Click to view previous post history. Reason: Added a graphic (worth 1000 words?! )

  5. #15
    StoneNYC's Avatar
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    Quote Originally Posted by DWThomas View Post
    What is the hole in? It is good to have a knife edge around the pinhole. Piercing most materials by pushing in a needle pushes up bits and pieces around the hole. Likewise, if the material is thick (let's define that as a thickness approaching a significant percentage of the intended hole diameter), one is producing a cylinder which is also problematic.

    The classic approach is to press a dimple into a sheet of thin brass shim stock and then sand it with real fine wet-or-dry sand paper used wet. In short, the needle doesn't really set the hole size. So far the best results I've gotten were using the dimple and sand method on 1-mil (0.001 inch) brass shim stock.


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    I used foil tape. The kind for metal duct work. So it's fairly thin.
    I did pray paint the back with flat black paint (inside the whole box).

    Maybe I'll sand the back and thin it out and try again with the pen dent trip.
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  6. #16
    StoneNYC's Avatar
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    Quote Originally Posted by StoneNYC View Post
    I used foil tape. The kind for metal duct work. So it's fairly thin.
    I did pray paint the back with flat black paint (inside the whole box).

    Maybe I'll sand the back and thin it out and try again with the pen dent trip.
    Would it be smarter to add the hole from the back so the light is perfectly round on the inside?
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  7. #17
    DWThomas's Avatar
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    Quote Originally Posted by StoneNYC View Post
    Would it be smarter to add the hole from the back so the light is perfectly round on the inside?
    I'm not convinced inside vs outside matters, it's pretty much a symmetrical ray tracing thing.

  8. #18
    winger's Avatar
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    I agree with Dave about sanding a dimple. I usually use parts of soda cans for my pinholes and then color the inner side using a black sharpie. They may not be as thick as brass shims, but they've worked for me so far. I have a loupe with a measuring scale in it (in mm) and have used that to see how round and the size of the pinholes.


    This one was done on Arista lith film (first version, IIRC) using a 0.50mm pinhole (root beer can) 5 inches from the film plane on 4x5. I had better results with the lith than with paper negs (thickness an issue?), but the exposure is off a bit in this one.
    Attached Thumbnails Attached Thumbnails imgc950-2sm.jpg  
    Last edited by winger; 02-02-2014 at 01:56 PM. Click to view previous post history.

  9. #19
    StoneNYC's Avatar
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    Quote Originally Posted by winger View Post
    I agree with Dave about sanding a dimple. I usually use parts of soda cans for my pinholes and then color the inner side using a black sharpie. They may not be as thick as brass shims, but they've worked for me so far. I have a loupe with a measuring scale in it (in mm) and have used that to see how round and the size of the pinholes.


    This one was done on Arista lith film (first version, IIRC) using a 0.50mm pinhole (root beer can) 5 inches from the film plane on 4x5. I had better results with the lith than with paper negs (thickness an issue?), but the exposure is off a bit in this one.
    Way clearer than my image, but I fail to understand how soda can metal is thinner than foil tape... I'll work on it when I get home on Monday.
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  10. #20
    winger's Avatar
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    Quote Originally Posted by StoneNYC View Post
    Way clearer than my image, but I fail to understand how soda can metal is thinner than foil tape... I'll work on it when I get home on Monday.
    Soda cans are thinner than the brass shims that many people use. I have no clue whether they are thinner or thicker than the foil tape. And thinner, but really stiff would be a good thing, too, as then the edges of the pinhole wouldn't be as much of a tunnel - which might be an issue if it gets really thick.

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