Wednesday, 21 September 2011

Light:Project - Photographic lighting - contrast and shadow fill

Exercise: contrast and shadow fill

Aim:  the aim of this exercise is to use different types of reflector to create shadow fill and to note the difference created by different distances and surfaces.

Approach and results: I first tried this exercise with the cactus that I used in previous exercises but the results were not so obvious.  For a bigger subject I think I needed a bigger reflector.  the snails are useful to compare the effects on colour.  The results were quite subtle in some instances but none the less made a difference.  As I was quite close I used F16 throughout in order to get sufficient depth of field.  Some of the differences will also come from the fact that I was hand holding the reflector so the position is not identical on each image.

The first shot was taken with no diffuser.  The light is harsh and the table top has a light sheen on it.  The second shot was with a 60cm softbox.  This has reduced the exposure, strenghtening the colours but there is a lot of shadow.  The third shot uses a white card reflector on the opposite side to the flash and a similar distance away (1m approx).  This had very little effect at all.  You could say that it very slightly lightened the shadows but it is marginal.  The light reaching the reflector is 4 times less than the light reaching the subject as the reflector is twice as far away.  This is before you take into account the distance that the light is reflected back (a further 1m).  It is therefore not surprising that the light reflected back has little impact.  The forth shot brings the reflector twice as close and there is a noticable difference.  The green and red shells are more evenly lit, the green snail body is more visible and the table top detail is clearer and less shadowed.

Shots 5,6 and 7 use foil as the reflective surface.  Firstly using the dull side, then the shiny side and finally a crumpled shiny side.  The foil is more reflective than the card and lightens the shadows still further.  It is not until the foil is used that the face of the red becomes lit at all.  The shiny side of the foil is by far the most effective as a reflector.  There is clearly detailed relief on the side of the green snail.  Crumpling it makes it slightly more diffuse and less directional, brighter than the dull side but softer.

Learning points:
Up until now I have always used a piece of white card when I needed to reflect light apart from one occasion where I used a silver tray to create a spotlight.  Changing the type of reflector can have a subtle but significant effect. The results with the foil shiny side out and crumpled are the most impressive as it managed to reflect more light but keep it diffuse.
A reflector needs to be qiute close to be effective because of the light fall-off. 

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