EV, F-stop and shutter speed relationship


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Climber

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#1
Hi all,
Recently i've been reading up and came to a conclusion that EV is just an overall control of F-stop and shutter speed. However i'm not convinced that i'm correct.
just to emphasize why i thought so is becoz when i adjust the shutter speed faster in my cam, the EV will start to move from left to right (or vice versa).
Ok my question is ... so what function does adjusting the EV of a camera do? (when adjusting the shutter speed or aperture will give you the same function) Anything to do with metering? :dunno:

Newbie question hope for all your advice.
Thankx :sweat: :sweat: :sweat:
 

theITguy

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#2
EV == Exposure Value?

Well, EV to me is like a value given to a uniform light source. But as you know, not every picture is taken with a uniform light source, some darker some brighter, therefore you have to compensate to go for the highlights or shadow. For me it is the highlights since I shoot slides (digital users too). Neg users normally go for the shadows (if you know how neg works). The higher the EV value the brighter the subject matter, hence a higher shutter speed or smaller aperture size to use.


Look at this table for some reference.
 

Climber

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theITguy said:
EV == Exposure Value?

Well, EV to me is like a value given to a uniform light source. But as you know, not every picture is taken with a uniform light source, some darker some brighter, therefore you have to compensate to go for the highlights or shadow. For me it is the highlights since I shoot slides (digital users too). Neg users normally go for the shadows (if you know how neg works). The higher the EV value the brighter the subject matter, hence a higher shutter speed or smaller aperture size to use.


Look at this table for some reference.
So are you saying that the EV range i see in the viewfinder is actually a reference for me to see how exposed the light source or anyobject i'm pointing is?

If you're telling me this then the (+/-) button that adjust EV is for what huh? since adjusting the shutter speed and aperture size can do the same job.
 

sulhan

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#4
APEX equation....Additive Photographic EXposure system (APEX)

Do a search on APEX equation on google and you can find some good read up....on the equation....

Its an equation relating these parameters....
T: Shutter time - shutter speed
EV: Exposure value
L: Scene luminance - brightness
ISO:Arithmetic ISO film speed
K:Calibration constant
A:Lens f-number


Its used by almost all camera makers to tabulate data for use in their cameras....


rgds,
sulhan
 

dkw

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#5
Climber said:
Hi all,
Recently i've been reading up and came to a conclusion that EV is just an overall control of F-stop and shutter speed. However i'm not convinced that i'm correct.
just to emphasize why i thought so is becoz when i adjust the shutter speed faster in my cam, the EV will start to move from left to right (or vice versa).
Ok my question is ... so what function does adjusting the EV of a camera do? (when adjusting the shutter speed or aperture will give you the same function) Anything to do with metering? :dunno:

Newbie question hope for all your advice.
Thankx :sweat: :sweat: :sweat:
Are you shooting shutter priority? Sometimes you can set an inappropriately fast shutter speed such that your lens aperture can no longer compensate. It that case, you EV value will fall as you dial up your shutter speed. The other possibility is that you are shooting in manual mode, during which the aperture is fixed as you change shutter speeds and the above applies again.

Cheers,
 

theITguy

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#6
Climber said:
So are you saying that the EV range i see in the viewfinder is actually a reference for me to see how exposed the light source or anyobject i'm pointing is?

If you're telling me this then the (+/-) button that adjust EV is for what huh? since adjusting the shutter speed and aperture size can do the same job.

That one is exposure compensation (EC), not EV. You need more readup here and there actually. I did not go through any formal training, just readup online so far, therefore my knowledge is limited. The best thing is to read your manual also, as they do teach you certain techniques or how to use your equipment properly.

Asking online sometimes not that useful, as response may be slow, but still a start to better techniques and understanding. ;)
 

Climber

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#7
Many thanks to sulhan, dkw and theITguy. Think i got confused with EC and EV. Guess I'll have to do more research next time ... sorry for this. and thanks for helping me clear up my doubts. Cheers!
 

user111

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loosely speking, EV is a spectrum of certain combinations of shutter speed and aperture
 

The_Cheat

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Hey Climber, if you're interested to know more regarding EV, we can meet up to have a cup of kopi. Think it's easier to show you what EV means on both the camera and lightmeter. Reading on terminologies could sometimes be very very confusing!
 

megaweb

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#10
Adjusting the EV = Exposure Compensate (EC)

in Av or A mode, you can adjust the EV by shutter speed
in Tv or S mode, you can adjust the EV by aperture value

What does it really do ?
When the metering fails to give the correct exposure due to certain scenarios

Example
A black panther is sitting on the grass in the zoo.

If u use spot meter on the black panther in Av or A mode, you will get very slow shutter (like taking night shots) and background will be overexposed. This exposure is not good. To give a better exposure, you need use EC and set to EV -1 to -2 by adjusting to faster shutter to to give better exposure.

Just my 2 cents worth
 

blurblock

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#11
Climber said:
Hi all,
Recently i've been reading up and came to a conclusion that EV is just an overall control of F-stop and shutter speed. However i'm not convinced that i'm correct.
just to emphasize why i thought so is becoz when i adjust the shutter speed faster in my cam, the EV will start to move from left to right (or vice versa).
Ok my question is ... so what function does adjusting the EV of a camera do? (when adjusting the shutter speed or aperture will give you the same function) Anything to do with metering? :dunno:

Newbie question hope for all your advice.
Thankx :sweat: :sweat: :sweat:
EV is just a product of F-stop and shutter .....

