Questions on my first pinhole - 8x10

Discussion in 'Pinhole Photography' started by yeknom02, Apr 1, 2011.

  1. yeknom02

    yeknom02 Member

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    Hi guys, I was thinking of trying to build an 8x10 pinhole camera this spring. Probably made out of wood, and something with a fairly "normal" focal length, to be a general-purpose large-format camera that's really easy to work with.

    1) I want to shoot 8x10 paper negatives. Should I plan on making a camera based on an 8x10 film holder, or will paper not fit in a holder? If not, what would be an easy way to load the camera?

    2) I've heard that paper negatives need low contrast. Can I put an Ilford 0-grade filter behind the lens to help with this?

    3) How accurate does the hole-to-film-plane distance need to be?

    4) Any tips coming to mind from past pinhole-building experience that I can't afford to learn by trial and error?

    I'm going to continue reading up on the subject... Thanks for any pointers!
     
  2. John Koehrer

    John Koehrer Subscriber

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    People have just used double faced tape, installed grooves as they built their camera, anything that you can figure out. Focal length can be anyplace you want, There is an optimum diameter/focal length that can be calculated. There's bunches of information at f295.org
     
  3. David William White

    David William White Member

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    Super!

    1. Film holders really help, if you have some. I fit mine against weatherstripping to make a light-tight seal. You can use the darkslide on the holder to 'strip test' (ie. bracket) your first few test exposures. You will need to give the paper a small trim to fit the holders, but that's no biggie.

    2. Yes, or any old yellow filter, but likely in front of the pinhole -- just to protect it from the elements. Alternately, you can shoot on overcast days when the contrast is lower, or you can pre-flash the paper a wee bit. Softer developers (diluted Selectol-Soft) are also an option.

    3. For best results, the pinhole should be sized according to the so-called focal length. So for a 10" distance, you'll need a pinhole in the neighbourhood of 0.6mm.

    4. If you are proceeding with a 'normal' focal length, you might want to fit a wire frame or suchlike to aim the beast.

    Have fun!
     
  4. Jim Jones

    Jim Jones Subscriber

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    2) You can also reduce contrast by altering the developer and development time. Solarol developer gives low contrast, but reduces the effective speed of the paper.

    3) not at all precise. The recommendations of optimum focal length for a specific pinhole diameter vary over a wide range. I prefer Pinhole Designer http://www.pinhole.cz/en/pinholedesigner/ with a constant of 1.5. Mr. Pinhole is another popular calculator.

    A site with much information is http://home.online.no/~gjon/pinhole.htm. The definitive reference book is Eric Renner's Pinhole Photography.. The definitive reference book is Eric Renner's Pinhole Photography.
     
  5. yeknom02

    yeknom02 Member

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    David, what do you mean by a wire frame to aim the camera?

    Is a 0.6mm pinhole easily manufactured with a needle or am I going to have to turn to precision-manufactured pinholes?
     
  6. yeknom02

    yeknom02 Member

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    Jim, thanks for your recommendations. Eric Renner's Pinhole Photography arrived today and I'm currently looking through it.
     
  7. David William White

    David William White Member

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    If you look at a Speed Graphic (& similar), they have a pull up wire frame on the front standard that's used with a sight on the rear standard to aim the camera, and a crosshairs on the front wire frame will give you both centre and frame coverage. Similar to 'sport finders' on TLR's and such. I only mention because most pinhole cameras are ultra wide angle, where aiming isn't so much of a concern. If you're going 'normal', you might wish to rig a finder of this sort.

    (Another option is to have a simple lens on the front, some glassine or vellum paper for a ground glass, line everything up, then replace the lens with your pinhole and the glassine with your paper holder.)

    Depends on how much sharpness and resolution to want, your artistic vision, etc. You can poke holes in tinfoil with a #8 needle, examine each in your enlarger to find the cleanest one, or just be a lot more fast and loose. Slits are fun too.

    D.
     
