Metering Techniques:
How to Use a Spotmeter for Digital Photography


In my Introduction to Handheld Exposure Meters tutorial, I explained that reflected light meters do not know if your subject is a light colored scene, a dark colored scene, or a middle-toned scene. Because the meter cannot know what it is being pointed at, the manufacturers calibrate them to assume that anything you point them at is a middle gray tone.


Middle gray tone that reflected light meters are calibrated for.

A whitewashed brick wall that I photographed using the exposure recommended by a reflected light meter. Because the meter assumes that anything it measures should reproduce as a middle gray, the white wall has been rendered a middle gray.


As the example above shows, anything that is lighter than middle gray in tone will be underexposed by a reflected light meter's readings. Conversely, anything darker than middle gray will be overexposed. Because we often photograph things that are predominately light toned or dark toned, it would seem that the reflected light meter is useless by comparison to the incident light meter. Incident meters ignore the subject; reading instead the light that falls on the subject. This means the meter cannot be fooled by very light or dark scenes into giving incorrect exposure.

The incident meter has its own set of limitations. It does not work for backlit scenes or for photographing trans-illuminated or self-illuminated subjects, such as stained glass windows or neon signs. A reflected light meter can be used for those types of scenes, and it can be used successfully for any type of subject so long as you understand how it works and how to interpret its readings to make a subject render with the correct tonal values.


Spot Meters

The secret to effective use of a reflected light meter is to read individual parts of the scene and then use those readings to decide on an exposure setting for your camera that will place your subject on the correct tonal values for it.

A standard reflected light meter reads a fairly wide view, typically a 30-40 degree angle of view. If you want to measure individual parts of the scene, you'll have to walk close to the subject and carefully point the meter so that you don't cast a shadow from the meter or your body on the area being read. This is a pain to do, and can be difficult or impossible if the subject is located far away, or in an unsafe place (example: inside a lion cage at the zoo).


Spotmeters. Pentax Spotmeter V, Sekonic L-758DR, Minolta Flash Meter IV with 5 degree viewfinder, and Gossen Ultra-Pro with 7.5-15 degree spot attachment.

Some meters from my collection.

The Gossen Ultra-Pro at the top left is a wide-area reflected meter with Gossen's 7.5/15 degree spot attachment mounted.

The Pentax Spotmeter V at the top right is a true one degree spotmeter. An older model, it is large and heavy compared to modern meters and it does not have a digital readout.

The Sekonic L-758DR is a modern combo meter that has both a true one degree spotmeter and an incident light meter all built in to one unit. The most convenient meter you can get.

The Minolta Flash Meter IV in the middle is primarily an incident meter; but offers a large system of accessories to expand its capabilities, including the 5 degree spot attachment shown.


The solution is a spotmeter. A spotmeter is a reflected light meter that has a lens and viewfinder so that you can look through it and aim it precisely at the subject area you want to measure. Most have a narrow one degree angle of view for the light sensor, which is marked in the viewfinder by a circle.

Dedicated one degree spotmeters are no longer being made. Today, they're built into high-end combo meters that offer both a one degree spot meter and an incident light meter all in one. This is very convenient, since you can carry both types of light meter in a single unit.

Some incident meters and some regular reflected light meters offer a spot viewfinder accessory, like the ones shown above with the Minolta Flash Meter IV and Gossen Ultra Spot.

These work, but have some serious disadvantages. They are not really small enough spots, and so can still require you to walk up close to your subject; they reduce the meter's low-light measuring ability; they do not have a readout in the viewfinder like a true spotmeter; and they're less precise because the meter cell and the viewfinder have separate lenses.

One degree spotmeters, including those built into incident/spot combo meters, are like an SLR. The viewfinder and meter cell see through the same lens.


Exposure of a white building determined with a incident light meter.

The viewfinder of a typical one degree spotmeter. In the center is a circle that marks the area that the meter actually sees when you take a reading. Most modern spotmeters have a digital display in the finder that shows you the ISO setting, shutter speed, and aperture.


On the next page, I'll show you how you can control how light or dark your subject will be rendered by changing the readings that your spotmeter gives you.


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©2018 Christopher Crawford