For example, if you adjust the shutter speed faster, and the F-stop remain constand, the exposure will be lesser.

If your EV is set to 0, and you are in aperture priorty mode, if you adjust the shutter speed to faster, the aperture will open bigger.

If your EV is set to 0, and you are in shutter priority mode, if you adjust the aperture to bigger, the shutter speed will be faster.

If your EV is set to 0, and you are in manual mode, if you adjust aperture to bigger by one stop or shutter speed to slower by one stop, you will see your EV setting turn to +1.

Understand?
 

sumball

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#12
blurblock said:
If your EV is set to 0, and you are in aperture priorty mode, if you adjust the shutter speed to faster, the aperture will open bigger.

If your EV is set to 0, and you are in shutter priority mode, if you adjust the aperture to bigger, the shutter speed will be faster.
If in aperture priorty mode, shouldn't we adjust the aperture and the camera will compesate the shutter speed for us vise versa for shutter priority mode?
If your EV is set to 0, and you are in manual mode, if you adjust aperture to bigger by one stop or shutter speed to slower by one stop, you will see your EV setting turn to +1.
Ain't we'll see +2 instead? Or your bigger aperture is referring to the figure change from f8 to f11 instead of the physical aperture change?:sweat:

Thanks.
 

blurblock

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#13
sumball said:
If in aperture priorty mode, shouldn't we adjust the aperture and the camera will compesate the shutter speed for us vise versa for shutter priority mode?

Ain't we'll see +2 instead? Or your bigger aperture is referring to the figure change from f8 to f11 instead of the physical aperture change?:sweat:

Thanks.
Opps, said the oppsite thing .... Paiseh :D ...

Aperture Priority = Adjusting the aperture so the shutter speed can shift to suit the aperture.

Shutter Priority = Adjusting the shutterspeed so the aperture can shift to suit the shutter :D...,, :embrass:
 

sumball

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yeah! I caught you! :sticktong
 

Climber

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#15
The_Cheat said:
Hey Climber, if you're interested to know more regarding EV, we can meet up to have a cup of kopi. Think it's easier to show you what EV means on both the camera and lightmeter. Reading on terminologies could sometimes be very very confusing!
Sure Adam. well ... now hoping for a next shoot to finish up my roll of film the last time. ( at marina ) Sianz... now doing portfolios to enter uni or laselle STRESSED arrgh. :hung:
 

Climber

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#16
blurblock said:
Opps, said the oppsite thing .... Paiseh :D ...

Aperture Priority = Adjusting the aperture so the shutter speed can shift to suit the aperture.

Shutter Priority = Adjusting the shutterspeed so the aperture can shift to suit the shutter :D...,, :embrass:
Sorry blurblock (no pun intended) i know what you're saying ... maybe my question is abit vague.
Let me rephrase. When i shoot in manual mode. When i point my spot meter, the EV bar pops up and will change constantly when i move about. At that point i thought ... ok this EV should be a thingy to MEASURE <--(take note of this word) the exposure value of the spot i'm pointing at. So i happy... i look at books and stuff then i realised.....

EH!!! if this thingy is used to measure the "correct exposure" of the thingy then this button --> (+/-) is used to change the exposure also wat. So if we change the "correct exposure" then what is EV in the camera? isit only a METER or isit a thingy that has the final say in shutter speed and aperture?

Now kinda think that it has double uses.
 

theITguy

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#17
The TTL (or more advanced E-TTL 2, 3D Matrix etc etc) meterings is to detect the EV value (by using spot or evaluative whatever), compensate it against the other part of the photo (for different metering modes only) and give a shutter speed and aperture value according to your ISO film speed used. A spot metering will give you the EV value of that point (1% of photo normally), the Evaluative metering on my EOS 33 lookout for the differences against other part of the photo and gives a shutter speed and aperture.
 

The_Cheat

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#18
Climber said:
Sure Adam. well ... now hoping for a next shoot to finish up my roll of film the last time. ( at marina ) Sianz... now doing portfolios to enter uni or laselle STRESSED arrgh. :hung:
Don't be too stressed up by your buddy witness lah. Play around with photography a bit more, get the feel of it, and slowly build up a representative portfolio.
 

Witness

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#19
eh bro....

i know wat u are talkin about liao...the bar meter in ya camera rite... hehe....u call me i explain.....

i takes a nikon film user to understand this....
gimmie a call anytime...

cheers....
 

dkw

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#20
Climber said:
EH!!! if this thingy is used to measure the "correct exposure" of the thingy then this button --> (+/-) is used to change the exposure also wat. So if we change the "correct exposure" then what is EV in the camera? isit only a METER or isit a thingy that has the final say in shutter speed and aperture?

Now kinda think that it has double uses.
Heh, now you've got it! In manual mode, it acts as a meter. In program mode, shutter or aperture priority, it is used to "anchor" your exposure. I.e., if you fix the "exposure" value you want, and when you shift your shutter or aperture, the reciprocal change will occur for the other variable.

Cheers,
 

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