Techniques for avoiding reflections please

I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?

Many thanks.


--
AnthonyL

AnthonyL wrote:
I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?

Maybe if you bracketed a few shots and put them together as an HDR?

lid (AnthonyL) wrote:
I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.
....

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.
....

What techniques can I try to get good images?

Reflections are a pain. Generally the problem is that
for each and every light source, there are an entire set
of reflections from any particular glossy surface.
Hence each window will have a reflection, each ceiling
light will too, and so will any other source of light.
If you move the camera to get rid on one reflection, you
are sure to then find another (or half a dozen others).

The trick is to reduce it to just one single point
source of light. For that, a relatively dark room is
idea, so you have a good chance!

Use a single flash, located relatively far away from the
posters, and do not use any kind of reflector or diffuser
on it. That will make it appear as a single spot on any
reflective surface and may allow you to position the
flash and the camera such that there are no reflections
in the image itself (it might only allow you to reduce
their effect though).

You also want the flash to be much brighter than any
other illumination, so setting it for manual at full
power and then using manual exposure on the camera will
help too. And if possible, cover the window and turn
off other lights!

You'll almost certainly have to move around a bit,
taking multiple shots to view the results looking for
positions that result in the least amount of visible
reflection. A modeling light might help a bit, but
it won't be bright enough to see everything, so it's
just a case of shoot and view, shoot and view until you
get it right.

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

On 2008-05-08 04:38:23 -0700, lid (AnthonyL) said:

I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?

Many thanks.



Polarizing filters will not remove specular highlights or reflections
like this. Ideally, you would use screens to block any unwanted light
and you might even use a view camera to offset the camera enough to one
side to eliminate reflections. A simple perspective control lens
*might* be enough, but a view camera would be better. Offsetting the
camera to one side will also keep the reflection of the photographer
out of the picture.

Or you could Photoshop it. Take the image from two different angles, so
the reflections appear in different places on the image. Then simply
erase the unwanted reflections on each layer. See "The WOW! Factor" in
the April/May issue of Photoshop User. Since you are moving the camera
and not the reflections, you will have to use Transform to get the
images to align closely enough that Photoshop can merge them.


--
Waddling Eagle
World Famous Flight Instructor

AnthonyL wrote:
I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?

One thing to try is shooting off axis then straightening it out in
photoshop. You will lose some resolution of course.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman wrote:
AnthonyL wrote:
I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.



Being posters I assume they are actually flat.

This being the case, turn on the tungsetn lamps and take
a whole bunch of pictures from somewhat different places, so
you get good reflectionless images of each part of the poster.
Be sure to use manual settings on the camera so the exposures are
the same. Save as raw. Process the results identically. Ideally
save as 16 bit Tiffs.

Then go into Photoshop and crop out all the reflections. You may
end up with more than one file per exposure. Then put them all
back together with a first rate panorama program like Hugin.

Doug McDonald

I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

Use two flashes at 45 angle to the poster on each side, use fastest sync
speed and a small aperture to reduce reflections from ambient light to
negligible brightness. Some lense become unsharp at smallest aperture so
this is a compromise.

If you have only one flash take one photo with the flash on each side then
blend them together; use manual exposure and manual white balance so the two
photos will match exactly.

Hopefully there are no dust or scratches on the glass.

Use google to check out "copystands". Same principle.

Mmm, you are a bit screwed really. I would try to talk to someone in charge
and try to come up with a deal with them so that they can be removed to
photograph them.


"AnthonyL" wrote in message
...
I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW and
then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image is
too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?

Many thanks.


--
AnthonyL

Ali wrote:
Mmm, you are a bit screwed really. I would try to talk to someone
in charge and try to come up with a deal with them so that they can
be removed to photograph them.


"AnthonyL" wrote in message
...
I'm trying to take some photos of some posters (typically 4ft x
3ft or thereabouts). Some are mounted in glass frames.

The room is quite dark with two small windows in adjacent sides and
also has Tungsten uplights.

I have no problem with the unmounted posters as I can shoot in RAW
and then process with Tungsten white balance.

But I get unwanted reflections with the ones mounted behind glass.
This occurs whether I try using the natural light or the Tungsten
lights in the room. I've tried a polarizing filter but not to good
effect. One problem is that if I use the natural light the image
is too dark for me to see whether there is a reflection in the
viewfinder.

I am not in a position to bring the posters down and put them in a
good location.

What techniques can I try to get good images?


If you can bring lighting into the room, powerful enough shielded
lamps or flash guns may overwhelm the reflections, although quality of
the poster image could suffer.

--
Frank ess

On 5/8/08 12:48 PM, in article q1HUj.27150$zw.11290@trnddc04, "peter"
wrote:

I'm trying to take some photos of some posters (typically 4ft x 3ft or
thereabouts). Some are mounted in glass frames.

Use two flashes at 45 angle to the poster on each side, use fastest sync
speed and a small aperture to reduce reflections from ambient light to
negligible brightness. Some lense become unsharp at smallest aperture so
this is a compromise.

If you have only one flash take one photo with the flash on each side then
blend them together; use manual exposure and manual white balance so the two
photos will match exactly.

Hopefully there are no dust or scratches on the glass.

Use google to check out "copystands". Same principle.


30° would be better.