simple one time flash

So, my first electronics project. I want to build a simple device that flashes one time if you press a button. just for, lets say 1/50th of a second. after the flash, the button is released and we can start from the beginning. like a test button on a fotoflash. i have absolut no knowlegde how this can be done. i hope my sketch points into the right way. i think this is a pretty simple task but not for me. would be nice if you could have a look and give me some advice.