What to take into account as a pinhole newbie?

Discussion in 'Pinhole Photography' started by perminna, Jul 7, 2010.

  1. perminna

    perminna Member

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    I bought a 6x12 Noon Pinhole camera yesterday, the most beautiful piece of crafting I've seen. It should arrive in a week or so. What should I take into account when I start taking my first pinhole photos? The focal length of the camera is 60mm and the aperture is f/207.

    I develop my own film and I'm going to use either Ilford FP4+ or Fomapan 100 as a test roll. I have a tripod and a spirit-level to get the camera steady and straight. I know the final image will be a mirror image of the actual scene.

    Do I need to take something else than normal aperture + exposure time + film ISO into account? The aperture of the pinhole is f/207 so it's about 9.5 stops from f/8. Do I just extend the exposure times by 9.5 stops (if I meter at f/8) and get good results?
     
  2. rst

    rst Member

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    You should also take into account long exposure reciprocity. Short: The longer your exposure time gets the less sensitive your film is. Depending on the exposure time that can be another few stops, especially with Foma 100.

    Here is an interesting read about Reciprocity failure: Click!

    Cheers
    Ruediger
     
  3. perminna

    perminna Member

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    Okay, thank you Ruediger!


    Which films you guys recommend to be used with pinhole cameras? I've been thinking of T-Max 100 in addition to FP4+ and Fomapan 100. In color I've been using for example Fuji Reala 100 and Kodak Portra 160VC with 120 (and 135) cameras. Do these all work (if the reciprocity failure is compensated with extended exposure time)? How about a slower film, like Rollei Pan 25?

    /Minna
     
    Last edited by a moderator: Jul 7, 2010
  4. xxloverxx

    xxloverxx Member

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    That would make your exposure time go into multiple hours — if that's what you're looking for, go for it.
     
  5. perminna

    perminna Member

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    Um, that's not what I want for now. I don't have the patience to take a long exposure like that.

    Let me get my math straight. If I use sunny 16 rule on a sunny day, I'd get f/16 and 1/125s with ISO100 film. f/16 is 7.5 stops away from f/207 which would convert exposure time to (roughly) 2 seconds. And taking reciprocity failure into account, the correct exposure would be 8 or maybe 16 seconds (2 or 3 stops). On a cloudy day exposure time would be 16 or 32 seconds. You need to use 30 min exposure times during night time, right? That would give about 2 h exposure time with ISO25 film.

    I think I start googling example pictures with proper descriptions.
     
  6. rst

    rst Member

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    You do not have that much of reciprocity failure for times around 2 seconds. So even with Foma 100 that only ends in the 5 seconds range.

    Using times which already have reciprocity correction and then go to a different film speed does not help. You have to change the measured time and then do reciprocity correction. Reciprocity correction is not simply a factor which you multiply your measured time with.

    Example HP5:
    Your measured time is 1/2@f8 which translates into around 7 minutes for f207. Add reciprocity will leave you at around 40 minutes.

    Now take a film which is two stops slower and assume it has the same reciprocity behavior as HP5:

    Now your measured time is 2 seconds @ f8 which translates into 28 minutes @ f207 and with reciprocity you end at around 5 hours and 30 minutes. Which is different from the 2 hours you would get if you calculate for the slower speed and start from the already corrected time of 40 minutes.

    And then there is the fact, that different films have different reciprocity behavior.

    Just to have a fun start I would recommend Fuji Neopan Acros which has nearly no reciprocity failure up to 120 seconds. And up to 1 hour it is less than a stop.

    Cheers
    Ruediger
     
  7. edp

    edp Member

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    Acros 100 needs hardly any reciprocity corrections up to exposures of several minutes, which is just one reason why it's good for pinholes.
     
  8. bsdunek

    bsdunek Subscriber

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    Allow me to introduce you to Mr. Pinhole http://www.mrpinhole.com/index.php Go to the exposure guide and enter your f-stop.
    A quick reciprocity table is at http://oak.cats.ohiou.edu/~schneidw/darkroom/reciprocity_corrections.html
    I have searched out several articles on the web of exposure and reciprocity and have made my own charts which I keep in my camera bag. With a little adjusting I can hit the exposure most every time.
    If you use negative film (FP4, HP5, etc.) then you print just like any photo. Works great and is a lot of fun!
     
  9. Pinholemaster

    Pinholemaster Member

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    A Black Cat Exposure calculator is a handy tool to have when working with pinhole cameras. Makes adjusting your exposure time from what your meter tells you to the new time for your pinhole aperture a simple turn of a wheel.

    http://www.blackcatphotoproducts.com/
     
  10. SMBooth

    SMBooth Member

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    Download and run Pinhole Designer ( http://www.pinhole.cz/en/pinholedesigner/ ), has a neat exposure calculator where you can select film type and it will give exposure with reciprocity factored in.
    Fuji ACROS has no reciprocity up to around 2min even more so its a good B&W pinhole film.
     
  11. perminna

    perminna Member

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    Thanks guys for clearing up things for me! I'll take a look at the links you posted.

    I have a Mac so PinholeDesigner is out of the question.
     
  12. bvy

    bvy Subscriber

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    Reciprocity (or failure thereof) basically means that the nice and neat linear relationship between EV and exposure time breaks down after a certain point. Mathematically, I wonder what a graph looks like for a given film and f-stop. That is, if you were to plot points for all exposure values and did some sort of curve fitting, what sort of function would you end up with?
     
  13. rst

    rst Member

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    Click!

    Cheers
    Ruediger
     
  14. grahamp

    grahamp Subscriber

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    With a 6x12 format you won't be enlarging all that much, if at all, so you may as well use a faster film. The natural softness of a pinhole image will outweigh any grain issues. If you need long exposures, use slower film. I mostly use Delta 400 at EI 200 for my roll film pinholes.

