Lighting Angles – Mineral Specimen on Black Plastic

Angles make all the difference in lighting; in fact the combination of angles between light source, subject, and camera are what shape and define the subject.  But they also have an effect on the subject’s environment especially when the subject is sitting on something highly reflective…

…such as black Plexiglas™ (a brand of acrylic plastic) which is a common surface upon which to shoot everything from products to food.

In the following two examples, shot last week during a lighting demonstration, the subject is, by an amazingly clever coincidence, sitting on a sheet of black Plexiglas.  Imagine that…  There is also black seamless on the wall behind the set-up.  The shot is so tight on the mineral specimen all that is showing in the shot is the sheet of plexi.  But what is important is what that shiny sheet is reflecting back into the camera.

The subject is a mineral specimen given to me by my old friend and exploring buddy Jeff Forrest in Denver.  This is from one of his own mineral claims in the Colorado Rockies and I am really thrilled to have it sitting on my bookshelves to remind me of him, his wife, Betsy, and our treks into the back country throughout Colorado and Utah “back in the day.”  As the mountain men used to say, giving high praise, Jeff was someone you could “ride the river with.”

The specimen is an interesting piece in itself so it seemed like a perfect subject to demonstrate shooting solid, textured objects for a lighting class.  And it also allowed me to show the effect of changing a critical angle.

The lighting for both of these shots is exactly the same; none of the lights were moved between the shots.  The only change from shot 1 to shot 2 was in the camera angle relative to the subject (and therefore the surface it was sitting on as well).  The lighting for both shots below was created by a 3×4 ft softbox directly overhead and aimed almost straight down.  To that were added two accent lights coming from the rear at about 45-50 degees to each side and about 30 degrees up from the level of the specimen. THis was to rake around and over to enhance texture and show off the different planes of the imbedded crystal.  Another medium softbox provided the fill from close to the camera’s axis and about 10 degrees higher than subject level.  A reflector could have done as well but it was right in the way of the shot.  So four lighting instruments in all were used.

For the first shot the camera was at about 40 degrees above subject level aiming down at the specimen.  The camera was a Canon 5D Mk II mounted on a Cambo Ultima™ “view camera” with the rear “image” standard parallel to the crystal facets to minimize distortion and the front “lens” or “optical” standard tilted for depth of field control.  The lens was a Hasselblad-Zeiss 80mm set to f11.

Shot number 1 with camera in high position.

Shot number 1 with camera in high position.

Here the overhead softbox itself is reflected on the Plexiglas creating a light toned surface even though the plastic is black.  Where the reflection reaches the back of the softbox it turns black providing a two toned environment for the subject.  It is soft because it is way out of focus.  This transitional zone could be moved by moving the softbox forward or backward.

Note the shadow of the specimen in front. The surrounding reflection of the softbox is so light, this appears as a shadow even though actually it is a reflection of the specimen.  See what happens to it below when we move the camera.

For shot number 2, the camera is lowered to about 15 degrees and moved a few degrees sideways to give a slightly different view of the specimen.

Shot two with camera in lower position.

Shot two with camera in lower position.

In this shot, with the change in camera angle, the overhead softbox’s reflection is no longer in the shot leaving the surface black and reflecting only the black seamless behind it and the darkened studio.   Now, against the black reflection (or lack of other items to be reflected) the reflection of the specimen on the shiny Plexiglas really stands out.

The optical and image planes on the Cambo Ultima were modified to accommodate the change in angle and to keep distortion and depth of field loss at a minimum.

There are a couple of side issues that are important to remember.  One is that plastic is incredibly easy to scratch and when stored it develops fine micro scratches that are hard to see UNTIL you look at the photograph where they stand out clearly.  If you are shooting with this kind of material be sure to get a bottle of plastic polish and some good SOFT rags to take out these scratches before you shoot.  I did not do that and it took longer to smooth them out in post-production that it would have taken to just quickly polish the sheet before the shot.

The second issue is debris falling on the surface.  If you want it there, such as crumbs in a food shot, then arrange them properly.  This specimen was “shedding” a fine sand-like pile of white specks and, again, those had to be “spotted” on the file.  I left some in the first shot but “spotted” them out of the second so you can see the difference.


About ndking

Commercial Photographer and Professor of Photography at San Diego City College
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