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The Nikon Matrix Meter 19 August 2001

Caution: If you shoot print film the exposures you see on your prints has nothing to do with the exposure you made in the camera. Exposure is an issue of your one-hour lab's jr. high school technician, not your technique or your negative. Ignore this section entirely or shoot transparencies instead. Only by shooting transparencies or doing your own lab work will you be able to control your final results.

If you are having exposure problems with your prints it most probably was how they were printed, NOT how they were exposed.

If you see muddy, dull, grainy or light shadows with no detail in your prints then you have an underexposed negative; otherwise, the only reason a print will be too dark is if it was printed incorrectly.

INTRODUCTION

The superior Matrix meter is the main reason to choose Nikon over other brands.

Nikon's Matrix metering, introduced as "Automatic Multi-Pattern" (AMP) metering in the FA camera in 1983, was the world's first meter that actually measured exposure, instead of just light. It is one of the most important advances in photographic technology. This meter knows how to make white snow or sand look white, instead of a conventional light meter's making everything look medium 18% gray. It applies the zone system automatically to attempt to render a correct exposure under difficult and contrasty situations. When shooting in a hurry under rapidly changing conditions, which is the whole point of using a small format camera like a Nikon, there is no better way to meter your exposures.

An example of too much scene contrast midday.

No meter can correct for poor lighting or too high a lighting ratio. This confuses many into thinking that their meters are defective, even though the meter is perfect. If you have problems with highlights washing out even though your subject is well exposed, or with shadows going too dark even though the main subject is OK, your problem is with too much contrast in your lighting, not your exposure. For photographs with people, use your Nikon flash under all conditions and you will probably improve most of these problems.

Lighting is the most important technical and artistic aspect of painting, art and photography. Others have already written a lot about lighting, so I won't try to duplicate that here. I like to write about things you can't find anyplace else. It is imperative that you learn to be sensitive to the quality of light, and learn to be patient in waiting for it. This is very, very important!

All the other major SLR makers since about 1990 have imitated this meter under many different names. Canon calls it "evaluative," and most camera makers brag about it by specifying how many sensors they use. Even Leica attempts to copy it. Today's Leica R8 has about the same technical sophistication as the 1983 Nikon FA.

The number of sensors is unimportant. The wisdom that goes into the firmware that interprets the data from the sensors IS what's important.

The original Nikon FA had only 5 metering sensors. Today even the F100's Matrix meter works with the same 5 main sensors, and only adds the 5 spot sensors into the mix for fine tuning. Canon's excellent Rebel 2000 claims 35 sensors; I still prefer the Nikon meter's programming. The Nikon N90 had a whole bunch of sensors right in the very center of the image, which makes for an impressive number-of-sensors spec, but has nothing to do with the meter's ability. Nothing is wrong with the N90's meter; it's just that the N90 sounds like a toy when it runs.

The color Matrix meter of the F5 ought to be extraordinary. This is why Canon contract photographer Arthur Morris has said that the world's best camera is the Nikon F5. I have not tried it, because if I did I'm sure I wind up having to haul an F5 all over the place. I'm being obstinate by not trying the F5, you don't have to be. Meter accuracy is the most important aspect of image quality contributed by the camera, and why I shoot with Nikon.

This article refers to the conventional Matrix meter introduced in the FA in 1983 and continues to this day in all Nikon AF SLRs.

BASIC EXPLANATION

see full original documentation here>>

Guessing your subject type

The Matrix meter first tries to guess what you are photographing (the hard part) and then makes the appropriate exposure calculation (the easy part.)

You may have read that the Matrix meter compares the light reading to "over 30 million billion zillion onboard stored images" or some other baloney. Those images aren't in the camera. What the camera does do is use the experience gained from professional photographers and analyzing many, many photos (that's your 30,000 number) in order to help program the camera's firmware to recognize what sort of photo you are trying to make. Once it has classified your image it then can make the best calculations for your exposure.

The camera classifies images as shown on page 5 of the documentation.

