Great photos can be crafted in each of these situation, but you must be prepared to meet the "glass challenge;" reflection and focus.
Reflections on glass can be a photographer's bane, but sometimes a friend. One of the biggest problems with reflections is our brain works so well that sometimes we don't even notice small ones, but the camera doesn't miss a thing. As photographers, when working through glass, we must make ourselves aware of these reflections, which sometimes can even be us, or our clothing.
When shooting through glass, some cameras have trouble focusing on the subject and attempt to focus on the reflections on the glass. This must be overcome.
In the above photograph of a tailor shop in the Olde City area of Center-City Philadelphia, I wanted to capture the whimsy of the window painting of a tailor at a sewing machine. That required me to focus at the window, and use a midrange aperture (f8) to create significant depth of field to keep the shop in focus behind the window. Fortunately, when I came by the shop, the sun was behind the buildings across the street, so sun and building reflection was at a minimum, however, I had to wait for traffic to move past the shop to eliminate their reflection.
- If you can, don't use a flash. That will immediately eliminate its self-reflection. When you must use a flash, do not direct its light straight on or you will get a photo of the flash of light it produces. Move the flash head to an angle so the flash's reflected light bounces off the glass at an angle, not directly back into the camera's lens. If you're taking a photo through a display case, and have an "off camera" flash, try using the flash from above the case. Using a "fast lens," a lens which can open its aperture very wide, can mitigate the need for flash use.
- Perhaps the easiest was to eliminate reflections and focus problems is to hold the camera as close to the glass as possible to avoid glare and reflections. If you can, use a rubber lens hood, if you have a DSLR, to seal out light, or if its a point and shoot camera, use your hands at the side of the camera to do the same. This also has the benefit of eliminating problems of dirty glass as you will be focusing past the dirt on the subject behind the glass. If you need a wide view, use a wide angle prime or zoom lens. This is a great way to photograph at an aquarium.
- Sometimes you can't get very close to the glass, since you want a wider view of the subject behind it. If the light is from a single source, such as often found in a museum, or even multiple sources, stand to the side of the subject to minimize the reflections from the light and eliminate your reflection.
- You can use a circular polarizing filter almost anytime you are shooting through glass, or water for that matter. Circular polarizers are necessary with today's through the lens metering (TTL) and auto-focus cameras. Linear polarizers, though more effective, generally render TTL and auto-focus ineffective.
- If you're shooting through a window of a moving bus, or a helicopter there are several things to do. Use a fast shutter speed. That will help you negate the movement of the bus. Consider manually pre-focusing your lens, or if your camera has the capability, use continuous focusing. Try setting your aperture at mid-range which will lengthen the depth of field, making up for focusing inaccuracy. If your DSLR lens has vibration reduction (VR), use it, especially if it has active VR. If your point and shoot camera has image stabilization, use it. Get as close to the window as possible, without touching it, to eliminate glare and reflection from inside the bus. Try a trick suggested to me. Use the rubber end of a light weight toilet plunger. Cut a hole in it for your lens and use it to block the light from inside, with the lens close to the window.
Some people suggest the use of a circular polarizer when shooting through the windows of a helicopter or bus. It definitely can help you lessen or eliminate the refections on the window glass, or helicopter's Plexiglas, but if you've ever worn polarized sunglasses while in these vehicles you already know that it will accentuate the stress marks in the Plexiglas or the spots in the safety glass. Personally, I wouldn't use one when photographing from a helicopter or bus.
If you have the option, shoot through the open door of a helicopter, instead of a window. It will make it easier to get great photos. You can be buffeted badly by the turbulence with an open door, so be prepared for that.
- If you know you're going to be shooting through glass, especially if you're in a moving vehicle or helicopter, wear dark clothing to minimize your reflection.
When shooting with available light, as I did for the photo above, there are times when a little reflection can be a good thing. By focusing on the window itself, I was able to capture the neon signs in this bar window, plus the reflection of the sky, and the buildings across the street, to add to the shot's context and make the photo far more interesting.
Enjoy the "glass challenge."