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  1. #11
    ronlamarsh's Avatar
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    coverage

    I used the online pinhole calculator and for that focal length and pinhole diameter coverage at the film plane will only be 6.65in. The only way to get more coverage would be to move the film plane back.
    No escaping it!
    I must step on fallen leaves
    to take this path

  2. #12
    NedL's Avatar
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    Quote Originally Posted by marciofs View Post
    There was a tape near the pinhole that was making this edge not circular.
    But the problem is that the box is too narrow which places the filme too near the hole.

    I am looking for a box which I can have 7x9in but I can't find any that will be deep enough to avoid vignetting. When I find it is too bit.

    Maybe I will have to make a box with woods.
    This happened to me. I spent too much time looking for the right box and then finally I just made one out of matboard. It seemed a little silly to be making a cardboard box, but once I sat down and went at it, it did not take very long and I ended up with what I wanted.

  3. #13
    SMBooth's Avatar
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    But to compare, Jimmy over at f295 has built a 8x10 /70mm and gets full coverage. Perhaps the thickness of your front face is creating the vignetting.

    Check it out http://www.f295.org/main/showthread....8x10-in-Nantes

  4. #14
    DWThomas's Avatar
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    Quote Originally Posted by ronlamarsh View Post
    I used the online pinhole calculator and for that focal length and pinhole diameter coverage at the film plane will only be 6.65in. The only way to get more coverage would be to move the film plane back.
    I assume this is from "Mr. Pinhole." There's a lot of info at that site, so maybe it tells us somewhere, but my complaint is that there are assumptions behind those calculations and I don't see what criteria he uses. Presumably the coverage is based on some level of exposure fall-off, but it doesn't say what.


    In a quick pass i get the (diagonal) field of view of the OP's camera as 117º. That is quite wide, and yes, there will be fall-off. But here's one on paper from my 4x5 with a 103º FOV:

    Click image for larger version. 

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    (Scanned and inverted)

    Mr. Pinhole seems to think this should be 4.69 inch coverage but what you see is actually over six inches. The camera has a 0.30 mm pinhole at 62 mm from the film/paper.

    (Further edit):
    I've not seen what the OP's pinhole plate actually is. The shot I show here is a hole done by dimple-and-sand in 1 mil brass shim stock -- that's almost a knife edge to begin with. If the hole is made in much thicker stock, the image begins to look like a tunnel view just from the sides of the hole interfering.
    Last edited by DWThomas; 05-15-2013 at 08:58 AM. Click to view previous post history.

  5. #15
    marciofs's Avatar
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    I found a deep box today (180mm) and it is a bit larger than 7x9, which is perfect.

    I have being using coca-cola can aluminium to make the pinhole, but in this case I made the pinhole on the box cover and it may be thicker. I will make a bigger hole and place a pinhole made with cola can aluminium to see if it works.

    I really like Jimmy's idea to put 5 pinholes. I may try it later on.

  6. #16
    marciofs's Avatar
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    A made an other camera easier to load and now it image seems almost perfect.

    I just have to make holdes for the sides bothers because the paper is following off.

    It has a little bit vignetting but after cropping the edges it will be not very evident.

    Click image for larger version. 

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    It has a 0.410mm pihhole
    F-stop: 366
    Focal Length: 140mm

    I load a 9,5x7in paper in the camera but after crop I guess it will be 6x8in. Not bad.

  7. #17
    TheToadMen's Avatar
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    Congratulations: I think you've got it.
    And I don't mind vignetting in pinhole images. It's often a good part of the image, so don't crop to quick.
    Is it possible to show us the image not cropped also?

    You could also pre-flash the photo paper to control the contrast en lessen the effect of vignetting and get more details in the shadow parts. I haven't done it yet myself, but will with the new Ilford Direct Positive Paper I got from Ilford. Here is more info:
    http://www.lesmcleanphotography.com/...ull&article=27 ,
    http://www.apug.org/forums/forum62/6...eflashing.html ,
    http://www.ilfordphoto.com/aboutus/page.asp?n=125 ,
    http://www.apug.org/forums/forum48/9...rd-harman.html.

    Have fun!
    Bert from Holland
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * I'm an analogue enthusiast, trying not to fall into the digital abyss.
    * My favorite cameras: Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

  8. #18
    DWThomas's Avatar
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    Yes! I agree with TheToadMen, you've got it. And yes, sometimes a bit of vignetting helps emphasize the primary subject; it's not necessarily a bad thing. After all, if one wants absolute sharpness and perfection, one would probably go to a lens!

  9. #19
    marciofs's Avatar
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    TheToadMen,

    I only cropped where the paper holder appear. I didn't crop the vignetting.

    DWThomas,

    I think I am enjoying more the soft look of the pinhole than the sharp look of my lens cameras.


    About pre flashing, does it make difference if I pre flash the paper I will do the final (contact) print instead pre flashing the paper negative? Because the first option is easier for me.

  10. #20
    TheToadMen's Avatar
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    Quote Originally Posted by marciofs View Post
    About pre flashing, does it make difference if I pre flash the paper I will do the final (contact) print instead pre flashing the paper negative? Because the first option is easier for me.
    It does make a difference. What isn't in the negative, will never be in the print. Make sure the negative is optimal, then decide what kind of print you'll make. Preflashing the print also is a possibility, but I would do the negative at first.
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * I'm an analogue enthusiast, trying not to fall into the digital abyss.
    * My favorite cameras: Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

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