Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,666   Posts: 1,481,710   Online: 745
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 20
  1. #1

    Join Date
    Apr 2009
    Location
    Woodend, Australia
    Shooter
    Medium Format
    Posts
    77

    Pentax 67 pinhole size

    I have a spare body cap for my 67 and would like to play around with making some pinhole images. What size hole would I have to drill into a metal plate embedded into the body cap to get a workable aperture?

    Thanks for any help.

    Mark
    It is said that we remember the important things, if true, why photograph? I forget, so I photograph.

  2. #2
    Jim Jones's Avatar
    Join Date
    Jan 2006
    Location
    Rural NW Missouri
    Shooter
    4x5 Format
    Posts
    1,720
    For best results it depends on the distance between the pinhole and the film. A good free program for determining the pinhole diameter is www.pinhole.cz/en/pinholedesigner/www.pinhole.cz/en/pinholedesigner/. Much information on pinhole photography and camera improvising is at http://www.f295.org/main/forum/ and http://home.online.no/~gjon/pinhole.htmhttp://home.online.no/~gjon/pinhole.htm. Drills small enough for this application are scarce and fragile. Pinholes are often made by slightly penetrating very thin material (usually brass or aluminum) with a needle, sanding off the burr that this produces, and repeating the process until the desired size is reached. It isn't difficult.

  3. #3

    Join Date
    Sep 2007
    Location
    Texas
    Shooter
    Med. Format Pan
    Posts
    351
    Use several formulas for determining pinhole size. They will all be slightly different--- See Eric Renner's book also.

    I had a drill bit for doing pinholes at one pint, and I dropped it on a linoleum floor from about 3 feet and the bit broke into 3 pieces.... that's how tiny and fragile they are. Go for the needle method and measure with a scanner.
    * Just because your eyes are closed, doesn't mean the lights in the darkroom are off. *
    * When the film you put in the camera is worth more than the camera you put the film in... *
    * When I started using 8x10, it amazed me how many shots were close to the car. *

  4. #4

    Join Date
    Sep 2005
    Location
    Istanbul, Turkey
    Shooter
    Multi Format
    Posts
    619
    A nice formula is: SQRT(2.44 x .00053 x focal length in mm)

    For instance, the optimum pinhole size for (say ...) 60mm focal length would be:
    SQRT(2.44 x .00053 x 60) ~= .2786mm ~= 280um

    Note: .00053 is the median wavelength (in mm) of green light.

    Hope this helps,
    Loris.

  5. #5
    TheToadMen's Avatar
    Join Date
    Sep 2012
    Location
    Netherlands, Europe
    Shooter
    Pinhole
    Posts
    930
    Blog Entries
    1
    Images
    19
    Quote Originally Posted by Jim Jones View Post
    For best results it depends on the distance between the pinhole and the film. A good free program for determining the pinhole diameter is www.pinhole.cz/en/pinholedesigner/www.pinhole.cz/en/pinholedesigner/.
    +1
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * "So much time and so little to do. Wait a minute. Strike that. Reverse it. Thank you." (the original Willy Wonka: Gene Wilder, 1971)
    * My favorite cameras: Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

  6. #6

    Join Date
    Apr 2009
    Location
    Woodend, Australia
    Shooter
    Medium Format
    Posts
    77
    Thanks for the replies. Unfortunately I am 100% Mac so the program wont run on my computer. I should have no problem drilling small holes as I've been doing it since I was 15 building scale models out of brass, the smallest hole I regularly drill in 30 thou brass for my model work is 0.34mm (.0135") As best I can measure the pinhole to film distance on my 67 is 55mm (approx 2 1/4 inches)
    It is said that we remember the important things, if true, why photograph? I forget, so I photograph.

  7. #7
    SMBooth's Avatar
    Join Date
    Jun 2008
    Location
    Melbourne, North/West
    Shooter
    Multi Format
    Posts
    926
    Images
    7
    if the film to hole distance is about 55mm then a pinhole diameter of .3mm is fine, your .34 will work fine to just adjust the f stop. That's f183 for the .3mm and f161 for your .34mm

  8. #8
    Poisson Du Jour's Avatar
    Join Date
    Jul 2008
    Location
    Victoria, Australia
    Shooter
    Multi Format
    Posts
    3,377
    Images
    15
    Quote Originally Posted by SMBooth View Post
    if the film to hole distance is about 55mm then a pinhole diameter of .3mm is fine, your .34 will work fine to just adjust the f stop. That's f183 for the .3mm and f161 for your .34mm


    The film plane to inner flange distance would be 55mm, yes. But a body cap adds about 8mm (the Pentax one I have), placing the pinhole further away? I noticed this when I put the body cap on the 67 earlier. Just a thought. I have been mulling a pinhole for the 67 for a few weeks now. Most interesting.
    .::Gary Rowan Higgins

    One beautiful image is worth
    a thousand hours of therapy.


    "It is horrifying that we have to fight our own government
    to save the environment."
    .::Ansel Adams






  9. #9

    Join Date
    Apr 2009
    Location
    Woodend, Australia
    Shooter
    Medium Format
    Posts
    77
    I was allowing for the lens cap. My measurement wasn't exact as I couldn't get the mirror up as I have a roll of film in it. I never have figured out how to fire the shutter without film in the camera even though I've owned it for 20 years, just never needed to!

    Quote Originally Posted by Poisson Du Jour View Post
    The film plane to inner flange distance would be 55mm, yes. But a body cap adds about 8mm (the Pentax one I have), placing the pinhole further away? I noticed this when I put the body cap on the 67 earlier. Just a thought. I have been mulling a pinhole for the 67 for a few weeks now. Most interesting.
    It is said that we remember the important things, if true, why photograph? I forget, so I photograph.

  10. #10

    Join Date
    Apr 2009
    Location
    Woodend, Australia
    Shooter
    Medium Format
    Posts
    77
    Is there any reason not to make a bigger hole so that the exposures are shorter or am I missing something? f161, according to the sunny 16 rule, would be approx 2 second exposure meaning I'm in reciprocity land even on a sunny day!
    It is said that we remember the important things, if true, why photograph? I forget, so I photograph.

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin