|
While
the film responds with a doubling or halving of exposure in a consistent
and predictable way that allows us to control the density of the exposed
and developed negative, this consistency is only within certain bounds.
For instance at very high exposures over 1/4000 second or at exposures
longer than 1/2 or 1 second, most films do not react in the way we
would expect them to. They need more exposure to create a density
we would normally associate with 1 stop. This is called Reciprocity
effect or Reciprocity failure, and we need to calculate how much more
exposure is needed to correct for this.
General
charts can be used that give a rough guide for all situations.
Specific information can
be obtained from the manufacturer that give more detailed information
Reciprocity
effect for Agfa Ultra 50 ISO film
Exposure
reading |
1/10,000
to 1/2 second |
1sec |
10sec |
100
sec |
Exposure
adjustment
in f stops |
None |
+1/2
stop |
+
2 stops |
+3
stops |
Reciprocity
effect for Agfa Portrait 160 ISO film
Exposure
reading |
1/10,000
to 1/2 second |
1sec |
10sec |
100
sec |
Exposure
adjustment
in f stops |
None |
+1/2
stop |
+
2 stops |
+3
stops |
While the film responds with a doubling or halving of exposure in a
consistent and predictable way that allows us to control the density
of the exposed and developed negative, this consistency is only within
certain bounds. For instance at very high exposures over 1/4000 second
or at exposures longer than 1/2 or 1 second, most films do not react
in the way we would expect them to. They need more exposure to create
a density we would normally associate with 1 stop. This is called Reciprocity
effect or Reciprocity failure, and we need to calculate how much more
exposure is needed to correct for this.
General
charts can be used that give a rough guide for all situations.
Specific information can be
obtained from the manufacturer that give more detailed information
Reciprocity
effect for Agfa Ultra 50 ISO film
Exposure
reading |
1/10,000
to 1/2 second |
1sec |
10sec |
100
sec |
Exposure
adjustment
in f stops |
None |
+1/2
stop |
+
2 stops |
+3
stops |
Reciprocity
effect for Agfa Portrait 160 ISO film
Exposure
reading |
1/10,000
to 1/2 second |
1sec |
10sec |
100
sec |
Exposure
adjustment
in f stops |
None |
+1/2
stop |
+
2 stops |
+3
stops |
|
