Photography And Light

Question 1

What is “Stokes Shift”?

Answer 1

It is the difference between the peak of “Absorption” and the peak of “Emission” during the excitation process. This can be measured in energy, wavelength or frequency.

(Invented by Irish Physicist, George Gabriel Stokes)

Question 2

What is the, “Inverse Square Law”?

Answer 2

It describes how light loses power over distance.

If you double the distance between the light and the object, you will need four times as much light to get the same exposure.*

Question 3

What does DPI and PPI refer to?

Answer 3

DPI - Dots Per Inch (output device such as a printer)

PPI - Pixels Per Inch (input device such as a camera or scanner)

Question 4

What does the abbreviation, “Pixel” stand for?

Answer 4

Picture Element

Question 5

What three properties do pixels have?

Answer 5

• size
• colour value
• location

Question 6

What is a, “Pixel”?

Answer 6

• it is the basic building block of a digital image

Question 7

Does a digital camera sensor record in colour?

Answer 7

No, it can only record in grey scale.

Question 8

How does a digital camera capture an image?

Answer 8

Reflected light is captured by the light sensitive computer chip inside the camera. The image is then converted into a digital image by way of photoelectric conversion, which can then be saved as a JPEG, RAW, TIFF, etc.

Question 9

What are two types of light sensitive computer chips inside a digital camera?

Answer 9

CCD (Charged Coupled Device)
- commonly used in point-and-shoot cameras
- more expensive
CMOS (Complimentary Metal Oxide Semi-Conductor)
- used in Nikon DSLR camera
- cheaper than CCD

Question 10

What does, “FX” and “DX” refer to in relation to DSLR cameras?

Answer 10

FX - full frame, larger sensor (Nikon D800)

DX - cropped frame, smaller sensor (Nikon D300s)

Question 11

What is the purpose of a lens?

Answer 11

• it gathers light reflected from an object and brings it into sharp focus on the camera’s light sensitive sensor
• also dictates the angle of view

Question 12

What three things affect the exposure of an image?

Answer 12

• Aperture
• ISO
• Shutter Speed

Question 13

What is, “depth of field”?

Answer 13

• the zone of acceptable sharpness directly in front and behind the subject

Question 14

In what four (4) ways can you increase your depth of field?

Answer 14

• smaller aperture
• move further away from subject
• use shorter focal length lens
• focus on the “hyper focal point”

Question 15

What is meant by, “resolution” in a digital image?

Answer 15

• it refers to the number of pixels in an image

- the greater the number of pixels, the higher the resolution