    Graham
     
  15. John Koehrer

    John Koehrer Subscriber

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    I also just got into the pinhole stuff and have used HP5+ with OK results. I've just used some Acros w/o adjusting for reciprocity & it looks fine.
    There are several pinhole sites out there with lots of information. f295, pinhole resource & others. F295 has an active group like APUG.

    The aperture on my camera is f235 so I made a mark on my meter @ f64 & just increase the time by two stops rather than deal with multiple increases of time.
    I used f64 because my calculator dial ran out of time indicators.
     
  16. perminna

    perminna Member

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    I'm probably going to try faster films too. I have a few rolls of Fuji Neopan 400 which has a relatively fine grain.


    Yeah, there are lots of sites. I have still few days before my camera arrives so I'll google and do research during the weekend.
     
  17. DWThomas

    DWThomas Subscriber

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    In my pinhole forays, I found that fast films called for too short an exposure in bright outdoor scenes to time reliably with a human-powered shutter (a true digital shutter -- operated by thumb and forefinger :D). So I have gone toward the slower films to get exposures out towards 4 or 5 seconds with my gear. There has also been some suggestions that high reciprocity failure in some of the fast films actually results in longer exposures than some of the better behaved slower films like ACROS 100.
     
  18. grahamp

    grahamp Subscriber

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    Using Delta 400 at EI 200 gives me a shortest time of two seconds in N. California (37 deg N.) with a clear sky. Long enough for manual timing, short enough to keep reciprocity under control. But a lot depends on the shutter mechanism.

    Graham
     
  19. John Koehrer

    John Koehrer Subscriber

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    I've been fiddling with the idea of an electronically timed shutter activating a small solenoid. The difficulty seems to be availability to timers with short(1/30-1/2sec) ranges. I found one source that could provide custom timing in that range for about an extra $100 + the timer($50)
    The other thing is operating voltage every thing seems to be 9-12-24V
     
  20. DWThomas

    DWThomas Subscriber

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    In theory I have some background to put a Rube Goldberg thing together with a microcontroller chip for the timing that could probably run on 6 volts, but as long as I can get exposures out toward 3 or 4 seconds or more, I figure it's not worth the effort (and I'm a slothful retired guy :tongue: ).
     
  21. Joe VanCleave

    Joe VanCleave Member

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    Ignoring reciprocity (which you can pretty much do with Fuji Acros or using paper negatives in large format box cameras), a good formula for converting a light meter reading into an accurate exposure for pinhole cameras is as follows:

    1) First, make sure you know the ISO of the film or paper you're using.
    2) Set the ISO value into your light meter.
    3) Meter your scene and reference the exposure time for the largest f-stop that your meter will read.
    4) Use the following formula to convert the exposure time for your camera's f-stop value:

    (f/R)^2 x Tm = Tc

    f=Your camera's f-stop
    R=the reference f-stop used on your light meter
    Tm= The uncorrected exposure time recommended by your light meter
    Tc= The corrected exposure time you'll actually use

    Example: The largest f-stop reading on my light meter is f/128. My camera's f-stop is f/280.
    Therefore: (280/128)^2 x Tm = Tc
    or: 4.785 x Tm = Tc
    So, whenever I use my f/280 pinhole camera, I reference the light meter's recommended exposure time for f/128 and multiply that value by 4.785 to arrive at the actual working exposure time. Once I do the complete formula once, I only have to know the multiplier factor and a simple multiplication (using my cell phone, or el-cheapo calculator that I carry with my camera) will give me the correct time. I can also make a chart to reference, rather than carrying a calculator.

    The only time I have to redo the entire formula to find a new factor is when I change the camera's pinhole size or focal length, or when I change light meters and the maximum f-stop reading is something different.

    Keep in mind when using this formula that the values for your Tm has to be in seconds, and the formula outputs the results in seconds. So, 1/8 second would actually be plugged in as 0.125, etc.

    I've found this method to be universally the best method, and works equally well for film as well as paper negatives.

    Again, the formula doesn't take into account reciprocity.

    ~Joe
     
    Last edited by a moderator: Jul 8, 2010
  22. perminna

    perminna Member

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    Thank you Joe! I'll give this a try when I get the camera. It was shipped on Wednesday from Poland so I'm expecting it to arrive to Finland around Tue/Wed next week.

    I love the math in photography. :---D
     
  23. perminna

    perminna Member

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    Thank you everyone for you advice. I got the Noon Pinhole camera last week and shot and deved a roll during the weekend. Here's one of the 6x12 shots I took on Kodak T-Max 100. I calculated exposure time based Joe VanCleave's formula (f/R)^2 x Tm = Tc. Because the exposure times were only around 4-5 seconds, I didn't add any time for reciprocity failure.

    The shot (click to view larger version):
    [​IMG]

    The camera:
    [​IMG]

    [​IMG]
     
  24. Joe VanCleave

    Joe VanCleave Member

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    That's a great looking image. I'm always amazed at the quality of good pinhole exposures onto medium format film.

    The forested trees in the foreground appear a bit dark, which is okay actually, but perhaps you might want a bit more detail present; this may have more to do with your metering method than reciprocity failure. You may want to try pointing your light meter at the trees and keep from getting too much sky exposure on the meter. I've come to do this when exposing paper negatives, since the sky gets blown out (i.e. over-exposed) using paper, I'm not interested in capturing detail in the sky, but rather the landscape itself, so I try and meter the foreground itself.

    I look forward to seeing more results; great job.

    ~Joe
     
  25. perminna

    perminna Member

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    I actually like the bright but not blown out sky and forest silhuette. But you're right, I should pay more attention to my metering next time!