Rule of Thumb: Difference between revisions

Revision as of 15:24, 31 December 2020

Some simple rules

The Sunny f/16 rule says:

On a sunny day, with ISO 100, you expose at 1/100s with aperture f/16

The minimum exposure time for a lens with focal length N mm is 1/N s. So minimum exposure time for a 50mm lens is 1/50s
For every doubling of the aperture, you need to quadruple the exposure time for the same light condition. So if you are exposing 1/200s with f/2.8, you need 1/50s with f/5.6 to get an image that is similarly bright.
The minimum focus distance of a regular lens is around 10x its focal length. So a 200mm lens focuses starting at 2meters. Macro lenses are obviously not like that.

These pages are for Amateur Photographers and not really for seasoned photographers and professionals. I have no affiliation or commercial interest with any brand/make. I write from my own experience. I ended up using mainly Nikon, so I am more familiar with this brand than others. See price for notes on pricing as well as photography related links.

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 * The minimum [[exposure time]] for a lens with [[focal length]] '''N''' mm is 1/'''N''' s. So minimum [[exposure time]] for a 50mm lens is 1/50s
 * For every doubling of the [[aperture]], you need to quadruple the [[exposure time]] for the same light condition. So if you are exposing <kbd>1/200s</kbd> with <kbd>f/2.8</kbd>, you need <kbd>1/50s</kbd> with <kbd>f/5.6</kbd> to get an image that is similarly bright.
+* The [[minimum focus distance]] of a regular [[lens]] is around 10x its [[focal length]]. So a 200mm lens focuses starting at 2meters. [[Macro]] lenses are obviously not like that.
 [[Category:rant]]
 {{Photodisclaimer}}