In Part One of this series we went over the basics of lens aperture and how it effects and how to use it to control the amount of light that enters your camera. In part two we will go over the basics of ISO or Film Speed.
Film Speed
Film speed is a number that represents the film’s sensitively to light. The higher the number the more sensitive to light, in that less light is needed to take a well exposed photo. Film speeds range for 25 to 1600 and sometimes 3200. Some example uses are:
- 25 to 200 is best for portrait work
- 400 is best for mixed lighting settings (ex: outside and inside shots on same roll)
- 800 to 1200 is used for fast moving objects in mixed lighting.
- 1600 for very fast moving objects like a car race.
Higher speed films can be used creatively. For instance I shoot concerts with my camera set to 1600ISO and my aperture wide open (2.8 or faster usually) with my cameras AV setting.
The trade off of a faster film speed is increased graininess. The faster films have a more noticeable grain structure as the individual grains clump together to form spots that are visible to the naked eye. This is not as noticable in smaller sized prints as it is in enlargements and is mostly undesirable except in some black and white shots.
Note on Digital Cameras
ISO works relatively the same in digital cameras and is comparable to films rated at the same speeds but instead of grain the image will produce “noise”. Sometimes this can be enhanced by a larger megapixel camera due to the amount of pixels packed in to a sensor. If the sensor size of a 14 megapixel camera and a 12 megapixel camera are the same then the 14 megapixel camera will show more noise at a faster ISO since the 14 megapixel sensor’s individual pixels do not collect as much light.
Overall film speed is more straightforward and easiest to understand in the Photographic Triangle.
In part two we will cover shutter times.
*This is part of my series to introduce people to the world of photography. My hope is to help current DLSR camera owners to stop relying on the auto setting of their camera and unlocking the photographic potential of what they hold in their hand.
Richard Call is a Nashville, Tennessee based photographer whose work has been published locally as well as internationally and can be seen at richardcallphotography.com
Facebook | @rcphoto
Related posts:
- Photography 101 — The Photographic Triangle: Shutter Speed (3 of 4) In Part One and Two of this series we went...
- Photography 101 — The Photographic Triangle: Working Together (4 of 4) In the first three parts of this series we...
- Photography 101 — The Photographic Triangle: Aperture (1 of 4) As a photographer, understanding light is the most important and...
- Photography 101 — Sunny 16 Rule The sunny 16 rule is a good rule-of thumb to...