Wednesday, 10 October 2012

Exercise 38 Contrast and shadow fill

Following on from the previous exercise on lighting angle, this time I will be considering contrast and shadow fill.  I used a vase as the subject for this shoot and the camera was straight in front, with the light, in this case I chose to use flash, set at ninety degrees to the side and about five feet away from the subject.  After a number of test shots, the flash was set on manual with the zoom at 24mm to spread the light and the intensity set on 1/8 power.

Baseline shots were taken with the naked flash and then with the packing stiffener diffuser in front of it.  After that, a sequence of shots was taken with a large white card opposite the light held at 3 and 1.5 feet from the subject and then with some aluminium foil as the reflector to fill the shadows; the foil was tested with both the shiny and dull sides towards the light and was then crinkled by hand, flattened and used as the reflector with the shiny side towards the vase.  A silver sheet would be expected to reflect more light onto the subject than a white one most of the time, but it worth remembering that a silver card produces direct reflections and has its own restricted family of angles from which reflection can occur.  The reflections from a white card are diffuse and therefore the precise angle in relation to the subject is less critical than for the directly reflecting silver card. 

The initial shot with the naked flash threw the side of the vase away from the light into shadow and brightly lit the flashed side.  The diffuser placed over the flash spread the light into a greater source area and gave more of a ‘wrap around’ effect, lighting the side away from the flash more than was apparent from the non-diffused light source.
Flash - no diffuser, no reflector
Flash - with diffuser, no reflector

The white card held opposite the flash at a distance of three feet from the vase introduced more light into the shaded half of the vase and details in the shadow area started to become apparent.  When the distance between the subject and reflector card was halved the amount of light thrown onto the shaded side increased by four fold (inverse square law) and the light became almost uniform around the vase whilst still retaining some modelling and detail. 
Flash - no diffuser, white reflector at 3 feet
Flash - no diffuser, white reflector at 18 inches

The three shots with the aluminium foil were in many ways the most interesting. The dull surface gave quite an even lighting and softened the details of the vase, whereas the shiny side of the foil generated a really harsh light with the reflector appearing to reflect the light source back in to the surface of the pot.  The details in the pattern on the vase were quite sharply modelled but the image was spoiled by the reflection from the foil itself.   When the foil was crinkled and the shiny side presented as a reflector the shadow fill was much softer than was seen with the flat shiny foil, and the although the reflection of the reflector could be seen, it was quite a pleasing effect to just have the soft hint of a reflection on the vase.
Flash - no diffuser, dull foil reflector
Flash - no diffuser, shiny foil reflector
Flash - no diffuser, crinkled foil reflector

The second sequence of images was photographed in the same order except that they were taken with the diffuser in place in front of the flash.   This reduced the light levels but also clearly softened the reflection due to the diffusion and spreading of the light from an effectively larger source.  The dull side of the foil gave a similar effect to that which it achieved in the absence of the diffuser, with a soft and even light and reasonable modelling of the details.  The shiny foil reflector again gave the harsher detail and the reflection of the reflector was again apparent.  The crinkled foil gave a pleasing effect with good modelling of the detail and good overall level of contrast.
Flash - plus diffuser, white reflector at 3 feet
Flash - plus diffuser, white reflector at 18 inches
Flash - plus diffuser, dull foil reflector
Flash - plus diffuser, shiny foil reflector
Flash - plus diffuser, crinkled foil reflector

I took a final couple of shots with a sheet of black velvet held at three feet or one foot from the vase on the opposite side to the flash to establish what happened when reflected light was significantly reduced.  With the velvet at three feet away from the side of the vase the side away from the light fell significantly back into shadow and the relief of the detail was reduced, but with the velvet held at only one foot from the vase, the light was reduced to=o such a level that the entire image became dull and lifeless, although it is certainly a valid technique if the desire was to have one very bright side and one very dull side in the photograph.
Flash - plus diffuser, black sheet at 18 inches

Flash - plus diffuser, black sheet at 3 feet

Like all the lighting exercises so far I think I have got a lot out of this in terms of understanding the role of contrast and the modelling of detail in an image, and especially in gaining experience of controlling light via the use of reflectors of different types.  I was impressed with the quality of the images that came from the crinkled foil as a reflector as it seemed to me to iron out the worst effects of other approaches whilst accentuating its own benefits.  I have also seen the value to be gained from using diffusion to increase the apparent size of a light source, thereby modifying the impact in the incident light on the subject.  I have done very little indoor lighting and still life photography and this has given me some ideas as to how I can handle parts of the assignment which will form the final assessment of this unit.

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