Photographic bight shiny objects?

____ wrote:
In article ,
Wolfgang Weisselberg wrote:


Polarizers only work on non-metallic reflecting surfaces,
which silver isn't.

I disagree.

First, reflections from metal surfaces are not polarized,
and polarizing filter will *not* have any effect.

However, just because the item is made from silver does
not mean the reflection is from a metalic surface. If
it has _any_ kind of coating on it, the polarizing
filter will have some effect. Hence if the surface has
been polished, for example...

And that is exactly what the OP needs to consider, if a
polarizing filter is to be used. Almost anything that
provides a "clear" coat will also allow the filter to
work.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

On Feb 12, 8:21 pm, Wolfgang Weisselberg
wrote:
David J. Littleboy wrote:

"Roy Smith" wrote:
I've got to shoot some sailing trophies -- highly polished silver with
lettering engraved on them. The lettering needs to be readable in the
photos.
Any non-obvious tricks to get good lighting without lots of glare and
reflections off the polished surfaces?
Try a polarizer. Don't expect wonders but it might reduce some of the
reflections somewhat.

Polarizers only work on non-metallic reflecting surfaces,
which silver isn't.

-Wolfgang

It is true that metallic surfaces cause *little* polarisation... But
components of the light that falls on the metallic surface may
*already* be polarised. That is why the polariser may still have a
significant effect. However, to be useful, it would be best to
combine a polariser on the lens with a polarised screen over the light
source/s as well...

"Floyd L. Davidson" wrote in message
...
____ wrote:
In article ,
Wolfgang Weisselberg wrote:


Polarizers only work on non-metallic reflecting surfaces,
which silver isn't.

I disagree.

First, reflections from metal surfaces are not polarized,
and polarizing filter will *not* have any effect.

However, just because the item is made from silver does
not mean the reflection is from a metalic surface. If
it has _any_ kind of coating on it, the polarizing
filter will have some effect. Hence if the surface has
been polished, for example...

And that is exactly what the OP needs to consider, if a
polarizing filter is to be used. Almost anything that
provides a "clear" coat will also allow the filter to
work.

One option that will help is to polarize the light source(s) and then put a
polarizer on the camera at 90 degrees to the angle of polarization of the
lights. Another is to use a light tent or big softbox to minimize point
reflections and objects reflected in the polished plate.

Toby

Toby

Mike Coon mjcoon@ wrote:
Wolfgang Weisselberg wrote:
Polarizers only work on non-metallic reflecting surfaces,
which silver isn't.

I happen to have a silver-plated trophy and a polariser to hand; it works
for me!

Lightsource? Unpolarized?
Is there any type of coating on the trophy?

Can you cite a contrary scientific source, please?

Any physics book dealing with reflection ans polarisation.

Can you cite any scientific source for your position, please?

-Wolfgang

Wolfgang Weisselberg wrote:
Mike Coon mjcoon@ wrote:
Wolfgang Weisselberg wrote:
Polarizers only work on non-metallic reflecting surfaces,
which silver isn't.

I happen to have a silver-plated trophy and a polariser to hand; it
works for me!

Lightsource? Unpolarized?
Is there any type of coating on the trophy?

Can you cite a contrary scientific source, please?

Any physics book dealing with reflection ans polarisation.

Can you cite any scientific source for your position, please?

-Wolfgang

My position was mere observation. Admittedly my trophy is a bit tarnished,
though most reflection is evidently from the silver since tarrnish is black,
but all light sources seem to be equivalent.

I shall fetch my undergraduate optics textbook and look it up (Brewster
angle I can remember!)...

Mike.
--
If reply address = connectfee, add an r because it is free not fee.

Floyd L. Davidson wrote:
Roy Smith wrote:
I've got to shoot some sailing trophies -- highly polished silver with
lettering engraved on them. The lettering needs to be readable in the
photos.

Any non-obvious tricks to get good lighting without lots of glare and
reflections off the polished surfaces?

A ring light might help, if the surface with the
lettering is flat. Tilt the lettered surface so that
reflections from the ring light are not straight back at
the camera. However, with curved surfaces there isn't
much hope of avoiding at least some glare from the
light.

In that case, consider multiple lights, and also a
"light box" or "light tent". The trick with multiple
lights is to position them such that the glare does not
detract from the object. Generally two lights will do,
and one of those will be at very close to perpendicular
to the axis of the lense. Placement of the other
depends on the glare. With a light box/tent, the idea
is to get diffuse light from every direction, thus
reducing the contrast of the glare.

I prefer a light box, simply because they are so easy to
construct from cardboard boxes. If your trophies are 4
feet tall though, it might be a problem... but there
are solutions for that too.

Do a google search on "light-box glare photography", and
it will provide several examples.

However, in a quick review I didn't see any that showed
the particular construction that I prefer. So I've
resurrected something I had on my web page a couple
years ago for a short time just for one individual to
look at. I dumped about half of it (it was actually to
compare several different alternatives to expensive
"macro lenses", and showed several compartive images),
and have just left the comparison between a ring light
and a light box, plus some images of the light box
showing how it works.

http://web.newsguy.com/floyd_davidson/dime/

Floyd, can you explain the difference? I don't understand. The dime
looks awful and flat with the ring light, maybe too contrasty with the
light box, the clippers look nice and even with the ring light, a little
to harsh with the light box.

