If your shed is weather proof, no problem using a panel. I have a 125 amp sub panel in my basement but it only has a 100 amp breaker supplying it. It doesn't have a main breaker in the panel, that is in the main panel under the electric meter. As long as the wire feeding your panel is in sync with the breaker supplying the panel you're OK down rating the supply to your shed panel. With 50 amps 240 nominal volts you could run a variety of equipment in your shed if you had the need. You could run all of that on a single 20 amp breaker provided you use 12/2 wire for the lighting. Given the outdoor location a GFCI would be required, and quite possibly an arc fault/GFCI breaker. That's what I had to use in my basement. So I have about $350 worth of breakers in the basement plus the 100 amp breaker in my main.