18 Questions
What is the purpose of the flash bulb in photography?
To burn and emit a burst of light for photography
What is the purpose of emulsion in film or photographic paper?
To burn and give a photographic flash of intense light
What is meant by the term 'Ortho' in relation to film sensitivity?
Describes the responsiveness of wavelengths the emulsion supports
What type of film is sensitive to U.V. light up to green?
Infra-red film
How does a flash bulb generate light in photography?
By igniting an explosive primer when current flows through the filament
What is the purpose of Panchromatic film?
To capture images sensitive to all colors of visible light
What is the purpose of an Anti Halation Backing in a Blue-sensitive film?
To prevent light from bouncing back within the film
In terms of exposure time, what advantage does Panchromatic film offer under average lighting conditions?
It permits shorter exposures
What does the International Standard express as a combination for High film Speed?
ISO and DIN rating
Which type of Photographic Paper is more sensitive based on the American Association Standards?
Silver Chloride paper
What does the sensitivity of a film to light depend on?
The emulsion used in the film
Which type of film was originally designed for photographing objects under adverse lighting conditions?
Infra-red Film
What is the purpose of the stop bath in the photographic development process?
To neutralize the developer and prevent further development
Which chemical is used as the fixer in the photographic development process?
Sodium thiosulfate (hypo)
What is the purpose of dodging in the photographic printing process?
To selectively darken or lighten areas of the print
What is the function of the developing agent in the photographic developer?
To reduce the exposed silver halides to metallic silver
What is the purpose of vignetting in photography?
To selectively darken the edges of the image
Which of the following chemicals is used as a preservative in photographic processing?
Sodium bicarbonate
Study Notes
Flash Bulb
- A flash bulb is a chemical lamp that can be used only once.
- It consists of a metal filament in oxygen, which generates light when electrically contacted.
- The bulb is busted when fired, and the emulsion is coated on a transparent support inside the bulb.
Sensitized Material
- Emulsion is the part of the film or paper that contains silver grains, which are sensitive to light.
- Emulsion can be composed of three layers: Infra-red film, Orthochromatic film, and Panchromatic film.
- Spectral sensitivity is the responsiveness of the emulsion to different wavelengths of light.
Types of Films
- Orthochromatic film is sensitive to U.V. light up to green.
- Panchromatic film is sensitive to U.V. light up to red (all colors of visible light).
- Colored film can be divided into two types: reversal type and negative type.
Film Structure
- The base of the film is designed to hold back the light and prevent it from passing through.
- Anti-halation backing is used to prevent halation.
- Grain structure is a characteristic of Panchromatic film.
Photographic Paper
- Photographic paper is a sensitized material that records the visible image.
- Types of photographic papers include:
- Silver Chloride paper (used for contact printing)
- Papers with different emulsion sensitivities (e.g., Panchromatic, Orthochromatic)
Development Process
- Development is the process necessary to form the image.
- It involves the use of developing agents (e.g., D-76, Dektol), followed by fixation and washing.
- Other chemicals used in the development process include:
- Acetic acid (to prevent contamination)
- Sodium bicarbonate and borax (as accelerators)
- Potassium Bromide (as a neutralizer)
- Sodium Sulfate (as a preservative)
- Elon, Hydroquinone (as reducing agents)
- Acetic acid and Boric acid (to reduce silver halides)
- Sodium Thiosulfate (hypo) (as a fixer)
Printing and Enlarging
- Cropping is the process of omitting an object during printing.
- Dodging is a technique used to make adjustments during printing.
- Vignetting is the gradual fading of the image towards the sides.
- Dye toning is a process used to enhance the photograph.
Explore facts about flash bulbs used in photography, including their chemical composition and working mechanism. Learn about the role of metal halides suspended in gelatin and the process of generating light through rapid contacts.
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