reflection problem. paintings behind glass

[padylyn]

Hi Everybody,
I would greatly appreciate if some of you very experienced people could give me a little advice about taking photos of water colour paintings behind glass.
I seem to have a problem with reflections caused by the glass.
I have been asked to take some photos for a local art group.
Would a polarising filter be any help?
I use a S2IS,

Yours Hopefully,
padylyn:confused:

[cosworth]

Polarizer.

[mcmadkat]

Yes a polariser filter would help.

[cosworth]

The English Empire doesn't rule the world:

http://dictionary.reference.com/browse/polarize

[JustShootin']

Assuming you're not doing this with flash. (And of course you ain't doing this with flash), then a polarizing filter should fix you right up!

Gary

[Jon]

Polarizer alone isn't the universal solution - other key factors are to use indirect and/or off-axis lighting and get a black drop to go over/around you and the camera, with just the lens poking through.

[padylyn]

Thanks very much for your prompt help everybody.
It looks like I will have to try a polariser (or is it polarizer).
In response to Cosworth, I was not expecting a spelling lesson into the bargain. However, as I live in Ireland, not the British Empire, I have Britain on my eastern side and the United States on my western side, so I am quite happy with either spelling. I could spell it in Irish if you wish,
Thanks everybody.

Padylyn

[JustShootin']

Padylyn, sure hope the project goes well for you. And yes, the spelling lesson was rude and uncalled for.

Gary

[mcmadkat]

Well I spell it as it is written on my filter.

[Jim60D]

If the resolution of the combination of your camera's sensor and lens is not as high as you want for the size of the artwork, you can take multiple overlapping photos and photostitch/photomerge them together. If you do this it is best to set the camera to manual so the exposures are identical (do autobracket, though). A non-zoom lens is preferable because prime lenses tend to give less distortion. Macro lenses tend to be the best.

Other things to do are:

If the lens is a Canon, use Canon's free Digital Photo Professional (download and upgrade to latest version). The Lens Aberration Correction feature will minimize distortion and chromatic aberration (and of course set appropriate sharpening etc.) before the merging. For non-Canon lenses, LightRoom 3, DXO and others may have corrections for the lens. This really helps making the photomerged edges of the art work come out straight. This is also helpful if you are photographing the entire artwork in one shot, particularly if you have to use a zoom lens.
To minimize camera motion, use mirror lockup or silent mode 2 plus either a wireless shutter trigger or the self-timer. The wireless or self-timer lets you get out of the way to avoid reflections of you. I once had to re-shoot an entire series because my yellow jacket reflected on the glass!
Autobracket the exposures since this adds minimal time compared to your set-up time.
Black cloth (as mentioned by previous poster) and a darkened room are needed to eliminate reflections that are essentially straight back to the camera. A polarizing filter can not help with these because only reflections at an angle off the glass are polarized.
Get the optical axis of the lens exactly perpendicular to the artwork. This takes some care but will minimize distortion and maximize sharpness. Start by putting the center of the artwork at exactly the same distance from the floor as the center of the lens (I assume you are using a tripod). Check the viewfinder (or use LiveView) to ensure the edges of your image are parallel to the edges of the artwork. LiveView at 10X is helpful to check focus at center vs. corners.
Finally, one method I've used to get the lens axis perpendicular to the artwork uses the reflection of a small bright flashlight. First put the flashlight exactly at the side of the lens, directed at the artwork. Adjust the camera vertical tilt so that the flashlight’s reflection is exactly at the horizontal mid-line of the image (displaying the center autofocus point provides a good reference point). Then put the flashlight at the exact top of the lens and similarly adjust for the vertical mid-line. A panorama tripod head helps here so as to not alter the vertical adjustment you just did. Now you have the lens axis perpendicular to the glass covering the artwork.