Re: Is glare the same as reflections?

"Burgerman" <burgerman@xxxxxxxxxxxx> wrote in message
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<ronviers@xxxxxxxxx> wrote in message
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Will a polarizing filter help in the photographing of a painting
behind glass?

Does anyone have any tips for how best to shoot a painting that cannot
be removed from its glass frame?
Using a Canon 40d with kit lens.

Thanks,
Ron


Polarising filters can remove reflections only in the direction the light
is polarised in.

So a light on a single bit of glass - yes quite possibly depending on how
its lit...
The reflections off a multitude of surfaces at different angles or one
flat surface with different reflections from several sources - no.

Imagine the filter is a mass of slots that are horizontal (at the moment)
and you are shooting a flat calm swiming pool. All the light reflected
off the water is horizontally polarised so the filter lets all the
reflections through. Turn the filter 90 degrees and they are in the wrong
plane so now the filter blocks these horizontal polarized reflections and
you can see the bottom of the pool.

A couple of years ago I photographed a 60 year old painting done on the
reverse side of a *** of glass (so that the detail or top layers of the
image had been applied to the glass first!) which had been cracked in
several places so that I could retouch it in Photoshop and get some prints
made. I used a Canon 350D and experimented with various light sources with
and without a polarising filter but without much success. Eventually I
solved the problem of reflections, including that of the camera and tripod
itself, by tacking an old bed *** to the ceiling, cutting a hole in it to
accommodate the lens and used natural lighting. I tried firing the on camera
flash diffused behind the *** but it didn't make much difference.

I used the 18-55mm kit lens and was pleasantly surprised by the results, as
was my friend's father who did the painting all those years ago when he was
a teenager. It's now been re-printed several times up to approximately
original size and given out as a Christmas presents to his friends and
family.

When framing the image in the viewfinder I zoomed in as close to the inner
edge of the frame of the painting as possible but did not include it as this
would highlight any curvature in the horizontals and verticals which are
more noticeable at the edges of the frame and which were not needed in the
finished image in any case.

HTH

Garry




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