Trust Your Light Meter

Late November, I finally bought a hand-held light meter: the Sekonic L-358 Flash Master. The biggest reason I did this is that I was getting more and more into studio-style portrait photography and, in that realm, the hand-held meter can be really, really useful... But only if you trust it!

So, I did two portrait shooting sessions in December. One was with my neices and nephews, a now annual event where I feed them lots of candy, take Christmas themed photos, and then send them back with their parents. There are a couple of upsides to doing this: I get the photos I want, my siblings save money on studio shots. At any rate, this shoot was my first experience with the Sekonic. In order to use the Sekonic, I needed to make use of the PC sync cable option on it because I'm using Cactus V4 radio triggers and the Sekonic option is for Pocket Wizard, but this worked perfectly fine. You just simply connect the Cactus transmitter to the light meter using a PC cable (a short one is fine, just let it dangle) and you're in business.

At any rate, I did a few test shots based on the settings I'd defined in the meter and adjusted the options on the camera accordingly. After each shot, I chimped the result and, for whatever reason, decided that it was too bright... Let me tell you, the display on the back of the Pentax K-5 is very good, but not really good enough to use as a true assessment of the final result, especially when shooting raw. So, thinking that I was overexposing, I adjusted the settings on my camera with the following result:


Whoop! That's a little dark to say the least. Now, fortunately, I was thinking I was overexposed, so I didn't blow out highlights and I could recover the images thanks to the incredible dynamic range of the K-5 and got this back out:


So, a week later I went over to a friends house with a lot of my gear in order to take a number of photos for her, including a re-do on school shots that she was unhappy with. This time I decided to resist any urge whatsoever to distrust the light meter and accepted its readings. The result was:


Much more accurate exposure, in fact it's spot on. I still need to work on some light positioning to better fill in some of the shadows, but I nailed the position for Leah's glasses (the secret is move the light high as angle of reflection equals angle of incidence).

Now, some of you might wonder why I'd bother to use that light meter instead of the spot meter in the camera. Well, the basic reason is that with spot metering the subject that is metered is read as 18% gray and that can alter the highs and lows if the subject isn't actually 18% gray. There are ways to overcome this and increasing the area that is being read helps that (hence the various metering modes on the camera), but it's not always what you're looking for. The net effect is that if you meter something shiny and don't account for that in the result, then less shiny things will come out very dark. If you meter something very dark and don't account for that, shiny things will be blown out.

Incident metering, on the other hand, simply measures the amount of light that is falling on the subject and doesn't account for the subject at all. The upside to this is that dark things are dark, shiny things are shiny, and the overall result more likely reflects the actual scene. The other big advantage is that I can meter the strobes being used, something spot metering from your camera can't do unless it takes a picture. At any rate, one of my favourite sites, Cambridge in Colour, has a good writeup on camera metering that is worth reading.

Of course, nothing is perfect, you still have to use judgement, but the one lesson I really did learn was: trust your light meter.

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