This is a follow-up question to one I asked a while ago on a cheap, small lightmeter. I'm thinking of buying either the Voigtlaender VC (silicon) or the Gossen Pilot 2 (CDs) meter. What is the difference between a silicon and a CDs meter? Which is better for lowlight/evening street photography?

-- Ron Gregorio (gregorio@ksc.th.com), December 30, 2000

Answers

Ron, first of all the Gossen Pilot 2 is NOT a CdS meter, it is a selenium meter (with the transparent honeycomb grid)which requires no batteries but has 3 faults: 1)it has decreased low-light sensitivity but is fine for daylight use. 2)it gets "temporary fatigue" from constant exposure to bright light, a good idea to keep it in the case or pocket until time for use. 3)the measuring angle is quite wide making selective readings all but imnpossible unless you can get really close to the subject. On the plus side, it never runs out of juice, and it has a built-in incident adaptor.

CdS (Cadmium Sulfide) cells (rarely used anymore but found on many older meters)have increased light sensitivity over selenium cells but are somewhat sluggish in reacting to changes in light compared to Silicon.

Silicon cells react instantly to variations in lighting.

If you are looking for a tiny clip-on meter with a narrow angle of acceptance (for a meter-less camera like a Leica or Hasselblad) look no further than the Sekonic L-208 Twin-Mate. It has the Silicon cell, an angle equivalent to a 90mm lens, and something none of the others have: a reading-lock button so you can meter at eye-level where you can aim the meter at the exact subject area you want to meter.

-- Jay (infinityft@aol.com), December 30, 2000.

In a hand-held meter, I don't think there's much practical difference between CdS and silicon cells, although the silicon meter will probably be newer and may be in better shape. Both are quite sensitive and accurate if in proper adjustment. Response time with silicon cells is very much faster than with CdS, which is critical in an autoexposure camera system but not real important in a handheld meter. A good brand (they don't get much better than Gossen) in either type should serve you very well.

rick :)=

rick_oleson.tripod.com

-- rick oleson (rick_oleson@yahoo.com), January 01, 2001.

CdS cells have a spectral response much closer to film than Silicon. Even the newer Silicon cells have very poor response to blue light, and are over sensitive to red and Infrared.
On the other hand, CdS cells are non-linear, and need better circuit design and calibration if they are to be accurate over the entire range of the meter.
You pays your money and takes your choice, but for my money the CdS cell is less likely to give you any nasty surprises.

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 03, 2001.

Aside from the technical information, which has been discussed already by others, you need to learn good technique for metering in lowlight, available light photography.

First, decide what is the subject of your photo, and expose for it. No film is going to render a general night street-scene, for example, as your eyes do. There may be storefronts with bright signs, but with dark doorways, and a very dark sky, and interesting people walking along a sidewalk, some close to streetlamps, some farther away, with all this complicated by the headlamps of passing cars. Since light falls off by the square of its distance, a person standing close to a streetlamp may easily be lit 8 or more stops more brightly than another person in the same scene. Your eye adjusts rapidly as you glance from point to point, but the film can't.

Tricks help. If a person under a streetlamp is important to you, meter on the person. If he is across the street and you don't have a spot meter, just meter off your own hand a similar distance from a streetlamp near you. Or, plan ahead -- if a particular setting is your subject, and you're just waiting for someone to walk into it, meter the setting ahead of time, and wait.

Also, STUDY available light by studying your results -- keeping a notebook is really smart, because light doesn't change. Notes I made in 1960 still guide me if I see a similar scene. In the end, I think your experience and your judgment will be as good or better than relying entirely on a meter.

The rule of "sunny 16" for shooting without a meter in daylight has similar corollaries for shooting at night, once you get used to it.

Film is cheap, so experiment and bracket your exposures. You might also want to study some of the available light masters. I have always liked Cartier-Bresson, but there are plenty of others, and I can learn from all of them.

-- Robert Swanson (swanny@RampageUSA.com), January 04, 2001.