Sunlit white values

These meters all also make use of a very important observation: the sun is always about as bright on a clear day as is it is every other clear day. If a camera sees something above the brightness of a gray card in sunlight (LV15), it knows that it is seeing something lighter than gray. It knows this because it is smart enough to know that the sun didn't just get twice as bright.

When it sees something that needs to be made lighter it deliberately "overexposes" compared to a dumb meter so that the light items look light.

This is simple zone system application; if the meter sees something two stops above where a gray card in daylight would be (LV15 + 2 stops = LV17) then it knows to "overexpose" this section two stops, in order to make it look white instead of gray.

If the Matrix meter sees segments that are really bright, say anything above LV 16-1/3, it just ignores them. It knows that they represent bright highlights or direct sunlight, and should not use them to calculate exposure. It instead puts more weight on the other segments.

Absolute light levels

To guess your subject type and determine what really is white in sunlight the Matrix needs to know the absolute level of light outside the camera. Remember that the light inside the camera will differ from the light level outside the camera depending on the speed (f/stop) of your lens.

Therefor the Matrix needs to read the true f/stop of the lens. The FA camera read that with a special new lug on the back of AI and newer lenses. AF cameras read this electronically. Other cameras have not needed this, since they did not try to guess what sort of subject you were photographing and therefore were happy only knowing how much light made it through your lens to the film.

For instance, the Matrix knows how bright daylight is, so it knows if it sees something that is bright enough to be bright sand in full sun it knows to add exposure to make it look light and not just gray.

If the camera can't tell the actual maximum aperture of the lens then it can't determine absolute light levels and cannot do Matrix metering.

Absolute maximum aperture coupling

Manual AI lenses have a special internal mechanical coupling lug on the back of the lens that tells the F4 and FA what the exact maximum aperture is, like f/4 or f/2.8. All AF lenses have these same mechanical lugs for the FA and F4 (thank you, Nikon), and also have electronic contacts for the AF cameras.

Heck, the camera also wants to know the light falloff of the lens, and I think that's also coded into the depth of the mechanical lug. The camera uses this to get the right readings for the meter segments on the sides of the image. This is entirely different than the lug on the external aperture ring that tells the camera relationship between the aperture you set on the lens and the maximum aperture. I don't think any cameras were ever designed to read the falloff mechanically, just as AI lenses also have a mechanical lug to couple the focal length of the lenses to cameras that were never built.

All AF cameras read the f/number via electronic contacts. Except for the F4, no AF camera has a feeler to read the mechanical lug from the back of the manual lenses, and therefore all AF cameras (except for the F4) will revert to center weighted when you put a manual focus lens or teleconverter on them. This is a defect in the design of AF cameras probably designed to make you have to buy new AF lenses.

I believe that the AF lenses also tell the Matrix about the falloff of illumination so that it can more accurately measure the corners of the image.

Use with teleconverters

The only way to get real Matrix metering on an AF camera is to use a TC-14E or TC-20E (or the new "II" versions). These only work with the exotic AF-I and AF-S telephoto lenses.

There is no other way to get real matrix metering with other TCs on AF cameras other than the F4.

To get Matrix with the manual focus lenses on an FA or F4 you need a TC that has yet another feeler added to it to couple the absolute aperture information mechanically. The TC-201 has this coupling. The TC-200 does not. The manual focus TCs do not give either autofocus or Matrix metering when used on AF cameras.

Oddly this means that to get Matrix metering with any lens other than an AF-I or AF-S lens and a teleconverter you have to use the old F4 or FA and a TC-201 or TC-301 (or I think TC-14A or B). Otherwise you can't get Matrix with a teleconverter and any other AF camera!

When you can't get Matrix on a camera it defaults to center weighted if you have selected Matrix. Most AF cameras tell you this on the meter pattern indicator. The FA does not have an indicator for meter pattern.

From what I've seen, discount teleconverters like the Kenko PRO, Tamron, Sigma and Tokina do not properly couple the maximum aperture to the AF cameras and will confuse the Matrix on occasion, especially in bright light. If your TC lets you get to the marked maximum aperture on your AF camera you have improper coupling. An AF camera should only indicate one or two stops less maximum aperture in the camera than marked on the lens when the TC is used.

