Photography & Cinematography 101 -
All About Green Screens
One thing that digital post production is very helpful with is the ability to dramatically alter the main elements of a photo to create new digital compositions.
Green screen cinematography is tricky. You need to light the green screen evenly - so the chroma-keyer (the software that allows you to select that single shade of green and then remove it from the image) only grabs the green from the screen. If the screen is not lit evenly, the keyer will need to grab a range of green from the image's spectrum - and this can reek havoc with your shot.
You also need separation from the main subject and the green background. If too much light is spilled over or reflected from the screen back onto the main subject - sections of the main subject will be removed as well. This can give you everything from odd, jagged edges, to entire sections of the subject just disappearing in the shot.
Green screen technology can be very helpful when shooting films on a budget. Car chases are expensive. You have all the safety considerations to deal with, stunt people, multiple sets of the same color/type of car (for crashes, for wide shots, for close-ups, etc...), multiple camera crews following the action, insurance, permits, etc... Car chases are VERY VERY expensive to shoot.
If you can do the majority of the chase on a sound-stage with green screens, you can shave the budget cost of a car chase by a factor of 10. I have shot several car chase scenes now using a mixture of real road footage and green screen footage to a high amount of success.
I shot all of the in-car footage for the music video "Burning Fuel" by Norwegian band Karnival Korpus against green screens. Half the video was shot in Norway and the other half in Los Angeles... I was able to make the footage match because of the lighting setups and the use of the same plates ( A PLATE is the background footage or image used to replace the chroma key - green - in a green screen shoot).
Having the controlled environments of the sound stages used - despite their location difference of over 5,000 miles - ensured that the footage shot would work together. This is another great advantage of shooting on a sound stage with a green screen setup.
USING GREEN SCREENS IN STILL PHOTOGRAPHY - The advantage here is the ability to control light variables and allow the model to focus on their work without the distraction of shooting on location. In the photo above I shot Los Angeles model Jennifer DeLarosa against a green screen in order to place her in a busy street in China Town - over 500 miles away. The second photo is the resulting image.
Below I shot an editorial "Wedding Dress" shoot with a model against a green screen to accomplish the same goal - place the model in a location that would be difficult to visit on a limited budget. In the case of the photo below the final plate was a shot from the South Pacific island of Fiji.
Green screen shoots don't have to be limited to people. For instance you can place products in different locations such as the Cannondale Bicycle below.
Green screens can be used with Photoshop and other post-production software systems to produce images that are completely different from the original... transforming an ordinary photograph into a digital illustration/painting. The images below are just a few examples of the dozens I have created in the past couple of years for various clients.
Honestly your imagination is the limit when you start experimenting with creating new worlds for your photography clients to explore.