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Photography Question 

Carissa Knapp
 

purposely exposing film


Hi. I am trying to purposely expose a roll of film. To get the best random colors, etc. should I open up the film to light in the beginning, middle or end of shooting the roll? Thanks!!


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March 09, 2008

 

Alan N. Marcus
  Hi Carissa,

Your question seems strange however; I know there are no norms when it comes to art so here goes.

Unexposed film requires light or other radiant energies to cause the sensitized silver salt crystals to become exposed and thus rendered developable. Each silver salt thus has a threshold requirement. In the camera, light from the scene streams through the camera’s optical system and bathes the film with light energy in proportion to the brightness distribution.

Should you pre-expose the film to light, and the light level (energy) you supply is below exposure threshold, then the film will be made more sensitive to light. You can do this uniformly or perhaps fabricate a way to add this exposure randomly as to both color and intensity. In any event those locations that receive this exposure will be artificially elevated as to ISO. This is known as hyper sensitization. It is a valid technique used to increase film’s sensitivity to light. Hyper sensitization is normally preformed via a uniform light exposure or exposure to chemical fumes prior to the camera exposure.

You can flash after the camera exposure. In graphic arts, a flash exposure is used to change the film’s characteristics. A bump exposure is a flash with the halftone screen removed; this is just another way to alter the film’s scale.

You can have lots of fun pre-exposing and post-exposing. You must figure out how to control these exposures, and you can use different color flashes. You are mostly on your own as this will be your experimentation. I envy you – go to it.

Alan Marcus
ammarcus@earthlink.net


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March 09, 2008

 

Alan N. Marcus
  Last night an idea hit me. No it wasn’t the wife or the dog; it was just a pure notion. Seems from your description you want to capture odd and strange colors and shapes by exposing film to non-imaging light bursts.

You might want to use the web to check out shadowgraphs. This is a method whereby objects like leaves and keys and watches or maybe lace are placed (in the dark) on top of film and then briefly exposed by turning on the lights or using odd light sources like sparks and the like. I was thinking you might try the new LED toys, you know the ones that have red – green – blue – spinning LEDs. Look at the works of William Henry Fox Talbot who did this in 1836. You could use sparking toys or use your imagination regarding other light sources. Maybe you would be better using an old junk 120 box camera, the film is bigger.

Alan Marcus


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March 10, 2008

 

Christopher A. Walrath
  If you camera has a multiple exposure setting you might try making a random exposure with each individual frame before making your image? Just a thought.

Thank you
Chris


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March 10, 2008

 

Carissa Knapp
  Thank you so so much for all the help. I am so impressed with the answers and how helpful you all have been! Will let you know!! Thank you again.


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March 10, 2008

 
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