  8. aaronmichael

    aaronmichael Member

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    Unless you want vignetting, you want to make sure that the focal length projects a big enough image to fill up your entire 8x10 negative. Longer the focal length = larger the image. I made an 8x10 pinhole camera a couple months ago and just tape the paper to the back. This was because I don't have the skills to make something that could take a film holder - haha. I third or fourth what everyone else says about the yellow filter, seems to work well for me. Just be sure to add a stop or so of exposure time to compensate. Also move the yellow filter around during the exposure so your image doesn't have dust specs on it that are on the filter. I use aluminum from soda cans to make my pinholes. Cut the can up then use an orbital sander to shave it down even more thin. Poke a small hole through with a sewing needle, sand down the burr on the other side. Not to get into the topic of scanning but if you want to be real accurate, you can scan and measure the diameter with a photo program. Also, one of the things that helped me out the most was an exposure formula that another user on here gave me. I'd give credit if I could remember his user name. The formula is:

    Tc = Tm (Fc/16)^2

    Where Tc = Correct exposure time, Tm = Exposure time metered at f/16, and Fc = Focal ratio (equivalent to the aperture number of your pinhole). And then of course you need to add time on top of that to compensate for papers slow ISO. I attached a picture of my 8x10 pinhole camera and a recent photo I took with it.

    [​IMG]

    http://www.flickr.com/photos/aaronmichael/5533307599/
     
  9. bvy

    bvy Subscriber

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    I second Renner, and I'll add Mr. Pinhole as an invaluable resource -- especially as it relates to finding an optimum pinhole diameter for a given "focal length" (or vice versa):
    http://www.mrpinhole.com/
     
  10. Jim Jones

    Jim Jones Subscriber

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    Making pinholes isn't difficult. I recommend .002" brass shim stock, available in many hardware or perhaps auto supply stores. Aluminum is popular, but isn't as nice to work with. I've also used very thin stainless steel where small precise pinholes were needed, but it is difficult to work with. Measuring the size can be more difficult for some. Eric Renner's book gives several methods for this. For a perfectionist, pinhole diameter should be within five or ten percent of the design size. Pinhole photography is quite forgiving of imperfection. We do better when we concentrate on making the best possible photograph with whatever camera we use than when we merely concentrate on making or buying the best possible camera.
     
  11. Tom Miller

    Tom Miller Member

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    Well stated, Jim. The joy of pinhole is paramount.
     
  12. yeknom02

    yeknom02 Member

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    True, but since I'm an engineering student during my "day job," I find that the extra effort you can put forth in the fabrication process to be very enjoyable as well!
     
  13. Klainmeister

    Klainmeister Member

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    I built my pinhole by cutting a Pabst can and sanding the surface as thinly as possible and using a needle to make a tiny prick. Then I scanned the pinhole on my scanner and measured it in photoshop so I could figure out the rest.

    Just some thoughts. And for the record, it's actually almost too sharp. Kinda funny.
     
  14. Jim Jones

    Jim Jones Subscriber

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    I agree. On http://www.f295.org/Pinholeforum/forum/Blah.pl? you can find cameras that are better works of art than the photographs they are apt to produce. Engineering at its best is as much an art as anything. However, it's nice when pinhole cameras, like other engineering projects, are also functional and put to good use.
     
  15. pgomena

    pgomena Member

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    I played with pinhole photography for a couple of years and can only say that it really is a lot of fun. I never cease to be amazed that so simple a contraption, made with a reasonable amount of care, can produce such amazing results, and so cheaply!

    I have a couple of ancient, slightly warped 11x14" film holders a friend gave me a few years ago. Some day they will be put back to use in a pinhole camera. Should be tons of fun!

    Peter Gomena
     
  16. Joe VanCleave

    Joe VanCleave Member

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    I just came back from Arches National Park after exposing about 18 paper negatives in the 8x10 format. It was a blast, very satisfying photographically. Many of the OP's questions have already been answered, so I'll just add a few thoughts.

    Film holders: 8x10 fits nicely inside 8x10 film holders without any trimming of the paper required. This is not true with the 4x5 format. Carrying, say, four 8x10 holders in a backpack can, however, add significant weight if you're out on a photo safari like I was. Which brings me to my next thought...

