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Avoiding flash glare (was Oz displays/museums)



On 11-7-97, Steve, the Armadillo with the Mask <armadilo@daft.com> wrote:

> Ooops..yeah, sorry 'bout leaving out the Hypsi(which I did see). I was
> replaying things from what I took pictures of and remember skipping the
> Hypsilophodon photowise 'cause it was behind glass and I'm not Steve
> Parrish by any means when it comes to photo taking and avoiding the flash
> glare on the case, etc.

OK, here's what you do.  Avoid aiming your camera/flash in a line
perpendicular to the glass case.  This is most important.  If you angle
yourself at, say, 30 to 60 degrees to the glass, then you will at least
avoid bouncing the flash right back into your camera lens.  Your other
concern then becomes: where is the light bouncing off the glass going,
because you will potentially illuminate other objects or people which could
show up as unintended ghostly reflections on the glass.  "The angle of
incidence equals the angle of reflection," if you enjoy thinking in such
terms.  But with luck these reflected items would be out of focus; or
farther away than your intended subject, so that they do not receive the
maximum amount of bounce light (and, hence, would show up darker in the
reflection).

Then again, some <ambitious> people use an auxiliary flash unit which is
held or mounted at some distance from the camera and then angled so as not
to cause reflections the way a camera-mounted unit would.  (Variations on
this concept are popular with professional portrait photographers who seek
to avoid "red eye").  But your flash must be carefully aimed or it won't
evenly illuminate your subject.  And, of course, you could reflect yourself
in the glass if the flash illuminates you.     

If you are not using a flash, you can feel free to shoot perpendicular to
the glass as long as your own reflection is not bright.  But if you
experience undesirable reflections (of something other than <you>)
resulting from the available lighting, you may  consider the use of a
polarizing filter on the camera, which should be adjusted while you view
the subject through the lens for maximum effect.  The polarizing filter
will cut down the light reaching the film, so your film speed and
depth-of-field are considerations when you use this accessory.  A
polarizing filter is also useful whenever you wish to capture richer colors
at the expense of the dimensional relief of a subject under location
lighting conditions.  It works wonders on autumn leaves, skies, and water
scenes.  But it cannot cut out reflected glare emanating from every
direction (such as that from a camera-mounted flash unit), and will do
nothing to eliminate reflections on mirrors or chrome.  Polarizing filters
work just like polarizing sunglasses, so you can look through one of the
polarizers of a pair of sunglasses as you rotate it around its center to
get some idea of the effect.  When shooting by available light (especially
in those dusty old museums), you may wish to consider using 1600 ASA film
for your documentary work, but, of course, you may not find the resulting
images satisfactory, as the prints will be grainy.  It depends on what
you're after. 

Or you just go hire Louie Psihoyos...

Ralph Miller III <gbabcock@best.com>