# how to calulate the right exposure ?



## junqi (Mar 16, 2015)

Hi all,

Can anyone advice how can i calculate for the correct exposure during sunny light, cloudy, night time etc. i always use iso 200 only day light and f3.5 and with shutter speed 1/800 and if it is underexposure will decrease the shutter speed. Is there anyway to calculate to get the correct exposure be it cloudy, sunny, Night time or indoor ?

Thank you


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## Alexr25 (Mar 16, 2015)

The best way is use an exposure meter, either the exposure meter built into most camera or a hand held exposure meter.
If you don't have a meter then using the "sunny - 16 rule" will get you close to the correct exposure.


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## junqi (Mar 16, 2015)

Alexr25 said:


> The best way is use an exposure meter, either the exposure meter built into most camera or a hand held exposure meter.
> If you don't have a meter then using the "sunny - 16 rule" will get you close to the correct exposure.


By using the exposure metering how can i know that it is the correct exposure i want ?


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## Alexr25 (Mar 16, 2015)

Does your camera have a built-in meter or are you using a hand held meter?
The exact method of taking an exposure reading will depend on the type of meter you are using and if it's the camera's built-in meter the metering mode the you are using.
In either case the camera or meter manual should tell you how to use the exposure meter to get the correct exposure and you can find plenty of useful information if you google "using exposure meters".


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## weepete (Mar 16, 2015)

Using the in camera metering system change your settings until the meter reads 0. In some situations (where you have a lot of lights or a lot of shadows you may need to use some exposure compensation to get the correct exposure, as your cameras meter is designed to expose correctly for 18% Grey. 

If you are unsure where to start quickly switch your camera to Auto or P mode and note down the settings. That can then be used as a starting point and you can change to a different mode and match the settings snd fine tune them to get where you want to be.

Then you want to learn to read your histogram and that's the way to check whither your exposure is near where you want it to be.

I'm assuming you will be in evaluative or CWA metering mode most of the time. I dont really use partial metering and my method for using spot metering is different again.


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## fjrabon (Mar 16, 2015)

Use your camera's meter in its smallest spot mode metering and then find something in the scene *you* want to be average brightness (middle grey). With your spot meter pointed at just that thing, zero out your meter by adjusting your settings. 

After you've done that you can feel free to compose your shot as normal as long as the lighting doesn't shift, knowing your exposure is set how you want it.


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## bigal1000 (Mar 16, 2015)

junqi said:


> Alexr25 said:
> 
> 
> > The best way is use an exposure meter, either the exposure meter built into most camera or a hand held exposure meter.
> ...


Because the meter reads the light and you set the camera accordingly it's that simple


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## Gary A. (Mar 16, 2015)

Junqi ... there is/maybe/isn't a big difference between proper exposures and the light meter.  A light meter is a guide, depending how the light meter is setup and how your subjected is lighted will determine how accurate your setting are according to the meter's recommendations.

You should read a book or two on metering. It will go a long way on understanding how a meter works and how best to use your meter.

Firstly, a meter will only give you medium gray (18% gray). If you fill your viewfinder with a white wall, center the needle and take a shot. That white wall will be a muddy, 18%, medium  gray wall. If you fill your viewfinder on a black wall, center the needle, take a shot ... the meter will turn the black wall into this medium gray, 18% muddy wall. 

So you have to 'out-think' your meter. The white wall need to be overexposed to become white and the black wall needs to be underexposed to become black. Knowing how much to under/over expose is part of the photographic learning curve. Shooting in spot meter mode is helpful to determine how much light is hitting your primary subject and in manual, it is easy to adjust/compensate for 18% gray by over-under expose.

As an example, grass is normally about 2/3rds to a 1 full stop darker than 18% gray. The photographer reads off the grass and underexposes around a stop. The palm of your hand is about 1/2 to 2/3rds a stop brighter than medium gray, so you fill your viewfinder with your palm, center the needle, then open up about a half stop from that reading. You have make sure that whatever you are reading is similarly lighted as your subject.

You can purchase a 'Gray Card', which is colored to 18% medium gray. Metering off the gray card will give you the correct reading every time. If your shoot a portrait, have the subject hold the gray card, fill the viewfinder with the card, center the needle and viola, the subject (gray card) and the meter are now in sync, perfectly match.

Understanding how your meter works is fundamental for consistently capturing the exceptional image.


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## soufiej (Mar 16, 2015)

Yep!  What they said.  You can trust your camera or your meter - until you can't.  The camera does what you instruct it to do and, if you haven't set the camera to be correct, it never will be.  Change just the metering method of your camera and you'll likely change the results you achieve.  Grey cards are about getting the correct exposure and you should get one and understand when and how to use it properly. 

However, the technical aspect of photography says every situation is different  and every shooter sees the situation unlike the last or next.  You could always use the bracketing function of your camera to get a better idea of what you prefer to work with in your computer during processing.  Make notes of when you use bracketing so you know what you're seeing later.  Note when you are deviating away from what the camera tells you is "correct" exposure.  The broader the dynamic range of the image, the more compensation will be required.  All the more reason to use bracketing and to keep track of the changes you make which are not reflected in basic shooting data.   If your camera can display a histogram before you take the shot, learn how to use it to your advantage.  It's a bit daunting at first but eventually will become one of your best aids to correct exposure - that, along with your head saying "do this".

I often suggest a student photographer  should begin by letting the camera do what it determines is the best shot.  Work for a while in full Auto mode, but work smart.  Keep a pad and pencil with you to take notes and keep track of the shooting data, particularly the metering mode being used.  When you get home and load your images into the computer, pay attention to what you feel the camera did right and what could have been improved.  Begin to formulate your ideas for how to get yourself away from full Auto.  If you're in doubt about a difficult shot, switch to Auto and check the settings.  Then adjust accordingly based on your experience or, at first, your best guess based on what the camera is telling you.  In a sense, there is no "right" exposure, only the best exposure you can make for your use.   Using fill or bounced flash will certainly require a slightly different exposure setting than full midday sunlight.  Shooting at different times of the day or in rapidly changing conditions can mean you are going to be making a good number of compensations.  Don't sweat getting every shot correct.  You'll probably fail at that for a long time.  Work as best as you can but keep track of how you work.  You aren't going to get this in a few days of shooting.   

Do your homework though.  There are plenty of sources for information regarding exposure.  A simple search engine is all you need.  Then grab that pad and pencil and get out with your camera to do the hands on work involved.


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