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Photographing on glass / reflections


#1
  Hello all. Don Rogers posted a tip about using a piece of glass
several inches above your background to create the illusion of
floating your item in the photo. We have used this technique for 

Eliminating reflections from glass that is under a subject is a
matter of controlling the position of the lighting instruments, and
possibly controlling reflections from the art / jewelry piece itself.

Eliminate ALL other lighting sources in the shooting area to
eliminate other stray reflections off the glass. Have a featureless
expanse of wall, paper, fabric etc. below / behind the piece (large
enough to completely fill the “frame” of the scene you see inside the
viewfinder of the camera); if the point where the horizontal and
vertical planes of the backdrop merge will be visible in the
photograph, making this a gentle curve will smooth the transition and
approximate the cyclorama background used in studios. Expect the
transition to still show some, as an overall change of illumination
or color in the backdrop, unless you can get away with seriously
overexposing the backdrop.

If the light sources are all behind the vertical plane of (the
frontmost element of) the camera lens itself, there CAN’T be
reflections off the glass into the camera lens from the sources
themselves - that’s basic physics in this time-space continuum!
(translation: put the lights behind the camera, or just even with
it.) Two sources, one each side of camera, eliminate any shadow of
the camera on the piece, but shadows may still show on the backdrop.
If one light source is of lower wattage than the other, or comes from
further away, the depth of the piece may be shown better. Diffusing
the light sources can help reduce shadows on the piece in much the
same way as a tent / dome that is used for lighting control. Realize
that some degree of shadowing helps in showing depth. Disable the
flash unit on your camera if it is built-in. If you use a "kicker"
from behind the piece, be careful - the light itself may be
out-of-frame but if any spill from it strikes the camera lens some
internal “flying saucers” (aka lens flare) may show in your finished
pictures. Such a light might need to be well off-frame to not see a
reflection of the source in the glass.

It is still possible that light might “bounce” off a shiny piece,
down to the glass, and back up toward the camera. This might be
solved by changing the angle of the light(s), e.g. moving it further
left or right of the camera position, or adding some diffusion to the
light source. Clean the glass scrupulously around the area where your
piece is placed - that’s where your focus will be sharpest. It might
be possible to add some “dulling” coating to the piece being
photographed if it does not alter the appearance significantly in
other ways. Aerosol “dulling spray” is frequently used in studio /
outdoor work on large-scale objects. It may be found at larger art
supply or professional photographer’s supply sources. Be certain it
is the type you can easily remove by simple cleaning and test it on
equivalent materials before ever applying it to a piece you value!
Diffusion gels and media for the light sources themselves may be
found at stage supply sources - ask about them and how close to light
sources they may safely be used. Watch the light sources closely if
you are inexperienced with these, so you will see if such media is
deteriorating, smoldering etc. in front of the lights. Safety first
!!

Spend a lot of time looking through the viewfinder of the camera and
critically examining everything you see, evaluating the color,
shadows, overall composition and looking for those little brilliant
spots of reflection off the glass. This only works if you are using a
"reflex" camera, which shows in the viewfinder the same image that
will be presented to the lens. If you are limited to a less-expensive
camera be aware that what looks OK in the finder may not “look” OK to
the lens, and try to borrow a better camera if at all possible. ( You
rarely get the best results using bargain-bin tools in your other
work, right?) Many digital cameras are non-reflex; those that are
will of course cost more.

Even reflex cameras may not show the exact limits of the frame, and
when your prints are machine-made by automatic processors the entire
negative frame is not printed - some is “cropped” so be aware of that
in your composition. Film is the cheapest element of this process!
Don’t hesitate to shoot multiple exposures of the same thing. Shoot
without changing lens focus or image size, just changing exposure
time or f-opening of the lens, changing lighting intensities, etc.
(Disable any automatic exposure features on your camera so you can
change the settings manually) Keep detailed notes of what you are
changing each time so you can learn what effect each change has on
the finished photograph. Be aware that “bracketing” (shooting
multiple shots, changing only the exposure - both plus and minus what
metering recommends) is probably wasted if you are using print film
and have test rolls processed by the automatic machines, as those
machines are usually set to produce a “best print” , per the
machine’s programming, for widely varying exposure levels. To really
assess the effect of your experimenting, your processing and printing
must be done at a specialty processor and you will want to tell them
that you have bracketed your exposures and that you want all the
prints to be equally exposed and processed. A contact sheet would be
the least expensive way; a single sheet with all your frames in
"thumbnail" format. Using a magnifier you might be able to pick the
best frames to enlarge, but this requires professional experience to
do well! You might at least determine the best exposure times from a
contact sheet (aka proof sheet) and then have one of the automatic
processors produce selected prints so you can use their larger sizes
to look for reflections and shadows.

With slides, all the original slides within a single roll of film
get the same processing so you can check the results of experimenting
by projecting them or laying them out on a light table - and you can
usually have frame numbers printed on the slides to simplify
consulting your notes. Different rolls might get different
processing, and copies may look different - always know your
originals and isolate them for archiving. Once you are confident with
exposure times and setups you can shoot entire rolls of the same
setup and it may be less expensive per-slide than ordering copies,
and each “copy” will be as good as the original - they are ALL
originals!

Well, excuse my verbosity and some straying off-thread. We didn’t
even talk about color !! All your light sources must be the same
type or color-temperature of lamp (bulb), and must use the same (if
any) gel filter in order to later evaluate any color filtration
changes that might be needed.

Above all, allow and spend plenty of time for your photography - or
hire a professional who specializes in photography - and recognize
that if they are good they have probably spent as much time
perfecting their art as you have yours, and deserve compensation for
it.

End of rant, good luck and good shooting.

Michael