I'm trying to sell a picture of a piece of artwork for charity, and I'd like to photograph it. It's in a glass frame with lots of glare. Any ideas of what I can to to photograph it to look the absolute best? Thanks!
When it comes to glass it's all about lighting direction.
You want to make sure that when you look at the picture through the camera neither the reflection of the lightsource or anything lit by your lightsource is visible.
Hold up, I'll draw a diagram:
Glass and other shiny objects reflect light back in one direction (like a ball bouncing off a wall). The painting, which is diffuse reflects some light this way, and reflects some light back in every direction.
In the setup above, the light from a directional source hits the glass and carries on, missing the camera, thus the glass isn't visible! The same light hits the painting and some of it does get reflected into the camera so the painting does show up.
The important thing is to use a directional source, as it's possible for light from your lightsource to bounce of a white wall, and hit the glass at an angle that does go down the lens, and this shows up as flare.
This often happens when you have a white wall behind the camera, as in the above example.
The moral of the story is to make sure you can't see the reflection of the lightsource in the glass when stood behind the camera, and try to limit what the light hits (ideally it should hit nothing but the painting). You can make any lightsource directional by placing opaque objects around it to block the light in certain directions.
The key to photographing this is about the angle of light(s) used to illuminate the surface of the art. It's all about angles and reflection and it's probably easier to illustrate this (pardon my poor Coreldraw skills).
The dotted lines connecting the camera show the angles of direct reflection, so if the lighting is inside those lines, the glare will be very evident. What you need is diffuse reflection and to get that, you need to have the light outside those lines, to one side, but preferrably both.
Sorry, the reflection lines in the far sides of the camera are a bit faint...
I happen to frequently photograph artwork, including framed and with glass.
If possible, do this in a room that has black walls and no windows. If such room is not accesible, wich is my case, I use a black backdrop BEHIND the camera. This helps a lot against unwanted reflections. Also, as the other answers point out, place the lights a 45 degree or more relative to the line from the lens to the center of the artwork. It means, 2 simetrical lamps, one at each side and at the same distance from the front and from the sides of the artwork.
For example, if dealing with a 1 meter wide painting, lamps would be rougly 1 meter in front of the painting and 1 meter away from the edge of the painting. Lamp heads would be at the height of the horizontal centerline of the piece. Partly close the barn doors to limit light output so it falls only on the painting.
I Use a tripod and fire the camera using a computer and a usb cable. This is to avoid unwanted movement of the camera and to avoid my own reflection on the glass. If necesary, cover the camera or tripod's shiny spots with something matt black. (a cloth may be enough). Also remove/cover any shiny objects in front of the artwork. If the computer or remote shutter is not available use the temporizer. If that is not available either, then wear dull, black clothing, including a skull cap or simlar and keep the face behind the camera.
When framing, the lens axis should point perdendicular to the center of the artwork (specially if it's rectangular) to avoid perspective distortion. (It's correctable in post, but preferable not having to...)