Photo Blog 020 – Experimenting with flash, some examples

Good morrow kind sirs,

I decided to give Sonia a break from modelling for me last night by giving some self portraits a go as she went off and did her thing taking some twilight shots of the Opera House and city skyline. I felt a little dorky setting up my tripod and light stand and posing for myself whilst all the tourists passed by – I got over the whole self-consciousness thing pretty sharpish though mostly by harnessing my powers of ignoring.

I think I got the lighting and shadows on my face just right in this shot, giving enough of an angle to de-fatten my face (you’ll see some not-so-good examples in a minute). Underexposing the background a couple of stops resulted ina really nice deep warm glow just behind the silhouetted city buildings and overall I thought this was my best effort.

Going through the bunch of photo’s I came back with I hit across a couple of examples which sprang the idea to make this into a bit of a tips/how-i-did-it post. I’m still very much learning all this stuff so I may seem a little naive still, but I just wanted to excercise a couple of main principles of flash photography in this post. The first point of which being that the shutter speed is the key in determining your ambient exposure.

The flow I have been using since trying out the strobist techniques has been to manually dial in my exposure a couple of stops below the “correct” exposure. Starting with the shutter speed at 1/200 sec (my camera can synch with the off-camera flashes at 1/250 max, so I’m giving myself some room) I then set my ISO to around 400 to let me go up or down later if needs be. Then finally I place my aperture at around f5.6 to again give myself room to move up or down. If those settings give me a scene which is too light, I start moving my aperture towards the higher numbers to darken it to my liking. Alternatively if it is too dark, I go the other way.

The above shot is an example of getting to my starting point before introducing the flash.

Next, it’s just a matter of placing my off-camera flash in a position that gives depth and dimension to the subject (me!). Generally for this kind of shot high and to one side will fit the bill nicely. I don’t bother with light meters or working this stuff all out properly, it took me a grand total of two test shots to dial in the flash to a brightness that gave me the result I was looking for. In this case, 1/16th power was all it needed.

As you can see, the background stays pretty much identical as I have not changed any settings in camera but the introduction of the flash has brought me up to a good exposure nicely. As mentioned above, the shadows aren’t being cast in as flattering a way as the first shot in this post – with me being turned slightly more towards the flash I am adding more light to the left side of my face and giving it a more fuller appearance. However, we’ll brush over the inadequacies of the model for the sake of a good technical example…

Now that I have got my flash set at 1/16th power and my aperture in this case, fixed at f9.0, I know that whatever I do to the shutter speed (to adjust the ambient background exposure) I will always remain at the same exposure myself. Shooting at twilight this becomes a very important thing to know as the light changes very quickly as the sun disappears off below the horizon. By the time I took the next shot, I was shooting with a shutter speed of 1.3 seconds to achieve a similarly exposed background…

The settings for this shot were: F9.0, ISO400, 1.3 secs – flash on 1/16th power from top left. As mentioned, the difference being the shutter speed. Because the aperture and flash were still set the same as before, I knew I would be exposed exactly as before.

For a bit of a test I decided to really push the example and change my shutter to 6 seconds. This I hoped would bring the background up a couple of stops but keep me looking the same…

Here is the result…

And hey presto! Arguably I do appear ever so slightly brighter in this longer exposure and I did say that my exposure would stay the same, but I put this down to there being a wee bit of ambient light coming into play as there are street lamps lined up along the path which I will suppose cast enough light on me to lighten some of the shadows over the 6 second exposure, but hopefully you get the point.

Well, I think I’ve covered what I was trying to express… Just a few examples of how the shutter speed, aperture and flash power all affect a shot… (I’m not trying to re-invent the wheel here, head over to strobist.com if you want to learn this stuff properly lol!)

Thanks for stopping by, and until next time – happy snapping!