Does the light box provide a similar effect to a light tent?

Paul Furman wrote:
Floyd L. Davidson wrote:
....
Do a google search on "light-box glare photography",
and
it will provide several examples.
However, in a quick review I didn't see any that showed
the particular construction that I prefer. So I've
resurrected something I had on my web page a couple
years ago for a short time just for one individual to
look at. I dumped about half of it (it was actually to
compare several different alternatives to expensive
"macro lenses", and showed several compartive images),
and have just left the comparison between a ring light
and a light box, plus some images of the light box
showing how it works.
http://web.newsguy.com/floyd_davidson/dime/

Floyd, can you explain the difference? I don't understand. The dime
looks awful and flat with the ring light, maybe too contrasty with the
light box,

I think you've reversed them? The light box is flat, the
ring light has contrast.

the clippers look nice and even with the ring light, a little
to harsh with the light box.

The clippers are interesting. A cut glass object or a
clear glass figurine with smooth contours would perhaps
show the difference better.

The ring light shows reflections from one direction. It
isn't as distinct as a point source light would be
though. With a longer focal length and a greater
working distance that effect would be more emphasized.

The light box shows equal reflections from every
direction, which simply makes some surfaces brighter and
reduces the contrast. The likelihood of a black
reflection from the camera can be reduced by using a
longer focal length to get more distance.

Does the light box provide a similar effect to a light tent?

A light box and a light tent accomplish almost the exact
same thing; hence, generally they can be considered to
have the same effect. In practice though, the actual
construction of each will cause differences, and some
characteristics are more likely to be exaggerated with
the box, while others will be with the tent.

In either case the essential concept is to diffuse the
source of the light in such a way that an object is
illuminated equally from every possible direction. That
is why the picture of the dime taken with the light box
is so horribly _flat_! It's hard to see any of the
surface contours, and there simply are no shadows. On
the other hand, notice how the edges of the engraving
are all white regardless of the direction.

The ring light is a different beast, as the light is not
diffused, but it does come equally from all sides in
relationship to the center of the lense. Hence shadows
are a function of the surface of the object, not the
direction of the light. And contrast is high (though
not quite like it would be from a point light source).

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

"Rita Berkowitz" wrote:
Floyd L. Davidson wrote:

In either case the essential concept is to diffuse the
source of the light in such a way that an object is
illuminated equally from every possible direction. That
is why the picture of the dime taken with the light box
is so horribly _flat_! It's hard to see any of the
surface contours, and there simply are no shadows. On
the other hand, notice how the edges of the engraving
are all white regardless of the direction.

NONSENSE!

Had you slightly clanged the position of the dime to the lens you would have
had a beautiful picture that has life. Stop blaming the lightbox because
many people have demonstrated that it is an effective way of getting their
items to pop.

Poor "Rita".

Just in case it isn't obvious, that particular light
box, as demonstrated by the photograph of the dime, is
just about as good as it gets for soft lighting of small
objects. (I made it originally to photograph some old
ivory carvings that were 2-3 inches long. The
particular design is fairly commonly used to photograph
archaeological artifacts when absolutely flat light is
desired.))

But it could have been even better! It's only about 6
or 7 inches deep, and that is just about the same size
as the front opening that the camera looks into. If the
box had been made 12 inches deep, or more, it would
allow a small object that is positioned the same 3-4
inches distance from the back of the box to receive even
more light from reflections off the box area to the
front of the object. That would probably reduce the
contast between the front and the edges of the
engraving.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Rita Berkowitz wrote:

From what I see there I don't know what the hell he's doing. I'm not even
sure if he knows what he's doing since all these examples look terrible.
There's no way you can get that level of dullness from either light source
he is using.

"The images were taken with a Nikon D2x ..."

-Wolfgang

PS: Yes, Rita-baiting ain't fair.

"Rita Berkowitz" wrote:
Floyd L. Davidson wrote:

In either case the essential concept is to diffuse the
source of the light in such a way that an object is
illuminated equally from every possible direction. That
is why the picture of the dime taken with the light box
is so horribly _flat_! It's hard to see any of the
surface contours, and there simply are no shadows. On
the other hand, notice how the edges of the engraving
are all white regardless of the direction.

NONSENSE!

Had you slightly clanged the position of the dime to the lens you
would have had a beautiful picture that has life. Stop blaming the
lightbox because many people have demonstrated that it is an
effective way of getting their items to pop.

Poor "Rita".

Just in case it isn't obvious, that particular light
box, as demonstrated by the photograph of the dime, is
just about as good as it gets for soft lighting of small
objects. (I made it originally to photograph some old
ivory carvings that were 2-3 inches long. The
particular design is fairly commonly used to photograph
archaeological artifacts when absolutely flat light is
desired.))

But it could have been even better! It's only about 6
or 7 inches deep, and that is just about the same size
as the front opening that the camera looks into. If the
box had been made 12 inches deep, or more, it would
allow a small object that is positioned the same 3-4
inches distance from the back of the box to receive even
more light from reflections off the box area to the
front of the object. That would probably reduce the
contast between the front and the edges of the
engraving.

That still doesn't explain why that image looks so terrible when everyone
else is getting much better images when using soft lighting techniques.

Poor "Rita". Look up what "soft lighting" is.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)