Monday, July 23, 2012

Formal Portraits with a Flashmeter

Over the weekend I had the opportunity to take portraits for two beautiful families.  I'll discuss the lighting setup as well as the equipment I used, including the Paul C. Buff CyberCommander, which not only controls Paul Buff strobes but also functions as a flashmeter.

My friend asked me to take her daughter's graduation portrait.  It turned out that the official photographer for their school took everyone's photos but omitted the cap.  They wanted to charge extra for another portrait session with the cap.  This irked my friend (rightly so, in my opinion) and she asked if I could instead take her daughter's portrait.

The shot was to be taken indoors in an area about 10 ft. x 10 ft, with a ceiling height of about 8 ft.  Because this was intended to be a formal portrait, I wanted to use a traditional setup with key light, fill light, hair light, and background light:
  • Key light - this is the primary light on the subject and creates the pattern of highlights and shadows.
  • Fill light - this light illuminates the shadows created by the key light.  Depending on its position, it often also contributes to the illumination on the subject.
  • Hair light - this light helps separate the subject from the background and is usually placed above and behind the subject.
  • Background light - illuminates the background.  Adds separation.
I wanted to create a very softly-lit (not edgy) portrait.  For my key, I used a 43-inch umbrellabox / softbrella (it looks like a reflective umbrella but with a diffusion sock, thus somewhat resembling a round softbox) with an SB-800.  The umbrellabox has a more controlled light compared to a shoot-through umbrella, though not as controlled as a beauty dish.  I didn't think we would have a lot of time to shoot, so I positioned the key light for maximum flexibility, about 3 feet above the camera, slightly to camera left, mounting it on a Linco 8310 light stand.

For the fill light, I wanted it to be as soft as possible so as not to create its own shadows.  I chose a 60-inch shoot-through umbrella, positioned slightly to camera right, at about the camera's height.  To illuminate this large light source evenly, I used an AlienBee B1600 monobloc, also mounted on a Linco 8310 light stand.

For the hair light, I used a Nikon SB-800.  To position it above and behind the subject without the stand being seen in the shot, I used a boom stand.  Because the hair light was going to be pointed somewhat toward the camera's direction, I didn't want it to create flare which would reduce the contrast or create ghosting therefore I used a honeycomb grid on the SB-800.

For the background light, I used an old Nikon SB-26, which I just placed on the floor, aimed at the 5 ft x 7 ft popup background.  I varied the intensity between the shots to achieve different effects.

Here's what the setup looked like.

For my lens, I chose a telephoto lens to have a smaller field of view so that I wouldn't capture the area outside the pop-up background, and I could shoot in between the light stands without the stands or umbrellas being in the shot.  I used the Nikkor 70-200 VR with the Nikon D90.

Because this was a formal portrait, I wanted to be very precise with the exposure.  To do that, I used a flashmeter.  I don't have a dedicated flashmeter.  Instead I use the flashmeter function of the Paul C. Buff CyberCommander, the dedicated radio trigger for Paul Buff strobes.

About the CyberCommander
Besides being able to remotely adjust Paul Buff strobes, the CC has several awesome features to make setting up very convenient.  First, it can control up to 16 different light sources.  When you tell the CC which light source(s) you're using (Einstein, X3200, B1600, ABR800 or whatever), it will know the output range (in watt-seconds), flash duration (which varies with power), and color temperature (which in the case of non-Einstein monoblocs, can vary quite a bit with power level).  Each light source can be assigned specific names such as fill light, background light, etc. 

The CC has a built-in flashmeter to allow you to take measurements in 10ths of a stop.  If the setting is not where you want it, you can remotely adjust the power level (and even the modeling light output of any light source) - all while remaining at the subject's position.  Plus you can measure and adjust any single light source or any combination of lights.  There are several remote adjustment options out there, just as there are several flashmeters available, but having the two together makes it extremely convenient to set up lights.

BTW, did I mention you can also use the CC as an incident light meter?  OK, enough about the CC - you'll just have to wait for my review.  Back to our show.

The primary benefit of a flashmeter is the precision of the exposure.  As we know, the camera's reflective meter can be fooled, and when using manual flash, can't be used at all.  Gauging the exposure from the image preview on the LCD screen is convenient but wildly inaccurate.  I often need to adjust exposure in postprocessing when I do that.  A step above that would be using the blinkies, which can help me avoid blowing out highlights (even then sometimes it's inaccurate), but it doesn't necessarily mean that the exposure is correct.  Finally, using the histogram to measure exposure can be misleading.

Besides nailing exposure, another benefit of a flashmeter is that I can set the lighting ratios more precisely.  In portraiture, the ratio of the key light to the fill light is very important and can determine the primary mood of the portrait.  Generally, the stronger the contrast between the intensity of the key and fill, the more dramatic and moody the portrait becomes.

To use the CC's flashmeter function, I just input the ISO and shutter speed I'm using.  I specify the light I'm measuring, aim the flashmeter dome, then press the button to take a measurement.  The flashmeter will indicate the aperture for the given ISO and shutter speed.  As for aiming the dome, there are varying opinions about this.  Some say to point the dome at the light source while others say to point it at the camera.  I'm not about to try to resolve that debate here.  In my case I positioned it at my chin and pointed it at the camera.

First I decided what aperture I wanted to use for the final shot.  I decided on an aperture of f/5.6.  An aperture of f/8 would have given me slightly better sharpness and a deeper depth of field but it would require the speedlights to work harder.  If the aperture had been wider, I was worried that the depth of field would not be enough to keep the entire head in focus, given the long focal lengths I was using.  I thought f/5.6 would be a reasonable compromise.

Having decided the aperture for the shot, I measured the fill light.  Initially, I decided to set it at f/4.0.  That meant that the shadow would be at f/4.0, i.e., one stop less than the subject's highlight at f/5.6, which means the ratio is 2:1.  I then adjusted the key light until my overall measurement (key + fill) was at f/5.6.  BTW, this meant that the key light by itself would have also been at f/4.0.  The highlights of the subject would be illuminated by both the fill light and the key light, bringing their exposure up to f/5.6.

As for the hair light and background light, they weren't linked to the CC, so I just had to adjust them by estimate.


First, I took shots of my friend's daughter.

We had time to take some shots of my friend.

They also asked if their neighbor could take a portrait.  I didn't expect this but I figured we could use the same setup.  After a few shots, I thought a white background would look better, so I just flipped the popup background and increased the intensity of the background light.

Finally, we took a few shots of their dogs.  The larger one posed like a champ.  The poor little one though was really scared of being high up on a chair.

Is having a flashmeter a necessity?  I don't believe so.  There are many situations when using one is not possible (e.g. events), and we do just fine after all.  On the other hand, for setup shots, having a flashmeter makes setting up faster and postprocessing simpler.