Atmospheric
Optics
Dutch Still Life Reflections
A photo by Eric Guicherit of �Still Life with Gilt Goblet� by Willem Claesz. Heda.
Note the many window reflections on the metal jug and especially on the partially filled green glass. Are they accurate? Can they be explained?
Heda�s 1635 painting hangs in the Gallery of Honour of Amsterdam�s glorious Rijksmuseum alongside four Vermeers, Rembrandts, works of Hooch, Cuyp, Saenredam and others.
All were products of the 17C Dutch Golden Age, a vibrant time for the new Republic and one of unparalleled prosperity.
Merchants and burghers demanded artworks. Heda�s town of Haarlem had one painter per 500 of population. Painters specialised. Highly staged, figurative still lifes were both popular and a tool to display a painter�s technical mastery.
There are more than nine window images.
A and B are the ones seen in soap bubbles. A is an erect image produced by reflection from the convex surface. B is inverted and formed by the rearwards concave mirror.
Shaking the glass very gently shows that C involves reflection from the water surface. Rays are first focussed by the concave surface in the air and then reflected by the water.
The faint image 'D' involves two reflections from concave surfaces above the water.
There are several fainter 'air side' reflections whose ray paths would probably need mathematical ray tracing to fathom.
The main �water side� image �b� is chromatic. Rays were refracted and colour dispersed at air/glass/water interfaces. Light is reflected and focussed once inside the glass � the ray path is similar to that of a rainbow. The image �c� is elusive. It is near the base of the glass in Heda�s painting and there is every reason to believe its accuracy. It might result from two internal reflections but a water surface reflection is possibly also involved.
Heda�s painting alongside a smaller OPOD glass but of the same approximate shape and curvature.
The window to the left has produced remarkably similar major and minor reflections. The different curvature has shifted them slightly, especially those in the water filled part, but otherwise they are the same.
Heda painted this from life and was an astute observer.
He perhaps cheated just a little because at least three more of his paintings have the same prop with similar reflections!
Rays through air space
C is reflected upwards by the water
Water rays
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