Photography means ‘writing with light’ But writing needs control. In photography one of these controls is the combination of aperture and shutter speed: EV or "exposure value".
Historically a problem encountered by beginners is understanding apertures and shutter speeds. Manufacturers have come to your aid by evolving automated exposure controls; aperture priority, shutter priority, program, matrix, spot, multi segment + different names for the same function by different manufacturers. The cure is now more complex than the problem. Aperture/ shutter speeds - ½ and third stops. The concept of apertures and shutter speeds is fairly easy to understand. Let me draw a parallel: Buy a camera - cost £100, but you need to save up for it. £50/wk for 2wks £ 2/wk for 50wks £25/wk for 4wks £ 4/wk for 25wks or any combination in between. This is a combination of Quantity and Time: Quantity is aperture Time is shutter speed Let’s look at them individually and take the easier one first Shutter Speeds
You will make mistakes!! Let's say the ‘Correct exposure’ for a scene is 125th sec @ f8. 1 stop 60th @ f11 1 stop 250th @ f5.6 2 stops 500th @ f4 2 stops 30th @ f16 3 stops 1000th @ f2.8 3 stops 15th @ f22 All these combinations will give the same exposure - but not the same effect. ISO ratings Scale refers to sensitivity of CCD - the higher the number the quicker the response. Low number - 25 ISO slow High number - 800 ISO fast 100 200 400 800 etc. also doubles/halves. Higher number leads to grain/digital noise Definition - Exposure is the amount of light allowed to reach a CCD via a combination of aperture and shutter speed. Conclusion - Aperture and shutter speed is the way light is controlled to enable an exposure to be made. by Neil Blair Comments are closed.
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