The above pix illustrate the relatively large scale dark field set-up I use for transillumination of translucent shell specimens previously posted here http://www.photomacrography.net/forum/v ... php?t=9466 ... magnification estimated at 1:4 for the these specimens. Normally the De Vere copystand would enable sufficient height to photograph large specimens but the shells were a little larger than normally tackled - so I had to use a Manfrotto 058 tripod with a horizontal arm just above the copystand column. The copystand has a substantial homemade floorstanding baseboard on which the large darkfield box is supported. Under the curtains there are two tungsten spotlights angled at 45 degrees (ish). The black velvet covered gobos around the subject are made from card stuck onto wooden bases and are essential to avoid light spilling over into the room and reflecting back. I do not use glass to support the subject as it attracts too much dust. Subject support is provided by modular FISSO accessories including clamps and mini- articulated arms. The clamp in the photo is holding just the edge of the shell. The almost non-translucent conch shell in the above link was also photographed using this set-up with the shell supported on a small platform on top of a FISSO pedestal to separate the subject from the background - the transillumination in this instance was sufficient to impart some glow into the subject which was otherwise illuminated with diffused tungsten side lighting plus a reflector. The framework for the darkfield box is also used as an regular subject support as it converts to a table - also placed on the copystand base. When using darkfield lighting the room is blacked out to exclude ambient light. Tungsten spots get very hot so care is needed to avoid the curtains scorching ie do not leave unattended.
I'll post some more pictures of the FISSO accessories soon - they are so useful for lighting and subject support.
Cheers
dunk in Peterborough UK