Photography Flashcards
Explain depth of field
Depth of field in photography is the range of sharpness in an image, controlled by the camera’s aperture.
A wide aperture (small f-number) = shallow depth, isolating the subject,
A narrow aperture (large f-number) expands the depth, keeping more of the scene in focus for a balanced or detailed composition.
Explain what the aperture does
Aperture in photography refers to the lens opening through which light enters the camera. Measured in f-stops (e.g., f/2.8), it affects depth of field and exposure. Wider apertures (lower f-numbers) create a shallow depth of field, while narrower apertures (higher f-numbers) increase depth of field, impacting image focus and light intake.
https://visualeducation.com/photography-course/aperture-depth-of-field/
What is focal lenght
a. the distance to the subject
b. the distance either side of the subject which is optically clear
c. the length of the film
d. the distance light travels from the front of the optics to the film plane
Answer: the distance light travels from the front of the optics to the film plane
Colours will disappear as light travels through seawater because of?
Absorption
What will increase the depth of field?
Increase the f number
Smaller aperture (larger f-number) increases the depth of field in photography, keeping more of the scene in focus.
What will increase the field of view of a lens?
A short focal length
What is the main advantage of photography over CCTV?
It gives a very high resolution
What best describes photogrammetry?
Stereo photography with computer assessment
What is meant by bracketing the exposure during photography?
Taking 3 pictures varying the exposure to ensure the correct result
If there is a need to increase the depth of field, what should be done?
Increase the F number
When using close up prods for an NDT inspection which of the following should be done?
All of these
- Bisect the angle between the components
- Include a scale
- Ensure the inspection is properly lit
Which of the following best describes film speed
a. The speed with which the film can be advanced
b. the length of time a film is exposed
c. a numerical value relating to the sensitivity of the film
d. none of the above
Answer: a numerical value relating to the sensitivity of the film
What is backscatter?
Light reflected back from suspended particles in the water
What is the photosensitive part of a colour negative photographic emulsion?
Silver halide crystals
A high ISO number on a digital camera signifies?
A fast reaction to light
Macro photography is
Taking close-up photographs
Focal length ratio factor is defined as?
Focal length divided by the aperture
Which of the following is a definition of depth of field with regards to under water photography?
The distance in front of and behind the subject that is in acceptable focus
What does the ISO number on a digital camera signify?
How quickly the camera electronics will react to the light.
A badly positioned flash may cause
Illumination of suspended particles, possibly causing back scatter
Why does the f-stop number get smaller when the aperture gets bigger.
The f-stop number is determined by the ratio of the focal length of the lens to the diameter of the aperture. The formula for calculating the f-stop is:
f-stop= focal length /
aperture diameter
As the aperture diameter increases, the f-stop number gets smaller. This is because the f-stop is essentially a fraction, and as the denominator (aperture diameter) increases, the whole fraction becomes smaller.
For example, if you have a lens with a focal length of 50mm and an aperture diameter of 25mm:
f-stop = 50 / 25
f-stop is 2, indicating a relatively large aperture.
https://visualeducation.com/photography-course/aperture-depth-of-field/
Think of the f-stop number as a fraction. It represents the ratio of the focal length of the lens to the diameter of the aperture opening. When the aperture gets bigger, the denominator of this fraction (the diameter of the aperture) gets larger.
Now, when you divide the same focal length by a larger number (the diameter of the aperture), the result is a smaller fraction. And since the f-stop number is the inverse of this fraction, it gets smaller as the aperture gets bigger.
So, when you see a smaller f-stop number, it means the aperture is larger, allowing more light to enter the camera. This is useful in low light conditions or when you want to achieve a shallower depth of field in your photographs.
