I thought I would post this just for the fun of it.....
Shot with a Canon 30D & a 100 - 400 IS @ the full 400mm on a very gray day.
Please keep in mind this pic has be heavily cropped and in the full frame both are not much larger than specks. I was standing at the Langley Municipal Airport and the west bound Cessna is probably 2 or so miles away if not more. The 747 was hanging out over the Vancouver / Richmond, B.C. area waiting it's turn I suppose. The Cessna might have been at 3000' where as the 747 much much higher. ( all measurements are just a guess ) It was far enough away for me not to be able to ID the aircraft type until I got home and zoomed in on it.
In any event..............