[pure-silver] Re: Pre-Exposure of Negatives

I've been doing this for years. But I use a piece of white frosted acetate. I mounted it in a filter holder so it is easy to put on the lens. After setting up for a photograph, if it is suddenly discovered that the light ratio is much too high, I put the diffusion filter over the lens, take a reading (TTL), reduce the exposure by three to four stops (you learn over time where to set it) and make an exposure. Then you remove the diffuser and take the real photograph on the same frame of film. This is valid for both color and B&W. I have used it extensively for color transparency work.

What it does is starts the exposure process without actually creating an image. There is an exposure inertia level that has to be started and this does it. This is what reciprocity is. This is why with long exposures, you typically have to double long exposures to get a correct exposure. Your meter may say 30 seconds but 60 seconds would be the correct exposure. The first 30 seconds simply overcomes the film's exposure inertia, the second 30 seconds is the real exposure. So pre-exposing at zone I-II with a diffuser, simply overcomes the films inertia in the shadows where there would not normally be enough exposure to make the silver halide react. It just adds a base density that helps in the shadows and does not hurt the highlights.

This is real easy with a 205FCC in the Zone mode...  :-)

Jim


At 04:30 PM 7/17/2006 -0700, Frank Filippone wrote:

You pre-expose by using a standard 18% grey card for 4 stops less than Zone 5. Then go ahead and take your real picture using the
metereing results you get from the scene..... do not use the grey card readings blindly. . He did it using a LF camera, and the
pre-esposure was done immediately preceding the real exposure.

Results are pretty hard to guess at, but it is a save the image time technique. It raises the Zone 1-4 without affecting the Zone
5+ tines.... It opens up the shadow areas. 

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