What about 3D metering and D lenses?

You can safely ignore this if you are buying your lenses used.

D lenses help the meter a little bit in guessing what you are trying to photograph. It has very little effect.

Because impressionable people mistakenly believe that D lenses serve some wonderful purpose you can get the perfectly good non-D lenses cheap today used.

In making deliberate tests of D and non-D lenses with the same subject at the same time I have seen no differences. The only time I've seen a difference is doing the one thing for which they are good: making of flash photos straight into a mirror.

The only non-D AF lens made today is the fine 50mm f/1.8 AF. It is a bargain.

3D meteriing may safely be ignored.

Color Matrix Metering

The F5 ups the ante by adding sensitivity to color. This, unlike 3D, is very important. This allows the F5 to make yellow as light as it should be, and red as dark as it should be.

Color, along with all the segments in the F5 meter, also allow the camera to guess what your subject is more accurately, which in turn allows the camera to apply a potentially more accurate metering algorithm to your photo.

This feature is unique to the F5 among all film cameras.

TIPS

When to use Matrix

The easiest thing to do is to trust the Matrix meter for everything; it will be correct more often than most people's ability to override a conventional meter.

To understand how matrix metering works requires a knowledge of the zone system (See books in reference section) as well as the EV and LV systems. Once you understand those, then read the documentation on the meters. Nikon has not publicized this much today, which is unfortunate because without this information it is much harder to learn how and why the Matrix meter does what it does.

For technically fluent photographers the Matrix meter is very predictable and easy to compensate when necessary, but it is far more complex than averaging meters. This complexity is what makes the Matrix meter so good, but also what makes it so difficult to learn and why some photographers still don't trust it.

When and how to use flash

Use Matrix fill flash all the time unless you specifically don't want the subject highlighted or frozen in lower light. The Nikon Matrix' ability to balance flash and natural light is unbeaten. Use the SLOW REAR sync mode indoors to allow the background to look natural.

Use the Matrix setting, which on older flashes (SB-22, SB-23) is the default setting and on newer flashes (SB-28) is shown by the TTL symbol and a little five-segment Matrix symbol on the flash's LCD.

Make sure you have plenty of flash power and range in very contrasty places (like shooting into the sun), otherwise turn off the flash. Here's why:

In contrasty light the Matrix meter will reduce the exposure of the ambient light by as much as 2/3 stop to bring very bright highlights down to within the range of the film, expecting that the flash will fill the even darker shadows. This usually gives great results since you usually have enough flash power to fill the shadows.

If you are outdoors and contrasty subjects are out of flash range, turning on your flash can actually result in as much as 2/3 stop underexposure for the whole scene since the ambient exposure is reduced and the flash won't be able to fill in the shadows! Don't worry, you'll see the insufficient flash power indicator flashing if this happens. Just don't presume that only the fill will be too dark because you also may have the ambient light underexposed, too, outdoors. I wasted a few rolls one time shooting up into backlit trees and ignoring my insufficient flash power indicator (the rapidly blinking ready light) thinking that only the fill would be a little darker. All the shots were too dark; I should have just turned off the flash.

You can confirm this effect simply by pointing your camera at a very contrasty scene. Turn the flash on and off while observing the exposure indicated by the meter. You will see the exposure reduce when the flash is turned on in very contrasty light.

What about using AE lock in Matrix?

It works just fine. I do it, although rarely.

The Matrix meter works by first guessing what you are photographing (the hard part) and then setting the exposure accordingly (the easy part).

If you lock it to something else then it is much less likely that the meter can guess correctly what your real subject is. If you are deliberate enough to want to lock exposures it is better to do it with the center weighted meter.

The first Matrix camera, the FA, omitted the lock button for just this reason.

