Less is pinhole

Discussion in 'Pinhole Photography' started by Kinetic, Oct 5, 2011.

  1. Kinetic

    Kinetic Member

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    A trip with Obscura.
     

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  2. Kinetic

    Kinetic Member

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    2nd part.
     

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  3. Kinetic

    Kinetic Member

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    Hope you guys have some tips for me.I want improve it more.I think now it's all about the focal length, because now I use a real pinhole, made from a cheap chinese watch.It is from metal , very thin, and has the perfect small hole, sort of ~0.4mm.
    I really love my Obscura camera.Next film that goes in must be better than this one , wish me luck! :smile:
     
  4. Romary

    Romary Subscriber

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    What is the focal length?
     
  5. Kinetic

    Kinetic Member

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    Sort of ~ 50mm-51mm.I just have to go closer or further.Tricky!Any advices?:smile:
     
  6. bsdunek

    bsdunek Subscriber

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    Looks like your effective f-stop is about f125. In my experience, I find that you need at least f200 to get a reasonably sharp photo. Just a suggestion.
     
  7. steven_e007

    steven_e007 Member

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    Your pictures are very soft. Pinhole pictures are always a bit soft - and maybe this is what you want?

    But if you want sharper - there is a mathematical relationship between the hole to film distance and the diameter.
    The idea is that the circle of confusion gets smaller as the diameter decreases, but as the diameter decreases diffraction gets worse, so there will be some ideal compromise diameter for best sharpness.

    If you use the formula d = SQR( F/k)

    where F = film to hole distance, and k is a constant, about 1300.
    (SQR means square root)
    Different people use different constants and formulas, but it gets you in the right area.

    For a film to hole distance of 50mm - you want about a hole diameter of about 0.2 mm, I reckon.

    Or... to work that backwards from a hole size of 0.4 mm, F = (0.4*0.4) * 1300 = 208.

    So, I reckon that pinhole is ideal for being about 200 mm from the film. (If I've got my maths right?!!!)

    What size film are you using? That would be a 'Normal lens' on 5 X 4"
     
  8. Romary

    Romary Subscriber

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    I do not believe in the formulae for the holes there are more than 50 formulas for that hole. All these formulas give very differente result with a sometime a factor two betweens the results. I wrote an article in my blog with formula from various great specialists of optic, physics etc which give totally deferent results. The article is in franch, but you can have a look at the fomulas and the curves)

    But saying that, that does not means the size of the hole is not important. If you want a sharper results, 0.4 mm for a focal length of 51 mm seems to me a bit too big. A hole with a diameter of 0.2 or 0.3 mm should improve clearly the results in term of sharpness.

    Second thing, you said that you used a part of a Chinese watch. How thin is the material. I doute it is a thin as for example a piece of beverage can. The thickness is clearly also important (an taken in account in the formulas).
     
  9. jnanian

    jnanian Advertiser Advertiser

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    pinhole or any "soft" image enlarged ..
    require a larger viewing distance.
    the thumbnails look sharp as nails,
    and if you take a few steps back
    the enlarged jpg's look nice as well
    from a distance ..
    nice work !
    my only suggestion would be to make the images less "tippy"
    unless angled composition is what you were going for :smile:

    have fun !
    john
     
  10. SMBooth

    SMBooth Member

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    Your exposures look ok so what ever exposure calc your using is working for you. At 50mm a .3 pinhole is around the right mark so your .4 is not so far off to worry greatly. I would expect sharper pinhole image for this setup unless you where not using a tripod or other support. Maybe the material of the pinhole is to thick, I use a soft drink can and sand in back with some 1000grit wet and dry sandpaper. If this effect, which is not unpleasant is what your looking for then keep going.
    f295.org is an active pinhole site that you may wish to visit as well.
     
  11. bsdunek

    bsdunek Subscriber

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  12. Kinetic

    Kinetic Member

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    My piece of metal comes from a watch.Pretty thin but I can do better.I am still looking to find this type of parts of metal with tiny perfect holes.I am knew in photography, of course in pinhole too.Thank you for your advices, I will try to go over all of them.Maybe I can make my images sharper.
    I use b&w 5mm ISO100 and colour film for ISO200.I got to feel what exposure I should use.About the composition, well it's harder.I just guess where the camera points at.And I think my angle of view is ~44.6degrees.
    I just bought a Zenit E from an antiques sale, street market.Works perfect.I try to use it to see what the angle looks like in my viewfinder.I point and shoot and in my mind I have that composition for my sight, my 37 degrees angle.Sometimes you have to guess.
    I went to many sites but still it is too hard to real use that info about your pinhole with your own, it is too hard to measure it or make it a perfect circle.That bugs me.BUT, what I love about this thing is that I will try to improve mine until I get it right!I am too close to having a perfect pinhole camera :smile:.And of course, I love what I am doing.

    Less is pinhole!
     
  13. nhemann

    nhemann Member

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    A note on measuring your pinhole diameter - you can scan the image at a high resolution (2000 dpi or so) enlarge the hell out of it and then use a graphics editor - Adobe etc, (GIMP is free) to determine the number of pixels the hole is. Based on your scan resolution you can determine what the per pixel width is and, in turn, the actual pinhole diameter. I've checked my holes with a microscope and and its proved to be a pretty darn accurate method.
     
  14. vpwphoto

    vpwphoto Member

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    Not "hating" as the younger folks say... but those photos are just too soft for me to have any interest in.
    Do what you like though.
    Cheers.
     
  15. Tom Miller

    Tom Miller Member

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    Two points. First, my guess is you mean 35mm. In my experience, and for what I try to accomplish via the pinhole medium, 35mm is too small of a negative to enlarge cleanly. They always look fuzzy. Try 120 film either with a home-made, converted or purchased camera and the enlargements will be much more clear.

    Second, I suspect that the watch metal is thick enough that you are getting the "tunnel effect." Light bounces off of the sides of the pinhole itself causing diffusion. Here is a link to a thread on f295 where Earl Johnson sells electron microscope slides mounted for use as pinhole. They are excellent, with thin metal and precise apertures; and they are cheap. I use them for nearly all of my own photos.
    http://www.f295.org/Pinholeforum/forum/Blah.pl?m-1283887930/s-all/
     
  16. ced

    ced Member

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    Kinetic! I think your images would have been even better for me if they were sharper (less Blurred).
    I think the 0.40 is too big and 0.30mm might be a safer bet to get more details.
    I am no expert but from browsing the web my gathering is that this hole should be smaller and there is an optimal which I am also hunting for.
    I have been on 4 different sizes myself but still not happy.
     
  17. Kinetic

    Kinetic Member

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    Hard to get a perfect pinhole size, but I am sure trying :smile:.Who has some old chinese watches that they do not use any more? :smile:)
     
  18. dasBlute

    dasBlute Subscriber

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  19. narsuitus

    narsuitus Member

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  20. Kinetic

    Kinetic Member

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    I still don't how to use the paper or larger formats.I have no darkroom and no room for one.And don't know where to go and take them out.And it's too bad, I know, but what can I do? I just use my Obscura as it is and hope for the better.Looking for smaller holes in metal sheet.:smile:)
     
  21. ced

    ced Member

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