Available fill light

It says something about People’s Photography that I didn’t even take the book I had brought with me (in the expectation of periods of boredom) out of my bag – and it’s a good book at that (The Girl with the Dragon Tattoo).  Nor did I take a any pictures with the camera I had in the same bag, save for a (largely) failed attempt at time-lapse photography today, and a couple of pictures that were requested by camera-less fellow exhibitors.  But those few requested photos allowed me to play a little bit and experiment with something I had been meaning to try for a while – street portraiture with a single, bare flash.

For a photograph like this, it’s important to remember that a single bare flash doesn’t limit you to a single light source. In fact, for all photography where you use artificial light, you have one more light source than you have artificial light sources, because the available light can almost always be used, if you wish, as a light source in its own right.

In this case my plan was to use the available light as a fill light and that bare flash as a key light.

Sometimes it’s not always possible to easily mix available light and artificial light in a way that allows the available light to play second fiddle as a fill light, because the shutter and aperture required to underexpose the available light may not be flash-friendly.  Here, I was assisted by one important factor – location.  The portrait was taken on the north side of St. Stephen’s Green, and so the whole area was in open shade with no direct sunlight thanks to the trees that border St. Stephen’s Green.

As I play more and more with the use of flash outdoors during the day I’m seeing the benefits of a location that sits in open shade, and going to the north side of a building or a collection of trees is a sure way (in the northern hemisphere, that is) of finding open shade.

So here, my location allowed me to underexpose the available light (necessary as I wanted it to only be a fill light) by over a couple of stops with an ISO/shutter speed/aperture combination of 200, 1/250s, f/11.  I know from previous experience that my flash has no problem working at the distance I was looking at for this picture at that aperture and ISO without it needing to go to full power.  So far so good.

So with the fill light set, initially at least, it was time to add the key light. I was assisted in getting this how I wanted by fellow DCC member, Bonnie, who’s been at the other end of my camera lens in the past.  She was playing the role of voice activated light stand, holding my bare flash (a Nikon SB-800) high at camera right.  I had it zoomed to 105mm to give a tighter beam, and had her point it ever so slightly in front of Andreas, the subject of the photo and my neighbour at the exhibition for the weekend.

Previous experience led me to start at 1/4 power with the flash, which I was setting on the back of the camera via the Nikon CLS system which uses the pop-up flash to trigger the off-camera SB-800.  As it turned out, that was pretty close:

Not bad, but there are a couple of things I don’t like.

Firstly, while the flash exposure is good, the ambient exposure is a bit too dark – I’m on the verge of losing detail at Andreas’ feet and in the railings.  Secondly, the shadow thrown by my bare flash behind Andreas is too harsh.

In fact these are the same problem. The shadow being harsh is because the ambient exposure is too dark. The shadow, by definition, is not being lit by the key light, but is being lit by the fill light, so that fill light exposure dictates how harsh it’ll be.

The fix is quick and easy – open up the aperture from f/11 to f/8, which lifts both the ambient and flash exposures, and compensate for the flash exposure (which is ok as it is) by reducing the flash power from 1/4 to 1/8th power.  That gives me the final frame you see at the top of the post – and you can see how that shadow is much less harsh, and therefore less noticeable.

Speaking of things being quick and easy, I should point out that the whole process from start to finish was less than the time it’s taken you to read this post.  That’s important when shooting on the street, as I was here.  There were people either side waiting to pass as I was getting this shot, so I needed to be quick.

Thinking through how the available light and artificial light were interacting in a logical way allowed me to be quick and gave me an image, which (to my eye at least) is that bit more interesting than an available light shot, where that open shade that was so useful for what I was at here would possibly lead to a much flatter image that probably needed a bit more work in post-processing.