Applied Mathematics to Holga Cameras

17

As I like to use science for good Lomographic reasons, let me present you the External Shot counter!

Sometimes, you cannot see the shot N° from the little window behind so I thought to make an external shot-counter. When you roll your film, you turn the wheel of a certain angle to fall on a correct shot position. This angle reduces as the diameter of the roll is increasing. Here, I used an empirical analysis (empirical means by experiment) to determine the good angles (more than 360° rotation before shot 12) needed to turn the wheel in order to make 12 separated shots on any film.

To make measurements of the wheel angles, I placed a white sticker on the wheel, used my Holga normally (by watching shot numbers in the little red magic window) and noted every position of every shot on the sticker. I did this for four films (Provia, Sensia, Velvia and a strange one I forgot the name). Then, I calculated a mean rotation angle over all films to obtain a mean measurement applicable to all films (I hope) by applying a third order polynomial regression. Finally, I produced an external shot counter with Photoshop, printed it, and stuck it on the Holga wheel. I tried it many times. IT WORKS.

As science is about sharing information, I put here a copy of the counter. Print it with the good size, stick it on your wheel and shoot. This is useful when you do 70 mm and you can’t open the red window (‘cause 35 mm are transparent, you know…)… And same thing for 220 film, note that after the twelfth shot, you just make a 360° rotation of the wheel…

written by stouf on 2009-03-29 in #gear #tipster

17 Comments

  1. kylewis
    kylewis ·

    That's fantastic! all beyond me, I think that's why I like random holgaramas... of course all that overlapping is planned!

  2. stouf
    stouf ·

    Oh thanks for publishing that LSI ! I wasn't expecting it... : ) ... And I'd be curious if someone could test it for the Diana...

  3. stouf
    stouf ·

    Oh and if you don't like its design (I'm not good at that stuff) just keep the triangles position and remake you version of it ! Lomo on !

  4. azurblue
    azurblue ·

    Smart idea !

  5. kirri-joy
    kirri-joy ·

    fan-bloody-tastic idea stouf. i always screw up 35mm in my holga, in the end i give up counting clicks. this is great!

  6. kirri-joy
    kirri-joy ·

    this is also great for 3200 ilford b+w...its super hard to see the faint numbers in a dark pub at night.

  7. dogma
    dogma ·

    Cool I love math :)

  8. lomosexual_manboy
    lomosexual_manboy ·

    Stouf, you are a wizard. I'm going to use this for sure.

  9. ebolatheelectricmonk
    ebolatheelectricmonk ·

    Just what I needed! My rule of thumb (1+1/3 turn at the beginning, a little less than one turn at frame 12) works only partly.
    That's much better!!

  10. friskas
    friskas ·

    how about for Diana F+?

  11. itsdebraanne
    itsdebraanne ·

    i'm so confused

  12. stouf
    stouf ·

    @itsdebraanne Mmm sorry to hear that... Here's an example: After you took shot N°1, turn the wheel a full 360° until reaching again mark N°1. Then turn the wheel until you reach mark N°2. You can now take shot N°2. : ) Is that clearer ? : )

  13. itsdebraanne
    itsdebraanne ·

    @stouf i think? haha. do i turn the wheel a full 360 after shot No. 2, then turn to mark 3?

  14. stouf
    stouf ·

    @itsdebraanne: Exactly ! : )

  15. djramsay
    djramsay ·

    fantastic

  16. djramsay
    djramsay ·

    sorry would this work for the 120 wpc?

  17. stouf
    stouf ·

    @djramsay Yep. And I've made one for the WPC (www.lomography.com/magazine/reviews/2011/07/05/holga-wide-p…)

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