This is the final image that I drew with the lamp as the light source for the shade and shadow. Before working on this image, several preliminary sketches were completed. In the image below I became familiar with the shapes and proportions of each object using an elevation sketch. A center line was used as a guide for drawing the same shape on either side of the center. Other dotted lines were used as guides also.
The second image was a quick sketch working with the placement of the shade and shadow. Guide lines from the light source which hit the edge of the object to create the shapes on the table top. I adding value for the shade and shadow and looked closely at how the composition of the image was working. These two drawings provided the visual information I needed to move forward for the final drawing.