Ex­po­sure

Bird Watching (UK) - - Part One -

It’s all about record­ing light, in or­der to cre­ate an im­age that isn’t too bright or too dark. Through the use of aper­ture, shut­ter speed and ISO, we can change how much light is recorded to pro­duce cor­rectly ex­posed im­ages. this is sim­ply the size of the hole in the lens that light passes through. Aper­ture is given in f-stops, with the smaller the num­ber in­di­cat­ing a larger hole for light to pass through. So an f2.8 aper­ture lets a lot of light in, f8 far less. Aper­ture also de­ter­mines depth of field. This is how much will be recorded in fo­cus – the smaller the num­ber, the less depth of field. So at 2.8 you are go­ing to get a min­i­mal amount in fo­cus, with the rest of the frame fall­ing into blur, while at f8 you will see far more de­tail through the frame. SHUT­TER SPEED – it does what is says on the tin. It’s the length of time it takes for the shut­ter to close and re­open. The faster the speed, the more the im­age freezes mo­tion, with slower speeds al­low­ing blur into an im­age. For bird pho­tog­ra­phy most im­ages you’ll want to shoot us­ing the sim­ple guide­line that your shut­ter speed should be at least that of the length of your lens, so if you have a 300mm lens, you will want at least a 1/320 of a sec­ond shut­ter speed to freeze the ac­tion and en­sure a sharp im­age. Aper­ture and shut­ter speed are linked. If you have a wide aper­ture of 2.8, you are let­ting in a large amount of light, thus the shut­ter speed can

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