    Box cameras: The camera I've used for my last two photo vacations is an 8x10 box, made from black foamcore board and gaffer's tape, that's fairly wide angle in view. It uses "viewing dots" on the sides and top, which form triangles whose vertices are adjacent to the pinhole and edges of the film plane, giving one a pretty accurate method of framing one's images.

    The major features of this particular box camera are that there's a side-opening lid, giving access to the interior, and a storage area behind the film plane, where exposed and unexposed paper is kept. Prior to leaving for my trip, I grabbed a stack of paper (about 1/4" thick, maybe 40-50 sheets) and slipped them into the rear-most storage slot. Then, when out in the field, I insert the entire box into a changing bag (which I carry inside my backpack) and load one sheet into the film plane.

    Thus, this box camera doesn't use sheet film holders, yet permits me to carry (theoretically) more than a hundred shots in one vacation, all inside the one box.

    The film plane is a sheet of galvanized steel, painted flat black, that has had its edges folded over to make film rails, on three sides. Thus, the paper negatives slide in and out easily. Since RC paper tends to bend away from the emulsion, and thus the center of the negative can thus bulge outward, toward the pinhole, you can either use a small piece of double-sided tape to secure the paper from slipping out of the film rails, or use a modified bulldog binder clip along the free side (this is the method I used on my most recent trip, and it worked well). The problem with double-sided tape is that it can sometimes leave debris on the backside of the paper.

    The working method is thus load the paper, compose and shoot, then reload paper. You have to find, between each shot, a place to sit (preferably in the shade) and reload. It does slow down your progress a bit (if you're hiking with others) but it also gives you time to rest, and to contemplate your surroundings while reloading.

    The advantage of this box camera method over using film holders is that it's lighter than carrying film holders, and after the eighth shot, with film holders (assuming you were carrying four such holders) you'd have to return to the car to reload the holders, since they take up more room in the changing bag to reload than does the box camera (you're better off reloading holders with a changing tent), and are harder to reload than the box.

    I should also mention that I received quite a few comments and questions about the camera while on my vacation, affording me the opportunity to be a pinhole evangelist of sorts. Whatever method you use - sheet film holders or a multi-shot box camera - these can be lots of fun.

    Contrast: Regarding control of contrast, I think you end up with a faster Exposure Index if you use low-numbered graded paper rather than filtering multigrade paper. I've done experiments using Ilford MG-RC-IV paper and a yellow filter, and it requires an Exposure Index of below 5; whereas my grade 2 RC paper from Freestyle (their Arista brand) I rate at an EI of 12.

    Exposure/Development: This is real important, to find the proper EI of your paper, and properly expose it. I tend to use a handheld meter, and meter the brightest part of the landscape that I want to retain detail and place it at +1 stop on the meter. Then I reference the exposure time for f/128 on the meter (the highest f-stop that the meter will indicate) and perform the necessary conversion to my camera's f-stop. What I've done in this case is calculate a "k" factor ahead of time, which I've affixed via a label on the back of the camera, which in the case of this particular camera (f/258)is "4x". Thus, if the time adjacent to f/128 on the meter is 15 seconds, then the actual exposure time is 60 seconds.

    Note that when metering, I try not to get the sky in the meter's 30-degree angle of acceptance, because I'm not interested in exposing for the sky, but for detail in the landscape.

    Also, if your landscape has lots of red-toned rocks and earth, you need to extend your exposure time further. I usually give an extra stop of exposure in this case.

    I either pre- or post- flash my paper negatives, to improve shadow detail. When loading up the box with a huge stack of paper, it's more convenient to post-flash each sheet prior to development.

    I use the same dilution of paper developer (Ilford's Universal paper developer) diluted 1+15, but also mixed with an older batch that's almost black. When this new batch gets used up, it becomes the old batch, etc. I also ensure that the temperature is around 68f, and develop by inspection until the landscape detail is adequate, rather than sticking to a particular development time. This is important. A slight drop in temperature can significantly increase the development time; you can also somewhat compensate for moderate under-exposure by extending the development time.

    This was somewhat rambling, topic-wise, but hope there's something of value.

    ~Joe

    Atop Delicate Arch, 80 second exposure:
    [​IMG]
     
  17. Rick A

    Rick A Subscriber

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    Joe is the master of the pinhole.