Field Of View Of Different Focal Length (mm) Lenses

 

 

Crop Factor Examples

 

Most digital camera sensors are smaller than film, so any image you see from those cameras is created from a smaller area than film.

If a photo is made with the same lens, but a smaller sensor, it shows a smaller area.

This is why it’s called a crop factor. The smaller sensor is cropping the lens’ image compared to a 35mm film frame. Ditto for what you see through the viewfinder.

35mm Film or Full Frame Sensor marked with digital camera sensor sizes. (Green: Canon 1.3x, Red: Nikon DX 1.5x, Blue: Canon 1.6x. Nikon FX Full Frame sensor and Canon Full-Frame sensor are the same size as the image in the film.) 

Image from 35mm film or full-frame digital SLR camera.

Image from a 1.3x sensor camera (Canon 1D series digital SLRs).

Image from an APS-C 1.5x sensor camera (Nikon DX digital SLRs).

Image from an APS-C 1.6x sensor camera (Canon digital SLRs).

 

Doing The Math

 

Crop Factor and Lens Focal Length

 

Multiply The Crop Factor Of Small Sensor By The Focal Length (mm) Of The Lens = The Full Frame Sensor Focal Length (mm) Of The Lens Equivalent

Example: Small Sensor 1.6 X 50mm = 80mm Full Frame Sensor Focal Length

Or, to write it another way:

Example: Full Frame Sensor 80mm / 1.6 = X 50mm Small Sensor Focal length

 

Crop Factor and Aperture

 

Multiply The Crop Factor Of Small Sensor By The Aperture = The Full Frame Sensor Aperture Equivalent

Example: Small Sensor 1.6 X f/2 = f/3.2 Full Frame Sensor Aperture

Or, to write it another way:

Example: Full Frame Sensor f/3.2 / 1.6 = f/2 Small Sensor Aperture

 

Crop Factor and ISO

 

You can also use crop factor to estimate the total image noise different sensors will have at a specific ISO. Simply multiply the ISO of the smaller sensor by the crop factor twice:

Multiply The Small Sensor ISO X (Crop Factor)² = The Full Frame ISO Equivalent

Example: Small Sensor ISO 100 X (1.6 X 1.6) = 256 Full Frame Sensor ISO

Or, to write it another way:

Example: Large Sensor ISO 256 / (1.6 X 1.6) = 100 Small Sensor ISO