old glass

this photo was taken off the top of the north hill in malvern with a tokina 60-300 and a teleplus 2x converter the bunglows are 1.3 miles away settings on the camera where 600mm on the sr f11 @1,250 im guessing with the converter on it should be different? dont think it bad for a distant shot taken in raw and devolped in jpeg please let me know what you think