A 50mm lens is a very short focal length for photographing the moon and will give a very tiny image. Also, during a total lunar eclipse the moon itself becomes very dark (usually a dull copper color), as all the sunlight falling on it is obscured by the earth's shadow. (It's much less spectacular than a solar eclipse). This means a short time exposure is needed, and the movement of the moon in the sky during even a few seconds will blur the image.
I've photographed a lunar eclipse, but using a telescope on a guided mount (and, dare a say it, a d****** camera, so that I could see the results immediately and correct for exposure, framing, etc.
Not trying to discourage you from having a go, but, given the limitations of an ordinary camera, slow film and a standard lens, I'd probably just enjoy it as a spectacle to watch, particularly if you have a pair of binoculars available.
There's loads of technical info on the eclipse itself on