Results 1 to 7 of 7

Thread: 4x5 pinhole help

  1. #1

    Exclamation 4x5 pinhole help

    Hey, everybody (: I posted a while back about a friend giving me his old 4x5 pinhole camera. I love using the ~f/280 lens that's on it, but now I'm interested in getting a new lens with an Aperture of f/2000 for a project that is very very bright with artifical lights.

    Right now the stats of the 4x5 pinhole are:
    An F stop that is somewhere between f/276 and f/287
    A lens diameter of .018inches (.46mm)
    A distance between the lens plane and the film plane of 5 inches

    I guess my questions are:
    1) what diameter lens would I need to get to f/2000?
    2) And what would that do to my field of view?
    3) Would it be easiest at this point to just slap on an ND filter?

    Thank you all so much in advance ❤️

  2. #2

    Join Date
    Nov 2017
    Posts
    260

    Re: 4x5 pinhole help

    I'd go for 3, if needed combined with slower film.
    Expert in non-working solutions.

  3. #3

    Join Date
    Jun 2015
    Location
    Anglesey, North Wales, UK
    Posts
    410

    Re: 4x5 pinhole help

    suggest program "Pinhole Designer" which enables all variables to be considered
    regards
    Tony

  4. #4
    Jim Jones's Avatar
    Join Date
    Aug 2006
    Location
    Chillicothe Missouri USA
    Posts
    2,714

    Re: 4x5 pinhole help

    The present pinhole diameter is near optimum for that focal length. The optimum diameter depends on focal length. The more the diameter deviates from optimum diameter, the less sharp the image will be, although the field of view will not be greatly changed. A ND filter is the best option. I've also tried B&W film, fully exposed and developed. placed in close contact with the fresh film.

  5. #5

    Join Date
    Jan 2019
    Posts
    77

    Re: 4x5 pinhole help

    You have an f/280 pinhole. You want to get to about f/2000. This is about a factor of 7-8 in f-number, which is about 6 stops of exposure. You need two 3-stop ND filters, or something like a red filter and a 3-stop ND filter.

    An f/2000 pinhole will be unsatisfactory. There are two reasons.

    1. f-number is focal length divided by pinhole diameter. Your focal length is 5 inches = 127mm. You will need a 0.06 mm pinhole. This is not easy to manufacture and it would need to be in a sheet of material that is less than 0.06mm thick to avoid vignetting (mylar?)

    2. The images from a f/2000 pinhole will be lousy due to diffraction. The blur circle due to diffraction is roughly 2 * f-number * wavelength of light. Use about 500-550 microns for wavelength of green light. For your f/280 pinhole, the blur circle is about 0.28 mm, which will make a reasonable contact print. For the f/2000 pinhole, the blur circle is about 2 mm, 8 times larger, which will look really blurry.

  6. #6

    Join Date
    Jun 2017
    Location
    Corvallis, OR
    Posts
    558

    Re: 4x5 pinhole help

    Quote Originally Posted by Jim Jones View Post
    The present pinhole diameter is near optimum for that focal length. The optimum diameter depends on focal length. The more the diameter deviates from optimum diameter, the less sharp the image will be, although the field of view will not be greatly changed. A ND filter is the best option.
    This is good advice, and Jim is quite correct: smaller hole size will only result in loss of sharpness. You have nothing to gain by making a smaller pinhole.

  7. #7

    Re: 4x5 pinhole help

    Seriously floored by the wonderful responses. Thank you all for taking the time to answer my crazy pinhole questions!!!

Similar Threads

  1. 4x5 Pinhole vs. 8x10 Pinhole
    By Jim Becia in forum Cameras & Camera Accessories
    Replies: 1
    Last Post: 17-Jul-2013, 10:27
  2. PINHOLE
    By Paolo in forum Style & Technique
    Replies: 4
    Last Post: 24-Mar-2005, 15:53

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •