----- Original Message ----- From: "Mark Interrante" <[email protected]>
>Ok, I've a question. I recently saw Martha Casanave's Lenin photos >(http://marthacasanave.com/lenin.html) >and I think they are beautiful. She uses a non-optimial pinhole, and I'd >like to know if people have any idea how much larger I would need to make >a pinhole to achieve this effect? I missed this post, here is a somewhat late suggestion: Eric Renner's book has a set of pinhole images of the same subject (I believe it is the portrait of a nun or a nun looking girl), each image was made with a differente size of pinhole and if memory serves me well the f/stop is shown for each image, if that is so, just take a a look at the different images, select the one that best represent the effect you want and find how mant stops there are between the sharpest one and your selection, That would be the number of stops your pinhole should be larger than the optimum, in order to get a similar effect. i.e.: your selection is f/128 and the sharpest is f/320, that gives you almost 3 stops between 128 and 320 (128, 180, 256, 360), so the pinhole you want should give you an f/stop 3 stops bigger than the optimum. The above is just a good starting point as there are some othe factors to take into account. A more hands-on approach would be to make a series of pinholes giving 1 stop, 2 , 3, 4, 5 stops and so on, larger than the optimum. That is easily achieved by multiplying the optimum diameter by the f/stop sequence starting with 1.4 so the sequence goes 1.4 - 2 - 2.8 - 4 - 5.6 - 8 - etc., then make exposures of the same scene, using all of the pinholes, develop the film, print the images to the size you'd normally be enlarging the negatives and then select which one is the ONE for you. After the test you should know how many stops larger should the pinhole be, that info could be applicable for other pinhole focal length. An example would be: Camera = your SLR Focal length = 50mm optimal pinhole = 0.010" series of pinholes: (0.010 x 1.4) = 0.014" (1 stop larger that optimum) (0.010 x 2 ) = 0.020" (2 stops larger) (0.010 x 2.8 ) = 0.028" ( 3 stops larger) (0.010 x 4 ) = 0.040" (4 stops larger) Anyway, you get the idea. Guillermo
