# Difference between EV and f/stop

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##### New Member
Hi guys,

I've read up on EV and f/stop but still unclear about the difference between them. Say if i'm using f/16 with a shutterspeed of 1/30 and a guy tells me to -1 EV and 2nd guy says -1 stop down, what does it implements?

Thanks alot

#### flowerpot

##### Senior Member
Hi guys,

I've read up on EV and f/stop but still unclear about the difference between them. Say if i'm using f/16 with a shutterspeed of 1/30 and a guy tells me to -1 EV and 2nd guy says -1 stop down, what does it implements?

Thanks alot
-1 EV is 1 stop down, they are the same...or increase factor of 1.4 or half the shutter speed or half the ISO...

+1EV is vice vise...

for ur case, mean either use f/22 or, use 1/60, either 1 will reduce -1EV which also means reduce the light by half...

A good way to understand
http://www.dpreview.com/learn/?/Glossary/Exposure/Exposure_01.htm

#### alternatve

##### Senior Member
Hi guys,

I've read up on EV and f/stop but still unclear about the difference between them. Say if i'm using f/16 with a shutterspeed of 1/30 and a guy tells me to -1 EV and 2nd guy says -1 stop down, what does it implements?

Thanks alot
EV refers to Exposure Value, a formula including the shutter speed and aperture pertaining to the reading taken from a meter. Thus, 1/30 f/16 is the same EV as 1/15 f/11 or 1/60 f/22. An f/stop refers to the different openings of the aperture, ie f/1.4, f/2, f/3.5, f/4 and beyond.

Also, -1 EV means either turning up the shutter speed a notch (faster speed = lesser light) or closing the aperture a notch (smaller hole = less light), not both! Vice versa if you wish to +1 to EV.

But in Av and Tv mode, you can simply adjust the EV compensation to a maximum of -2 to +2 EV in either 1/3 or 1/2 stops, making the process a lot easier.

Samuel

#### aq12345

##### New Member
Basically, 1 stop = 1 unit of light, so lets say, 2 stops higher, means an increment of 2 units of light
Assume there are 2 settings, 1/500 f/2.8 and 1/250 f/2.8, 1/250 with an aperture of 2.8 would mean double the amount of light entering the light, so that's 1 stop difference.

And btw, to calculate stops, the difference of stops of the aperture is calculated in Root 2

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