Why and how do I meter?

[Steveo555]

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?

 

[Big Mike]

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.

 

[Derrel]

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.

 

[Dominantly]

Also in my sig...

 

[mostly sunny]

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!

 

[Bitter Jeweler]

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

 

[Dominantly]

Quite possible... Then telling everyone about it.

 

[ann]

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.

 

[Proteus617]

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

 

[Bitter Jeweler]

That actually sounds like a fun game.

 

[TiaS]

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.

 

[Proteus617]

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.

 

[flyin-lowe]

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.

 

[Bitter Jeweler]

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

 

[Derrel]

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.

The above description is not the way modern Nikons (1984 onward to 2010) perform their light metering. Also, the description that the meter would use a "light color gray as the middle tone" is also not correct; a light meter that would be able to select or chose a light color grey would have to be in the presence of a light-colored grey object,right? No, the above statement is inaccurate on a couple of levels.

Modern Nikon cameras with 3-D Color Matrix Metering and aware of BOTH color, and reflective values!!!! The majority of cameras from other companies are wholly color-blind, and can not differentiate between a black sandy beach or a white sandy beach or a gray sandy beach: there are beaches of all three colors around the world. What an old-school light metering system does is it "averages" whatever it is pointed at so that the "average" result will be an 18% (well,actually 12.5% ARV, but that's technical) Average Reflectance Value: so, to make a black cat look black, using an "old-school" color-blind light meter, we'd need to UNDER-expose by about 1.5 stops to make the black cat look black. If we pointed an old-school, color-blind light meter at a white snowbank in sunlight, the average reflectance exposure would turn that white snow into a muddy, gray mess, so we'd need to OVER-expose by at least 1.5 stops, up to 2 stops or even a slight bit more, to make the snow look "bight and white" and not muddy grey.

The original poster spoke specifically about a Nikon camera, and as a long-time Nikon user, I'm pretty familiar with how their cameras meter in Matrix mode; there are some slight differences among models,however,and not each model performs identically. Nikon owns the patent for RGB color metering; that is why all other cameras are color-blind, EXCEPT the new Canon 7D. Canon has found a way around the RGB color pattern analysis, by using an RGGB or 4-color matrix, with a Green and Green-Yellow, 4-color Bayer,and so Canon is now touting its new color-aware and distance-aware light metering in the 7D model.

In another forum I am on, an old-school Texas shooter was trying to use the old-school guidelines of over- and under-exposing by metering the highlight values with his Nikon D300,and then applying the Modified Zone System type approach Bryan Peterson and many others describe. The problem with the idea of "middle grey" is that 90 percent of all cameras and reflected light meters work based upon the idea that **whatever** is measured is basically like the Kodak Gray Card, and so the user must UNDER-expose black cats and OVER-expose snowbanks, to get the proper offset because what was measured was in fact **not** an 18% Reflectance Gray Card. Because this old-school Texas shooter was treating a color-aware Nikon D300 meter just like his 1975 "dumb" Pentax Spot Meter, his exposure offsets were giving him totally screwed-up results with his D300. That method had worked for years with his film cameras.

Newer cameras that are not modern Nikons and not the Canon 7D are basically color-blind. However, there are sophisticated image analysis routines that can accurately 'guess' how to best expose scenes based on a wide array of data points available to the camera, like, for example: the camera clock time and date( EX: 4:47 AM, Christmas Day, Northern Hemisphere vs July 4, 1:30 PM), EV level (night-dawn-noon-afternoon), white balance, presence of extremely bright sources AKA the sun, size of extremely bright source in relationship to lens lens focal length in relation to focus distance (EX: small extremely bright, upper left hand corner, Infinity distance bright object, 5:45 AM, 95 percent of frame is 16 EV values lower than bright area located in upper left corner = SUNRISE attempt!). So, ,even if a camera can read only reflectance or EV values (ie brightness values), a modern "smart camera" in Evaluative metering modes stands a pretty good chance of being able to take into account all the variables available, and then use a 30,000 or more actual photograph data set to help the metering system analyze many variables to get the right exposure. Pro-level Nikons of the D2 and newer generations have you enter your City location in the clock/date/time for a reason,namely exposure calculation assistance. Sunrise and sunset times are easily known and entered; shots made between 9:00 PM and 5:00 AM throughout most of the year will have artificial or flash white balance if the EV value is "high-ish", ie, lighted by more than moonlight values....computers are dumb, yet smart...

Bottom line: in "Evaluative Metering" modes or the "Scene" metering modes, some of the old-school ideas about 18% gray, AKA middle gray, and all that are not always valid,with every camera; the "old-school" idea also had a color slide versus color negative aspect to light metering. Modern digital cameras now shoot only one type of film: what would be color slide film, metering wise. Like Big Mike said, metering can be a very involved topic. With some cameras, like the newer Nikon's, the Matrix metering is very hard to use with the exposure compensation methods that old-school light metering methods were based upon, and that is why I said it is silly (stupid) to use Matrix metering with a Nikon in a manual exposure mode.

One thing MANY cameras have, is sensitivity to the actual focus point in use. Both with the metering and exposure settings the camera does with natural light, and with flash light. So, again, yet another complex issue. It's one reason that understanding one's own camera, and its manual, is so important.