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Photography Question 
Morris Turner

Light Meters

I'm new at photograhy. Please explain light meters to me... in non-technical terms! Any suggestions as to brand/type I should look for? Thanking you in advance, Morrie

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3/12/2003 4:38:24 PM

John A. Lind
BetterPhoto Member Since: 9/27/2001
I'll try to keep this as non-technical as possible.

Important Metering Terms:
"Luminance" is the light reflected by something (reflected light).
"Illumination" is the light shining on something (incident light).

There are two types of photographic light meters. The basic one is a "reflected" light meter which is aimed at the subject from the camera position. It measures "luminance" level of light being reflected by the subject. The metering inside a camera measures reflected light.

The other is a reflected light meter capable of being switched over to metering "incident" light by covering the sensor with a special diffuser. In "incident" mode, it is aimed at either the light source or the camera from the subject position and measures the "illumination" level of light falling on the subject.

Regardless of the type of measurement you make (incident or reflected), the basic principle of operation is the same. The two variables are the film speed you are using and the lighting level (incident or reflected) for a particular photograph. The meter has a setting for the film speed which you do in advance. After measuring the lighting, the meter gives you combinations of lens apertures and shutter speeds that will properly expose the film. Within the lens aperture and shutter speed limits of your camera, you can trade how much light the lens allows to pass through it with how long the shutter remains open, and vice versa. This gives you some flexibility in stopping motion and/or controlling depth of field.

There are some pitfalls in making reflected readings if the meter is taking in a fairly wide angle of view, especially if it's wider than what will be in the photograph. Incident readings can be more accurate if they're performed correctly, but they can also be more difficult to do properly under some conditions. With either method, you cannot throw your brain away when using one to set an exposure. Experience in using a meter for a short time helps greatly and it's not that difficult to master.

You will also see features such as "spot" metering, which is a more advanced reflected light metering method. Spot readings measure a very tiny portion of the subject that will appear in the photograph. It's typically used for finding the luminance level of the brightest highlights and deepest shadows. Exposure is then set somewhere between the two using a method to average them.

Probably the biggest name in light meters is Gossen, a German company. Other big names in photographic light meters are Sekonic and Minolta.

-- John

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3/13/2003 7:45:58 PM

Morris Turner   Thank you, John, for such a clear and concise explanation of light meters. You guys REALLY are good!

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3/13/2003 11:17:13 PM

Larry T. Miller   Morris;
John has said it all. You might look at the Weston Master series meters also. Rugged and reliable.

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9/29/2003 9:33:30 AM

John A. Lind
BetterPhoto Member Since: 9/27/2001
  The Weston Master IV and especially the Master V are fine selenium meters (I have a Master V in excellent working condition). Weston was *the* inventor of the modern photographic light meter. Their meters were *the* biggest name in meters prior to being overtaken by Gossen and others (and an eventual decision by Weston to exit the light meter business).

The problem is finding one in good, accurate working condition. Selenium meter cells degrade naturally over time and the meters loose accuracy. There are a lot of duds floating around as Weston has not made these for decades. They can be rebuilt including meter cell replacement and there are a couple of firms that specialize in this. The cost is about $50 not including shipping and insurance.

The only drawback to the Weston Master meters (and all other selenium cell meters) is limited light sensitivity in very low lighting levels that might require exposure times measured in numbers of seconds. For daylight outdoors, even around dusk and dawn, they are excellent meters. The up side is selenium meters do not require batteries to power them.

-- John

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9/29/2003 10:49:22 AM

Larry T. Miller   You're right John, once the sun sinks deeply below the horizon, the selenium cell is tricky. and you're right, during the daylight hours, it's a reliable cell. I use a Weston Euromaster and a Euromaster II. Both are accurate, even the old Euromaster. I have an old Ranger 9 I took out this wwekend to test it's accuracy. We'll see what the celluloid produces. Just hate to rely on batteries!

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10/6/2003 6:43:38 AM

John A. Lind
BetterPhoto Member Since: 9/27/2001
  Interesting . . .
I also have a Ranger 9. Great "spot" meter with a little more sensitivity at lower light levels and useful even if the spot is a wider angle than current spot meters have. A quick scan around a scene with one gives me a good idea of the light value range spanning broader highlights and shadows. For very low light levels such as urban streets at night I use an older, analog Gossen Luna Pro F (it's very accurate).

-- John

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10/6/2003 8:19:02 AM

Larry T. Miller   John;
Got those slides back using the Ranger 9 meter. Was impressed with them. Weston sure did know how to build a meter. I'm using (2) 1.4V batteries instead of the of the 1.35V they recommend. I adjusted the ASA reading from 100 to 50 and the slides came out well. I had hear to do that proceedure somewhere. I took my Quantum Calculite XP meter out recently to see what accuracy that brings. Still don't like using batteries though. Oh well....

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10/14/2003 10:25:48 AM

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