Saturday, 22 June 2013

Exercise: Softening the light

Bare bulbs of whatever kind, and in this I include Speedlites without any modifiers, create harsh light, which might be the intention, however not in this particular exercise.  Harsh lighting is typified by hard, dramatic shadows, whereas soft light can be seen through soft shadows and lower contrast, creating a more flattering light when used for portraits.  Such diffused light, for example, is great for hiding or disguising facial skin imperfections as well as providing a source of light which starts emulating an outdoor light.

Softening the light is achieved by means of placing some form of diffusion material between the light source and the subject.  The larger this diffuser is and the closer it is to the subject, then the softer the light.

For this exercise I used a small diffuser, referred to as a softbox (60cm x 60cm) which I had purchased on eBay some time ago.  Whilst not comparable to the larger and better softboxes from sources such as Lastolite, it still does the job. This I fitted to a Canon 580EX speedlite.

The exercise suggests that, depending on the subject, the light should be located above the subject.  I considered that this would be suitable for my subject, my Pentacon 6TL camera, which I have had since my college days, 40 years ago!  This is a 6x6 camera taking both 120 and 220 roll film.

I rigged a boom to suspend the light, though somewhat precariously, above the subject, though I had to hold it up once I added the diffuser.  The flash was controlled remotely using a Yongnuo wireless remote control system.  This is manual only, but as I tend to use flash manually, then this is not an issue.

I find that these triggers seem to work without any problems, both indoors and out, as well as at considerable distances.

All my metering is done using a Sekonic flashmate.  I take incident light readings as this removes, in the main, reflectivity, colour and tone issues which would affect reflected light readings.  My camera is set to manual and I find that this combination works really well.

The initial set, with no diffuser is shown in the diagram below.  The Speedlite was set to half power.

The result is below
ISO 100, f/16, 1/125 sec
Very evident in this image is the characteristic harsh shadow, with quite a sharp edge, even though the light was only about 70cm from the subject.  There are distinct highlights, in particular those running along the top of the lens and along the side of the pentaprism.  Also evident is the texture in the black surface covering for the body and prism.  This is a high contrast image.

Adding a diffuser changes the image quite considerably:
ISO 100, f/8, 1/125 sec
The two main differences which are immediately noticeable are the much smaller and diffuse shadow and the lack of sharp highlights which characterised the image without the diffuser.  The texture is still visible, though not as highly defined as in the first shot and overall this has lower contrast.  Adding the diffuser cut the light level by 2 stops.  I could not get a precise match between the two images and felt that the one with 2 stops difference was closest.  Opening up the aperture, also reduced the depth of field and this is also evident in the second shot.  To balance everything, I should have increased the power setting of the flashgun to 3/4 power or even to full power.

This exercise clearly shows the difference between a naked light source and one which has been softened using a diffuser.  How this effect is applied, depends very much on the subject matter and what is wanted as an end result.  

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