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  1. #21

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    Using the calculator at http://www.mrpinhole.com/calcpinh.php I plugged in the numbers shown below. The numbers were very accurate for the camera that I was designing. I was using paper negatives. The most difficult task (massive quantities of time spent) was designing a "serious pinhole". Thin brass plate seems to be the best material from my own experience and from reading the earliest articles on the subject. The angle of view using those parameters appear close to a normal viewing angle in contact prints made from the 4x5 paper negatives.
    Attached Thumbnails Attached Thumbnails pinholedata.jpg  
    "Lo único de lo que el mundo no se cansará nunca es de exageración." Salvador Dalí

  2. #22

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    Quote Originally Posted by DWThomas View Post
    Methinks accuracy is a somewhat subjective term here.

    One of the formulas often referenced is:

    d = c * sqrt( f * l)

    Where d is the pinhole diameter
    c is a constant (that's where the trouble starts)
    f is the focal length
    and l is the wavelength of the light (more trouble)

    Folks seem to use 0.00055 for the light wavelength (which might be a green) but the spectral sensitivity of the film could come into play. Ortho film would likely produce sharper results if one optimized for the appropriate wavelength.

    The constant --- oooh --- I think Lord Rayleigh, an early tinkerer with these matters, came up with 1.9. But I've seen people using numbers as low as 1.5. Obviously this cauld bend the results quite a bit. In my quick perusal of the MrPinhole calculator, I didn't see an indication of what he used, although it may be lurking there somewhere. Pinhole Designer defaults to .00055 for the light wavelength and 1.9 for the constant, but gives a user the option to edit those values.

    Edit: The 0.0366 is simply bundling numbers, the product of the constant, c, and sqrt( wavelength) for metric values; 0.0073 for inches.

    When one considers the issues of fabrication, pinhole cutting, reciprocity failure and possible film flatness problems, it's probably not worth doing three decimal place calculations here.

    DaveT
    Well all of that makes sense. I actually did some research on the subject and found an article mentioning Rayleigh and some of the physics involved, including wavelengths of light and the constant and what the constant meant. I had an allergy headache from mowing grass, so none of it really made much sense. I printed it out, and I'll read it again tomorrow.

    Maybe I shouldnt research too much on this subject. Perhaps I should just take the recommendations of the pinhole calculators, not worry about all the physics, and just have fun.

  3. #23
    Rick A's Avatar
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    Whatever happened to the simple oatmeal box pin hole camera? I made one in college a hundred years ago, and there wasn't all this fuss over all this rediculous math. All we did was paint the thing black inside, cut out for the "lens" cut the stupid steel beer can and drill it and tape it on the box. All the fun is wasted and lost fretting over the math just to get it PERFECT. My daughter is thrilled to be just making something that will show results , and allows her to EXPERIMENT with all the variables. IMHO we all spend too much time overcomplicating our hobbies and our lives by trying to be the absolute authority on any given subject(self included). My daughter remindes me daily what a ninny I am for this, when all she is interested in is the "fun" aspect of photography.
    Rick

  4. #24

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    Quote Originally Posted by ralnphot View Post
    Whatever happened to the simple oatmeal box pin hole camera? I made one in college a hundred years ago, and there wasn't all this fuss over all this rediculous math. All we did was paint the thing black inside, cut out for the "lens" cut the stupid steel beer can and drill it and tape it on the box. All the fun is wasted and lost fretting over the math just to get it PERFECT. My daughter is thrilled to be just making something that will show results , and allows her to EXPERIMENT with all the variables. IMHO we all spend too much time overcomplicating our hobbies and our lives by trying to be the absolute authority on any given subject(self included). My daughter remindes me daily what a ninny I am for this, when all she is interested in is the "fun" aspect of photography.
    Rick
    You got a point there. I might just make one as good as I can without all the math, and then experiment later.

    Trying to figure out all this "rediculous math" is pretty cool, I think (even though math isnt my strong point, and I'm probably spending more time figuring it out than a smart person )

  5. #25

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    Pinhole articles for those who have access . . . . http://books.google.com/books?q=pinh...raphy&as_brr=1

    Some detailed pinhole construction information can be found in this book . . .

    http://books.google.com/books?id=d_B...raphy&as_brr=1

    Fuzzytypes . . .
    http://books.google.com/books?id=Gds...s&lr=&as_brr=1

    .
    Last edited by DannL; 06-25-2009 at 11:12 AM. Click to view previous post history.
    "Lo único de lo que el mundo no se cansará nunca es de exageración." Salvador Dalí

  6. #26

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    Quote Originally Posted by Darkroom317 View Post
    Any idea what size pinhole I would need for 6 x 9 120?
    Also how far would the pinhole have to be away from the film?

  7. #27

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    Quote Originally Posted by WGibsonPhotography View Post
    I have one more question: Would balsa wood be an appropriate material to make a pinhole camera out of (painted, of course)? I think I can get sheets of it at a local crafts store.
    As BetterSense wrote, balsa may not be light tight enough, but that's only a secondary consideration. Blacking it out with surface coatings is easy enough. A couple of coats of primer and flat black paint will fix that. But balsa is pretty flimsy stuff, and cameras get knocked around a lot. Not a good combination. Basswood might be a bit better.
    Frank Schifano

  8. #28
    Greg Heath's Avatar
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    PINHOLE SIZES

    Mrpinhole.com is what I used...

    It calculates it for you.


    here's another cool site..

    http://www.corbis.readymech.com/en


    You can spend a fortune on laser drilled pinholes...and if you have money to spend...go ahead,

    but if you are building a pinhole, go to ace hardware and buy a sheet of (.003) brass... and dimple and sand the hole to the size you need. I used a #10 "between" needle..which was about .017" perfect from the 102mm focal length.

    I built my whole camera out of black foam poster board and used instant glue and hardener from the model airplane shop.

    The camera is a 4x5, and takes pretty good shots. I have posted some in my gallery.

    Here is the link to what and how I built it.


    http://gallery.me.com/kb2qqm#100294

    Yea, it's foam...but it works pretty good.

    It is the Earl Johnson special from over on f295.org

    Here's the first shot...


    Greg
    Last edited by Greg Heath; 06-25-2009 at 11:27 AM. Click to view previous post history. Reason: additions

  9. #29

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    I don't want to do the math:

    http://www.pinhole.cz/en/pinholedesigner/

  10. #30
    Greg Heath's Avatar
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    pinhole calculator for the MAC

    http://www.concepthouse.com/products/PinholeCalc/


    (Mac software-works on my intel mac)


    Greg

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