With any color film making long exposures you have reciprocity effect. What that means is that as the exposure lengthens the film becomes less sensitive to light and you have to compensate for it. Each film has a different reciprocity value and you need to check with teh manufacturer. The problem is that you are faced with a law of diminishing returns. The longer the exposure, the more time you add to the exposure which adds to reciprocity failure. Kinda catch 22.Originally Posted by fuzzy
But, it depends on what you mean by "long exposure". If you mean a second, maybe 5 second exposure, add an extra stop ( for slide subtract a stop. bracket till you have a feel for your camera film combo. if you are talking about 30 sec, 1 minute or more then you have to do the math. I routinely shoot 1/2 to 8 second times and don't change the exposure.
Of course you can always shoot B&W and colorize it in PS http://forums.clubsnap.org/newreply....ply&p=1083998#