I’m still playing with my new(ish) Tamron 150-600mm telephoto lens and thought it would be fun to see how large an image of the moon I could capture with it. I shot this on the D90 at full zoom so the effective focal length was 900mm (the D90 has a crop sensor which gives me a 50% focal length bonus). What you see here is about 1/4 of the area of the frame. It seems that, to get a frame filled with the full moon, you really need a VERY long lens indeed!
For the technically inclined...