2016 December 7    Film   Miscellaneous


In the article "Grit, Grain, & Contrast", we looked at using an incident light meter for shooting film at night.

Now we'll look at using an incident meter in the daytime.  One of the questions that I'll try to answer is, "Does an incident meter have any real advantage over the one in your camera?"

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In This Article

Incident Metering:  What Is It?

Incident vs. Your Camera

Incident vs. Your LCD

Incident Metering In Daytime

The Correct Angle

Like Tools In a Toolbox


Incident Metering:  What Is It?

A reflected-light meter reads the amount of light that's bouncing off your subject. 

Incident meters read the amount of light falling on the subject.  This is fundamentally different, because the measured brightness does not depend on the subject.

If you see a light meter with a white plastic hemisphere or dome, it's an incident meter.  (These can usually meter reflected light, too, if you remove the dome.)

So, why bother with an incident meter, when our in-camera meters work just fine?

The answer is that sometimes they don't.  Reflected-light metering can be fooled easily.  Go ahead and stand outside when the ground is covered in snow.  Try to take a picture of it at +0 EV.  If you rely on reflected-light metering, the picture will be underexposed.

Dark backgrounds and objects have the opposite effect;  the picture will tend to be overexposed. 

Incident Metering vs. Your Camera

At night, "matrix" and "evaluative" metering can be fooled by light sources that are in the scene.  The result is that your subjects will appear too dark in the photograph.  In the daytime, the same thing can happen if there's glare in a scene, or the actual sun is visible in the picture.  (Don't look at the sun through a telephoto lens.  For real.)

Another very common situation is to have your subjects sitting in the shade, while the background is lit by bright sunlight.  Sometimes you have to take the picture that way.  The in-camera meter can get it very wrong.

That could be a wasted sheet of 4x5, or a 6x7 frame.  Even 35mm slide film is not dirt-cheap anymore, so it pays to meter your scenes correctly.

In a typical scene, the amount of light reflected from different surfaces could be all over the chart.  The amount of light falling on that scene is... the same for the whole scene! 

I think it comes down to choosing the right type of meter for the scene.  However, if it's a scene where you can walk up to your subject and use a meter, I would say the incident meter has the advantage.  It also has the advantage if your subject is against a light-colored background, or a very dark one.  Many stone walls, houses, and other buildings are brighter than neutral gray.  The incident meter will give a more accurate reading there.

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Incident vs. Your LCD

You could just shoot a lot of digital pictures, then pick the settings that worked best.  Problem is, bright sunny days tend to produce a bias toward overexposed photos. 

That's because in bright sunlight, the photos appear darker than they really are when viewed on the LCD screen.  So when you get home, the "good" photos might actually have clipped highlights, etc.

Use an external meter, and you can probably get it right in one attempt. 

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Incident Metering In Daytime

If your scene is lit uniformly-- no matter if there are bright and dark objects-- it's easy.

Full sun, full overcast, or full shade:  incident metering will probably get it right.

The tricky part is when you're standing in lighting that's not the same as what you're trying to photograph.  This can easily happen at the edge of a forest, near a building, or anywhere else there is mixed sun and shade.

For situations like these, the surest way to get it right is to move around until you're standing in exactly the same type of light as your subject.  So, if your subject is in the shade, walk over there into the shade and meter with your incident meter.

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The Correct Angle

Standing near your subject, hold the light meter vertically.  Face the dome toward the camera.  If you don't have the camera on a tripod, just face the dome toward the location where you'll be standing with the camera. 

If you point the dome toward the daytime sky or an overhead light source, you'll probably get underexposed photos.  This is kind of elementary, but it's not necessarily intuitive.  That's because some of the old light meters were actually meant to be held horizontally.

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ISO Setting

If you shoot film at box speed, just set the correct ISO rating as printed on the film packaging.

If you push or pull the film, be sure to set the meter at the E.I. of the film.  You know how all those guys like to remind you that a pushed film is not really a higher ISO speed?  Well, the meter doesn't care about technical details like that.  If you're going to push film to 3200, then set the meter at ISO 3200.  Otherwise you will have to do a conversion to figure out the correct settings, and who wants to bother with that?

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Like Tools In A Toolbox

Does an incident meter do everything you'll ever need?  No, definitely not.

A good incident light meter is one tool in the toolbox, but it's an important one if you shoot film.  It's also useful even if you're digital-only.  What makes this tool even more versatile is that you can remove the white dome and you'll have a reflected-light meter.  At least one brand of meter has an add-on spot finder available, so you can use the meter as a 5-degree spot meter. 

That said, if you're serious about landscape photography, it would actually be worthwhile to have two different external meters.  I'd choose an incident-light meter like this one, and for spot metering the Pentax digital spot meter is what many accomplished large-format photographers use. 

A film photographer could handle just about everything conceivable with those two light meters.

For someone just starting out, or progressing from in-camera meters, I would say the incident-light meter should be the first choice. 

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Incident metering requires that you are standing in the same light as your subject.  This is not going to work for every type of scene, but it sure works for a lot of them.  If you ever have to deal with expanses of snow, sand, or other light-colored landscape features, an external light meter is almost not optional.  As you work with larger sheets of film, you'll probably not want to waste it on metering errors.  Metering correctly is a whole lot better than messing around with exposure compensation, which you can easily get wrong.

What light meter to get?  I would choose a good incident-light meter such as a Minolta, Kenko (basically same as the Minolta, but newly-made), or a Sekonic like this one.  (The Kenko does have 5-degree spot finders available for it, but I haven't tried them.) 

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