Ringbuoy at Westport (23 Jul 2009)
Posted by Ronan Palliser on July 24th, 2009
One of the biggest challenges with flash photography is learning to use flash in a controlled way.  By controlled I mean in a way where it doesn’t overpower the picture – I suppose even in a way where it is not obvious that flash is being used.  That requires learning how flash works and from that it is possible to learn how its impact on an exposure can be controlled.


My first experience with flash, like every photographer, involved the camera deciding on its own whether or not to fire the flash built into the camera body and in general, me accepting without question the impact of that decision-making process on the final image.  Most of the time, my photographs where the flash fired had bright subjects against a dark, if not black, background, and this wasn’t ideal.

Many years ago I read a book on photography borrowed one summer’s Tuesday afternoon from the Bishopstown mobile library and was somewhat intrigued by the author’s suggestion to (sometimes at least) turn the flash on for outdoor shots during the day, and turn it off for indoor shots in the evening.  This made no sense to me – if it’s daylight outdoors, why do you need flash?  And if it’s not so bright indoors, will the photo not be really dark?

Over time I began to understand that using flash outdoors in daylight was a way of removing some shadows and for instance, a way of taking photographs of people who aren’t squinting at the sun by putting the sun behind them and using flash to keep their faces from being dominated by shadow.  I also began to understand that if light levels were low indoors, setting a slow shutter speed and keeping the camera steady could allow me get some very nice images in ambient light, for the right subject (a still one!).   I also realised though that I could still turn on the flash indoors, but also  play with the shutter speed – and slow it down – to avoid those dark or black backgrounds.

Digital sensors have an even more limited dynamic range – that is in any one scene, there are only so many shades of light and dark that the sensor can handle (typically 256), and where the scene has a wider range of exposures than the 8 stops that this can cover (a stop is a change in the exposure by a factor of 2),  flash can be used to compress the dynamic range of the scene and allow you to expose for highlights and brighten the shadows with flash.

Today’s photograph perhaps isn’t the best illustration of this concept, but it hopefully helps a little to clarify this.  The image was taken at dusk in Westport, Mayo  (in fact, just before I had taken this shot of Croagh Patrick).

Unlike that other image, in this shot I had a foreground element of interest – namely the ringbuoy.  I also had some artificial lights in the background which had a nice visual impact, and which helped to light the building and the cars.  Finally, I had some nice soft light from the dusky sky which was also reflected in the lake.  The challenge was to create an image which represented all these elements as they appeared to my eye.

Let’s suppose I had put the camera on an automatic mode.  It would have metered the scene and thought “oh that looks dark – I’ll turn on the flash and that will solve it”.    How much power would it have applied to the flash?   If I was focusing on the buildings it would have known that they were far away and so turned up the flash full power.  But the ringbuoy, which is much much closer, would have been completely nuked.  If I was focusing on the ringbuoy (as I did in the final shot) it would have known that was close and so only used a smidgen of power.  The buildings would have had no light from the flash and would have stayed relatively dark because the camera would also have used a shutter speed and aperture which were set to expose for the ringbuoy, but not the buildings.

I may have pre-empted these problems would arise if I let the camera do the thinking, and so taken manual control of things (as a general rule, a good idea).  So my next attempt might have been to turn off the flash and set the shutter speed and aperture to keep the buildings and the sky nicely exposed.  Note that, with no independent control over these two elements I was relying on the time of day to ensure that I could keep both of these reasonably well exposed at the same time.  With no flash however, and not alot of light reaching into the recesses of the lifebuoy from that dusky sky, it would be very dark.

In fact, this is what I did – setting a base exposure by exposing for the buildings and the sky – and I  then used the pop up flash on the camera to lift the exposure of the lifebuoy.  Keeping my camera in manual mode, and also taking manual control of the flash power, I could adjust the power until the lifebuoy exposure looked good.

The key was to use subtle tweaks of all the contributors to the final exposure – the shutter speed, aperture, ISO (which I left fixed in this case) and the flash to ensure that the sources of light in the final image – the ambient dusky light, the street lights and the flash – were reasonably well balanced.

It takes a lot of practice to be able to do all this on the fly, and a landscape scene like this is an easy one to practice on, but over the years as I’ve refined my control of these elements and my ability to balance flash and ambient light, I’ve noticed an improvement in the quality of my images which is directly linked to an improvment in the quality and indeed quantity of light that I use to expose for them.   There’s stil more to learn and refine with this area of my photography, but it makes images possible which previously would not have been and so is worth the effort.



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