Subjects that can fool the Matrix

The Matrix meter has been fine-tuned for over 20 years. These are about the only subjects that fool it today:

1.) Predominantly light colored subjects not in direct sunlight. Since these are not bright enough in absolute terms (LV16 or above) the Matrix cannot guess that they are supposed to be light. It will tend to render them as gray. If your subject has both dark and light areas the Matrix is fine. If the entire image is a white card in the shade then you'll still have to dial in + compensation to make the white card look white.

2.) Bright overcast skies. These are dark enough that the meter can't tell that you want them to look almost white in your image, because they are below LV16. You will have to dial in + 1 or even +2 compensation if the bright gray sky takes up most of your image, say when photographing flying birds against the bright gray sky.

3.) Deep or dark filters. Remember that the meter needs to know the absolute Light Value of the subject as explained above under "Absolute light levels."

If you put a dark filter like a polarizer over the lens then you may fool the matrix into thinking that you have a different kind of subject because the transmission of the filter is not communicated to the Matrix meter.

If you put a filter over the lens you have just confused the matrix meter. Light filters, like a UV, skylight or A2 (81A) only absorb a third of a stop at most, so the worst-case error these filters will introduce is a 1/3 stop underexposure on snow or other very bright scenes. You can ignore this, and I do.

However, let's consider a polarizer with a 2-stop filter factor. With a polarizer your camera will see what it thinks is LV15 when looking at bright sand or snow, instead of the correct LV17. Because of this the meter can't tell that you have a bright sunlit white in your image, and you may get unintended underexposure.

I don't worry too much about this, but then again I don't often use polarizers.

Remember this if you have very bright conditions.

You may want to make a manual Matrix reading without the filter, AE lock that reading and then add that filter factor as a compensation value after adding the filter. Actually, if you are going to go to this much trouble you may as well just use a Pentax spot meter and a view camera, but this does illustrate potential problems.

This is another reason to choose Nikon brand polarizers: they only lose 1-1/3 stops of light, not 2 as most other polarizers do.

4.) Medium light items in sun, like California stucco. For things you want rendered as Zone VI, a light rendering but not white, some of the earliest Matrix and AMP meters rendered them a bit dark, closer to an 18% Zone V. In these cases you needed to dial in about +2/3 compensation. Modern (F100) matrix meters seem to be OK with these subjects.

Which cameras give matrix metering with which lenses?

All current AF cameras, and most older ones, too, give matrix metering with all AF lenses. None of them except the F4 can do it with manual focus lenses.

Nikon deliberately crippled the AF cameras, except the F4, so that they only give center-weighted metering with manual focus lenses. Nikon probably did this to encourage you to have to buy new AF lenses in order to get the very important matrix metering. The F4 AF camera and FA manual focus camera have mechanical encoders to allow these cameras to read the maximum absolute f/stop from a lug on the lens. This is required for the matrix to function. Since all other AF cameras lack these encoders they can't give matrix metering with manual lenses.

There are fringe factions who attach chips to manual focus lenses to trick AF cameras into giving matrix metering. These probably work.

Nikon adds chips to two manual lenses: the old 500mm f/4 P AI-s, and the new 45mm f/2.8 P, so that these two lenses uniquely give matrix metering on all AF cameras.

To get matrix metering with manual focus lenses use either the F4 AF camera, or the FA manual focus camera.

All manual focus AI and AI-s and AF and AF-I and AF-S lenses give matrix metering on the FA and F4. The only ones that don't are pre-AI lenses from before 1977.

Pre-1977 lenses that have been AI converted will not give matrix metering on the F4 or FA, unless one also adds a special lug to the back of the lens. You can have an ancient lens AI converted for about $25, but that same guy wants about $200 to add that special lug. Forget about it.

Also manual focus lenses only give manual and aperture preferred automation at best on the AF cameras. One does not get Shutter-preferred or Program modes with manual lenses on AF cameras.

The FA camera provides all the P, S, A, and M modes to work with all lenses newer than 1977. This is because Nikon is still good enough to ensure that all new AF lenses still provide all the mechanical lugs to couple to the older cameras. In fact, the latest AF-S 80-200 f/2.8 lens not only works flawlessly on the FA camera, it also has the lug to put the FA into the high-speed program mode for telephoto lenses.

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