I’ve probably discussed before the way that different size “sensors” (or pieces of film) need different focal length lenses to achieve the same angle of view. For instance, it is well known that a 50mm lens on an APS-C crop-sensor DSLR behaves a bit like a 75mm lens on a 35mm full-frame camera. I’ve extended the idea a bit further and represented various formats and various focal lengths in a graphical form[1].
Along the top are various formats[2], and down the left are focal lengths in millimetres. Each cell contains the diagonal field of view in degrees[3], and is colour-coded to show what kind of lens this represents.
It’s absolutely inconceivable that anyone could possibly improve on my incredibly awesome spreadsheet, but just in case you want have a play, you can grab the file here.
Notes
- Unlike Microsoft Excel, LibreOffice Calc doesn’t have a contour graph type, so I had to do the graphic this way. Anyone suggesting the use of Microsoft Office will have their teeth cut out 😉
- 10×8, 5×7 and 5×4 are large format and are measured in inches. All of the 6×9, 6×7, 6×6 and 6×4.5 formats are medium format and measured in centimetres. I probably should have indicated this in my column headings.
- Equation for angle of view:
where αd is the diagonal angle of view, d is the diagonal measurement of the sensor and f is the focal length of the lens.
Jonathan Gazeley 