Photographers Tony & Chelsea Northrup made this educational and tongue-in-cheek 5-minute video in which they rant about how many of the most common terms in photography are “stupid” because they’re often inherited from history (and therefore may not make sense immediately without digging deeper into each concept).
Here are the terms the Northrups’ run through in this video (which then turns into something of an infomercial):
The word “stops” dates back to 1858 and is based on a logarithmic scale, which can be difficult for people to understand.
Lenses can be fast and let in more light, or film can be fast with a higher ISO speed. But if a shutter speed is fast, it means less light reaches the sensor.
3. Shutter Speed
When people say “raise your shutter speed,” they actually mean to make the exposure shorter.
Named after the International Organization for Standardization, ISO is actually an acronym. The organization is there to standardize products and services across a number of different industries around the world. But since the name would have different translations in different countries, they settled on ‘ISO’ as an international standard instead of ‘IOS’.
5. Focal Length
Focal length is “equal to the distance between the image plane and a pinhole that images distant objects the same size as the lens in question.” In millimeters.
In a similar theme to shutter speed, raising an f-stop number makes the aperture hole smaller and lets in less light. F-stop originates from the late 19th century when it was first known as the “apertal ratio”.
7. Exposure Triangle
Tony personally doesn’t like the exposure triangle on the basis that it doesn’t actually include light, which photographers can add into the mix.
8. Depth of Field
Finally, the depth of field is a “fancy” word that should just be called “depth of sharpness,” according to Chelsea. It describes the area of a scene which is in focus (or “acceptably sharp”) and is sometimes referred to as “focus range” or “effective focus range.”