Light meters

blick

I just saw an old light meter; it's a Weston Master V. Do you think this would be a good extra to my kit, or is my camera's meter just as good?
Many thanks.

ohyeahar

I never found myself in need of an external light meter, so my opinion is probably biased.

I feel like a light meter is crucial if you want your exposure to be perfect when you release the shutter. This makes a lot of sense back in the film days, but since we’re all shooting digital, you can just let your camera’s light meter to figure out the exposure and then immediately review it to see if it’s good. If not, you can easily adjust your exposure manually up or down. That seems faster and more efficient than dealing with an external light meter.

bruto

I wrote a long response which my computer ate, and then had to do something else, so here goes another try.

Back in the day, the Weston Masters were very good, the V one of the best, but much has changed. To begin with, the selenium meter, though it is happily battery independent, is not very sensitive in low light. In addition, the instrument itself is a pure averaging meter, which sees basically all that you see when you look out. Its coverage is very wide. If you are using a narrow lens which does not include a lot of sky for example, it will underexpose because it sees a lot of sky. In "reflected light" mode (pointing toward the subject) a meter like this is more a starting point than a final arbiter. You must then decide yourself whether your subject needs the starting exposure tweaked. For difficult subjects, backlighting, etc., you cannot simply aim and set.

In "incident light" mode, the meter is more useful. To use it thus, it must include the white "invercone" accessory, which snaps over the sensor window. For this, you place the meter where your subject is and aim it back at the camera. It then tells you just what intensity of light is falling on the subject from the point of view of the camera without regard for the rest of the scene. Incident light readings are still used for static subjects, such as studio shots of models and so forth, where the photographic aim is to expose a particular thing rather than a scene. Needless to say, this only works if you can actually take your meter to where the subject is. You can't incident meter the Grand Canyon!

For normal use, the camera's meter is faster to respond, more sensitive, and because it "looks" through the lens, it meters only what the lens sees. Since you can also vary the meter's settings and choose spot and center-weighted averaging mode, there is little need for anything else.


Learning exposure with a meter like this has its merits. The dial provides a good visual lesson in the different shutter, aperture and ISO combinations that are equivalent. Watching the needle move as you change direction and so forth, can be quite informative in a way that automation is not; but it's not the most efficient way to get a picture.


The Weston meter dates from a time when most cameras had no meters at all, and both apertures and shutter speeds were varied by full stops (no stepless shutter speeds and third-of-a-stop aperture controls). I often use older manual lenses that do not operate the meter at all on my D3200, but still find that with educated guesswork as a starting point it's quicker to read the histogram after a shot and make adjustments as needed than to operate a separate meter. The histogram tells you what you actually got, and not just what you were supposed to get; a luxury film users never had.

Finally, the Weston V is getting pretty old. Though they are well made, they can lose sensitivity over time. You can get one repaired and re-calibrated if you send it off to a specialist shop in California, but it's not that cheap.

I have a Weston V, by the way, and it's nice. Very well made, but not as it happens my favorite old hand held selenium meter. That honor goes to the Gossen Pilot II, which has an incident light shutter built in, a hard shell case that opens with a snap, and the ability to recalibrate it as it ages. I don't use that with my DSLR either.

blick

Thanks, a lot very informative for me. I think my old camera had this type of meter built in. It was a Yachica Minster D and is still in working order.

bruto

As it happens, I have one of those too. The Minister D was a relatively low entry in the Yashica lineup, with a very sharp lens and good manners; a great bargain for those who did not need the fastest lens or highest shutter speeds more expensive Yashicas had. The meter was a CdS (Cadmium sulfide) cell powered by a battery, the now banned mercury cell. Modern cells will work, but overexpose some unless you compensate by adjusting the ISO setting. It was, like the Weston, an averaging meter, and did not read through the lens. Because the lens was fixed, the makers were able to make the meter's angle of inclusion more or less the same. That type of meter was generally considered more accurate and better in low light than the earlier selenium cells, and can operate through a very small window.

blick

Thanks for the info. Still thinking of buying the Weston Master V just to learn aperture and speed. It seems like a bargain at £10.

bruto

One thing a light meter like that does better than anything is to graphically show what shutter speed and aperture combinations are equivalent in exposure value. When you set the meter to the EV of the light it reads, you see the whole display; basically every valid combination that will give you that exposure. The dials of a light meter are kind of like a circular slide rule for all the relationships between aperture, shutter speed and ISO.