# Why and how do I meter?



## Steveo555 (Feb 24, 2010)

Can someone please explain what it is meant by metering? Why it will help my pictures and certain situations in which is should be used. How do I use the AE-L and AF-L buttons on my Nikon D5000? I read the manual but still do not understand it. Can someone also give me example in which I would want to use the matrix, center weighted, and spot?


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## Big Mike (Feb 24, 2010)

Metering can be an involved topic.  Definitely something worth delving into.

To say it simply, metering is measuring the light to find your exposure settings.

Firstly, pretty much all modern cameras have some sort of automatic metering system.  When you start to press the shutter release button, the camera 'meters' (measures) the scene (light) it sees through the lens (TTL).  
The camera is calibrated to think that the scene is average/mid toned (also called 18% grey).  So it gives you settings (shutter speed, aperture & ISO) to give you an exposure value.  
You can use the priority modes (A or T) to lock in one setting, the camera will use it's meter to give you the other value.  

The different metering modes on your camera, affect the area that the camera measures.  Matrix uses most of the scene, centre weighted give more priority to the middle and spot uses only the centre are, ignoring the rest.  

If your scene is not 'average', then the camera might not give you the best settings.  For example, if you are shooting a person standing in a field of snow, all the bright white snow will make the camera think that it's really bright and thus is will give you less exposure.  This will cause the person to be too dark, and the snow might look muddy.  In this case, you could use the spot meter setting and get close to the person.  That way, you can only meter/measure the person (ignoring the snow), and probably get an exposure that will work better for you.  

The same principle applies to all metering.  If the scene isn't average, you need to realize what the camera is measuring.  Often, you might need to compensate the exposure value (change the exposure) away from what the meter thinks is right.

A lot of people suggest the book 'Understanding Exposure' by Brian Peterson.


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## Derrel (Feb 24, 2010)

Here's a 1,000 page Complete Guide to The Nikon D5000, plus a 128 page handbook

Complete Guide to the Nikon D5000

Nikon's Matrix metering, which they invented in the early 1980's, was the first of its kind. Ever since then, Nikon has refined and improved it, to the point where snow scenes like Mike described above are not much of a problem--the camera is not color-blind,like most other brands of cameras are, so a Nikon in Matrix is ALSO reading the Red Green and Blue component values (RGB) of the light, in addition to its brightness/reflectivity. That means that in Matrix mode, a modern Nikon using a modern lens will perform a very sophisticated scene analysis, and will generally give a nearly perfect exposure without the need for the photographer to interpret the exposure metering. SO, Nikon's Matrix metering is for automatic shooting, where you want to point the camera, and have the camera evaluate the scene, and it will do it almost perfectly over 90 percent of the time.

Center-weighted metering is an old Nikon system based on a 60 percent "weighting" or "bias" to the scribed, 12mm diameter circle in the center of the AF screen, with the remaining 40% of the bias spread thoroughout the entire balance of the frame. On more-sophisticated Nikons, one can further concentrate the center weight by choosing an 8mm or a 6mm circle--not sure if the D5000 offers this. Center-weighted metering is good in Manual mode, since it allows you to point the camera at the area you want metered, and to adjust the shutter and aperture to get the desired exposure. DO NOT USE MATRIX METERING in manual exposure mode--that is totally,totally counterproductive for the most part. Matrix Metering in manual modes is silly (stupid) because the camera is making an overall,total, whole-frame estimate.

In an automatic metering mode, using center-weighted metering, you aim the meter to the area that will provide the metering you think you want, then press and hold the AE Lock button,then re-compose and shoot. This allows you to point the camera at brighter or darker areas of the scene, to artificially "sway" or :"bias" the meter reading. You can also use it the old-school way: point the camera in CW mode in A or S mode, and watch the exposure range indicated in the finder as you move the camera across the brighter, middle, and darker areas of the scene. This will give you a quick idea of the overall, total range of exposures. Then, after you have an idea of the brightness range of the scene, you will decide where to aim to get the **desired** bias in the shot, then press and hold the AE lock button and shoot.

The AE Lock button works great in automatic modes, using center-weighted or Spot metering modes. SPOT metering is for experts. Spot metering will mess up more shots than it will help, until you really know how to meter.


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## Dominantly (Feb 24, 2010)

Also in my sig...


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## mostly sunny (Feb 24, 2010)

Off topic, but remember when I thought I had to go buy a meter.. Cause I didn't know there was one on my camera..

= ) I used it all the time now to meter light....:hugs:  Aww, group hug-- Thanks!


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## Bitter Jeweler (Feb 24, 2010)

Mostly Sunny, I just got a mental image of you randomly metering light, throughout your day, for no reason. :lmao:


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## Dominantly (Feb 25, 2010)

Quite possible... Then telling everyone about it.


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## ann (Feb 25, 2010)

bitter, we used to do that all the time many years ago.

played games to see who could come close to "reading" the light without a meter then checking it with the meter.

i had a friend who could read the light down to 1/2 sec without a meter.

In fact, if i am remembering correctly, Edward Weston did  not use a meter.


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## Proteus617 (Feb 25, 2010)

I usually have a meter in my pocket.  You can get pretty good at "guess that EV" and it comes in handy.


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## Bitter Jeweler (Feb 25, 2010)

That actually sounds like a fun game.


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## TiaS (Feb 25, 2010)

Correct me if I am wrong, but this is how I understand it. The camera takes in the different light settings from your frame, using a light color grey as the 'middle tone'. From there, it exposes your shot. Many photos have a part that is just too dark while the sky or snow is blown out and way to bright. 

When you see a picture of a silhouette, it is because the camera metered off the sky. When you see a picture where the sky is blown out and way to bright but the subject is perfectly exposed, that is because you metered off the subject. 

This is how I understand metering. If I am taking a picture of someone in the snow or when they are standing in the shade with the sunny sky showing in the background, I lock my exposure on the sky, which stops it from being blown out, which makes for a more even metering. Play around with it and you will learn how to make  your subject a silhouette and how to stop the sky from blowing out on those days with uneven ligthing and reflection.


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## Proteus617 (Feb 25, 2010)

TiaS said:


> This is how I understand metering. If I am taking a picture of someone in the snow or when they are standing in the shade with the sunny sky showing in the background, I lock my exposure on the sky, which stops it from being blown out, which makes for a more even metering. Play around with it and you will learn how to make  your subject a silhouette and how to stop the sky from blowing out on those days with uneven ligthing and reflection.



Depends.  If a person is your subject an blown sky is bright sky but a blown highlight on a face is a bad photograph.  Not many are going to complain that there could have been more detail in that cloud top left, but the glare on the cheekbone is info lost and gone forever.


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## flyin-lowe (Feb 25, 2010)

I kept hearing people say "you need to read understanding exposure". I finally did and now realize that 90% of the questions asked on here are covered in the book with examples and with easy to follow instructions and techniques.  I read it twice and can't recommend it enough.  Every newbie should have it, and we were all newbies at one time.


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## Bitter Jeweler (Feb 25, 2010)

flyin-lowe, isn't it funny how easy it is after you read that?


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## Derrel (Feb 25, 2010)

TiaS said:


> Correct me if I am wrong, but this is how I understand it. The camera takes in the different light settings from your frame, using a light color grey as the 'middle tone'. From there, it exposes your shot. Many photos have a part that is just too dark while the sky or snow is blown out and way to bright.
> 
> 
> 
> ...


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