Chicken Bus - Lake Atitlan, Guatemala

I drew this a month after the trip, from a photo. Is that cheating? The sketch was intended as a study for a painting I still haven't done. Also to try out a big box of colored pencils I'd just bought. I sketched a lot on the trip, but they are mostly tiny vignettes (like a cartoon turkey in a burlap sack at the Chichicastenango market) and landscapes.