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Westminster Bridge
This is the first of a series of experiments I have been doing with my Zero Imaging pinhole camera shooting at night. Here I used Ilford Delta 3200 film but took my light meter readings at ISO1600. (I had to guess the reciprocity failure as I had forgotten to take my notebook with me in which I keep my reciprocity charts). Using a pinhole camera at night is tricky as the fixed aperture of the pinhole is f138 giving long exposures even in daylight. Add to this the reciprocity failure of film (this is the way the light sensitive crystals on the film gradually become less sensitive to light the longer they are exposed to light. So the longer the exposure on film, the more exposure length you have to add over and above what your light meter is telling you to account for this drop off in sensitivity. The very long exposures with pinhole cameras at night make the resulting exposures very long).
As I had forgotten my notebook I haven't recorded the exact length of this exposure but, from memory, it was around 30 to 45 minutes. There was a little residual twilight in the sky at the beginning of the exposure but by the end the sky was completely black, although in a city you always have the city lights providing illumination too).
When exposures on film become this long you don't have to worry about being too precise about exposure length. If the 'correct' exposure is 30 minutes and you expose for 45 minutes, you are only adding on half a stop. (less actually, if you factor in reciprocity).
Westminster Bridge
This is the first of a series of experiments I have been doing with my Zero Imaging pinhole camera shooting at night. Here I used Ilford Delta 3200 film but took my light meter readings at ISO1600. (I had to guess the reciprocity failure as I had forgotten to take my notebook with me in which I keep my reciprocity charts). Using a pinhole camera at night is tricky as the fixed aperture of the pinhole is f138 giving long exposures even in daylight. Add to this the reciprocity failure of film (this is the way the light sensitive crystals on the film gradually become less sensitive to light the longer they are exposed to light. So the longer the exposure on film, the more exposure length you have to add over and above what your light meter is telling you to account for this drop off in sensitivity. The very long exposures with pinhole cameras at night make the resulting exposures very long).
As I had forgotten my notebook I haven't recorded the exact length of this exposure but, from memory, it was around 30 to 45 minutes. There was a little residual twilight in the sky at the beginning of the exposure but by the end the sky was completely black, although in a city you always have the city lights providing illumination too).
When exposures on film become this long you don't have to worry about being too precise about exposure length. If the 'correct' exposure is 30 minutes and you expose for 45 minutes, you are only adding on half a stop. (less actually, if you factor in reciprocity).