Sensitometry Flashcards
2 scientist introduced sensitometry
Hurter
Driffield
Science of evaluating the perfomance of photographic materials
Sensitometry
Requires photographic emulsion be exposed to specified light source
Sensitometry
Plot of the density vs. amount of exposure
Characteristic curve
Characteristic curve is also called
Sensitometric curve
H&D curve
D log E curve
Exposure is plotted on
X-axis
Density is plotted on
Y-axis
Curves always assumes some form of
S or Sigmoid shape
Basis of sensitometry
Density
Density has a log value of
0-4
Density of 1
10% light transmission
Density of 2
1% light transmission
Density of 3
0.01% light transmission
Shaped like a step wedge to produced an exact and regular increase or decrease in exposure
Aluminum step-wedge / penetrometer
Prints a pre-exposed negative directly onto the film
Sensitometer
Measures the optical density of a portion of an image using a 0-4 scale
Densitometer
The recorded density of the base and recorded density of the chemical fog
Basic fog
Absorbed longer exposed of film
Blue tint
Basic fog value should not exceed
0.25
Ponit where the film shows a reaction to expose
Threshold
Area rapidly increasing density
Toe
Carries a very large amount of information
Straight line portion
Straight line portion parts
True gamma
Average gradient
Latitude
Speed
Where first reaction to exposure begins to falls off
Shoulder
Max density which can be reached on the film
Max density
Caused by the silver halide grain not being absorbed
Region solarization
Equal to the slope of the straight line portion
Gamma
True value of average contrast available on the film
Average gradient
Useful exposure range of the film
Latitude
Range of exposure value drawn from the intercepts of 2 net densities
Latitude
Latitude is linked to the
Average gradient
Defined by ANST, exposure required to produce a net densities
Speed
Means that one film os 100% higher in speed than other (separation of log)
0.3
