• Metal surfaces Metal surfaces


    1. Above two soft boxes are pushed close to the goblet & you catch the reflection of the flash firing giving you the white patches. The black is the trim on the soft box giving you some form. Very little photoshopping used. 2. Above the soft boxes are moved & an angled black strip of paper was laid out in front. The strip reflects into the goblet. It looked unnatural so this was blurred. The use of the diffusers has greatly softened the silver. 3. In this the softboxes were moved back as in 1. but a triangular tent was formed with diffusing screens in front of them. A gap between the back plane and the diffusers creates the black lines left and right. The creation of the black bar in centre was more subtle. It was created by closing the front end of the tent but leaving a small gap for the lens. This was painted out in photoshop.

    Reflective objects

    Smooth polished metal surfaces readily reflect. As we indicated elsewhere we can use the reflective properties of materials to create backgrounds and effects for us. However life gets more difficult if the object itself is highly reflective & curved. There is an artistic trade off here. Do you want to show the reflective nature of the surface or keep the surface free from the light bouncing back directly in the camera? There is no right answer and depends on what you are trying to achieve.

    Here are some examples. They are not finished for product advertising but illustrate the point. The goblet is one of the famous Bristol 600 by the modern silversmith Stuart Devlin. It has a conical form. So the front of the goblet will act like a mirror for anything placed in front on the surface where the foot is sitting.

    We may reflect anything we wish into the goblet but we must be aware it will distort as the plane of the goblet sides are not normal to the surface. Nearly always some post processing is used. I try to minimise this in set ups.

  • Dark glass Dark glass

    The white stripes

    The use of reflected lines of white is seen everywhere in commercial photography, and no doubt other photographers feel like me it is a bit of a cliche.

    The sloppiest example I ever saw was by a really well known perfume brand on a large perfume bottle held by a model in the best magazine one might name (I want work from them so I won't name them!). The cap was reflective but held at a 45 degree angle to the vertical. Yet remarkably in the printed image the reflected line was parallel with the sides of the cap, at odds with the rest of lighting in the picture. It was so obvious that even to someone not used to looking for those features, it was noted that "...the picture looked odd", as it as was expressed to me. We are so used to images and errors within these images due to compositing that glaring inconsistencies can pass us all by. Yet often the consumer will find the image unsatisfactory in some unspecified way. And I say this from a more formal knowledge of hedonisitic testing. Unless intentional, sloppy imagery is not good marketing, it subtly lowers your brand status.

    Here is a dark reflective object: the classic wine bottle shot but not fully prepared for commercial use (I might lift the exposure on the labels a little). There are many ways of lighting this. Near right is a very straightforward approach. Two lights at an oblique angle to the left and right giving a symmetrical reflection. With light directly behind and in front of the bottle to light the label and give a gradient concentrated in the middle.

    To the far right is a variant of this. It's lit on the right shoulder with an overlaid mesh. The label is lit head on and more light is used from behind. It's a bit of fun. You could mix and match the lighting on these two if you wish.

  • Surface measurement Surface measurement

    Reflection and Transmission

    Exactly what makes a surface reflect or transmit light is a complex question. The most important thing when it comes to a photograph is to recognise what the angle of incident light is, the ability of the surface of your subject to reflect light and the relative position of the camera. Metallic surfaces if polished and smooth readily reflect in a coherent manner to produce what is often called a specular reflection. Other materials partially reflect more or less coherently. So mirrored glass for example can produce a slight specular reflection at the surface. This is why a mirror produces a slight double image. The metallic layer reflects, as does the glass surface giving us the double image. This is seen when you operate close up to the glass. You don't see it when you look at yourself in a mirror. If a material scatters the light in many different directions you loose much of the specular reflection and the transparency of the object. The rough surface of a normally smooth reflective material destroys the ability of the surface to reflect an image in a coherent fashion. It also reduces the transmission of light.

    We can investigate the role of scratches on a surface in terms of the light scattered/reflected at a particular wavelength and angle. A Perspex block has been partly scratched and the scattered light has been measured using a Proscan non-contact profiler from Scantron. The flat orange area on the left is the smooth surface. It is not truly smooth but smooth enough to allow the material to appear transparent. To the right of this are the troughs and peaks of a scratched area. The deepest trough is about 3.5microns (in blue). These will stop the material appearing transparent as these are large and rough enough to scatter light in many directions.