Backlit Macro Project

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About This Project

I have been planning this project for a long time.  The idea is pretty simple.  To be able to shoot a backlit subject with a macro lens you either have to wait for the sun to be juuust right or you need a light box that can illuminate a subject from beneath that subject.

Light boxes are available for sale of course but part of the fun of a project like this is to build the equipment you need rather than buying it off the shelf.  The key to a light box is even illumination across as much of the imaging area as possible.  That's harder than you might think.  Any light source within the light box will be more concentrated nearer the light source than away from it.  So the key is to reflect that light off the interior of the light box to even out the light.  For my version I used 4 florescent fixtures angled to the opposite corners to reflect the light off of two surfaces.  The interior of the light box is flat white and there are no sharp corners.  There is also an additional diffuser, a white piece of plexi-glass followed by the top plexi-glass that further diffuses the light. 

For most applications this even illumination is not that critical.  But I had a secondary goal with this light box.  Not only did I want to use it for this project but also as an evenly illuminated light source for flat frame normalization of frames in my astrophotography.  I determined that this light box, which is 20" x 20" has an adequately even illumination for a telescope of up to 18" of aperture.