Enemy Territory has the built-in ability to capture screenshots. By default, the F11 key will be bound to a variation of the '/screenshotJPEG' cmd. You can reconfigure this key with the in game menus (e.g. ESC -> Options -> Controls). Once you hit your screenshot key, a new .jpg file will be created inside of your etmain/screenshots/ directory. Check your console to find the exact filename.
At times, you won't be able to use any of your binds. For instance, when in the limbo menu, you will notice that your screenshot bind will not function. In order to get around this, you can do the following:
seta screencmd "toggleConsole; wait 100; screenshotJPEG"This command will set a persistent cvar called 'screencmd'. You should only need to do this one time and it should be written to your profile config so it will be set the next time you start et as well. After that, whenever you want to take a screenshot and your screenshot key does not work, bring down the console and type
vstr screencmdNote that it won't do any good to bind that to a key since binds will not work on such a screen.