Toss apple slices with lemon juice as you slice them. Then toss together with sugar and cinnamon. Let sit while you roll out the pastry for the crust.
Roll out bottom pie crust and line a 9-inch (23cm) pie plate with it. Scoop in the apple mixture, and top with second crust. Pinch it around the edges, and poke a few slits in the top crust to allow steam to escape.
Bake at 425 F for 10 minutes. Reduce heat to 350 F. Continue to bake for 30 minutes, or until apples are tender when poked with a knife through a slit.