Categories: Basic Theory Photography
EV = Exposure Value
EV value is a combination of shutter speed and diaphragm, may also be said as the value of how light / dark photo.
EV number is the number for 1st time exposure (1 take 1 frame), does not apply to double / multiple exposure. More, EV is the result of calculation of speed, diaphragm, and ISO. Following formula:
EV = log 2 (aperture2 x (1/shutter speed) x (ISO sensitivity/100))
In photography, the EV is the amount of light needed for 1-time exposure, the rate of EV also represents the right blend between the diaphragm shutter speed to get a normal exposure, no less and no more. Here is a table with a note EV ISO 100:
So for example, you are in room A is speed 1 / 125 and diaphragm 5.6 and ISO 100. Mean value of EV is 12. And when you’re in the room you get a diaphragm B 4, then to get the EV value (large dark / light) the same, you should use a speed 1 / 250 Since the EV value 1 / 125 & 5.6 with 1 / 250 & 4 are the same.
On the camera feature, the difference we can set the EV suit, changing the EV difference in the camera with changing compensation compensation exposure.Beda one 1 / 2 or 1 / 3. On my camera, Canon PowerShot A70, in P mode, Av, and TV, EV can be set as the above items. When in Manual mode (M), the difference EV can be searched by combining the speed and the diaphragm.
The following are examples of different EV, each with different EV is 1 / 3. I make use M mode on the camera, combining speed and diaphragm for the EV different
No. 1: I took a 0.5-second speed with the diaphragm 2.8 (-1 / 3)
No. 2: I took a speed 0.8 seconds with a diaphragm 2.8 (0)
No. 3: I took a speed 1.0 seconds with a diaphragm 2.8 (+1 / 3)
Note: The picture was not edited, just cropping and resize in PS. Taken with ISO 100. Use of different EV can be adjusted to the needs.
Often we see the camera is writing the specifications (example): SLR Light Meter: EV 1-20 at ISO 100 and f/1.4 This means that if you use f1.4 lens with a diaphragm and an ISO 100 film, the camera makers to ensure the reading value 1 EV of the value of 20 will be accurate.
But if you use f/4.0 lens with a diaphragm, the camera light meter will read a different 3 stops, then the light meter readings will be accurate in the value of EV 4 23.
Note: by using a different lens then the description of a photograph will be different. But when using film with a different ISO, then the description of a photograph will be the same.
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