Dark room

Question 1

Purpose of safelight?

Answer 1

Permit only passage of light frequencies to which the film is least sensitive
· So you can still see what you are doing in the darkroom

Question 2

Possible causes of darkroom fog?

Answer 2

· Unsafe safelights
· White light leak
· Excessive developer time, strength, or temperature

Question 3

Action of developer?

Answer 3

· Reduce exposed crystals on the film to black metallic silver

Question 4

Action of fixer?

Answer 4

· fixer stabilizes the image, removing the unexposed silver halide remaining on the film, leaving behind the reduced metallic silver that forms the image, making it insensitive to further action by light. Without fixing, the remaining silver halide would quickly darken and cause fogging of the image

Question 5

What is replenishment?

Answer 5

· New chemistry added to replace volume lost as a result of solution use
· Replenisher is stronger than original solution to compensate for lost strength in the solution that remains
· Decreased film volume requires increased replenishment rates
· Correct replenishment is critical to proper processing

Question 6

Components of film?

Answer 6

·         Photographic emulsion at each end (called dual emulsion)
o        Gelatin
o        Silver halide microcrystal’s
o        Silver bromide – 90%
o        Silver iodide – 10%
o        Silver sulfide (catalyst)
·         Polyester base in the center
·         Pattern of exposed and unexposed crystals on a film is called the latent image

Question 7

What is photosensitive?

Answer 7

· Silver halide crystals

Question 8

What are artifacts?

Answer 8

· defects in the x-ray film image due to faults in the cassette (screen artifact) or in the film (film artifact).
· a mark on x-ray film caused by discharge of static electricity.

Question 9

What are the steps in processing?

Answer 9

·         Load film on hanger
·         Immerse film in developer
·         Rinse
·         Immerse film in fixer
·         Wash
·         Final rinse
·         Dry
·         Be sure films are not touching to avoid artifact

Question 10

Function of the roller assembly?

Answer 10

· Part of the transport system for automatic processing. Move film through processor
· Roller action helps agitate solutions
· Squeegee action of final rollers in each rack removes excess chemicals

Question 11

What are the tools of Sensitometry and their functions?

Answer 11

· Sensitometer
o Exposed film in darkroom to create a gray scale
o Precisely controlled light source
· Densitometer
o Used to measure radiographic densities on sensitometric strip

Question 12

What are the 3 measurements taken in sensitometry?

Answer 12

· Speed index (+/- 0.15)
· Contrast index (+/- 0.15)
· Gross fog index (+/- 0.03)