Dear Fredrick, I photo birds using EOS 5D Mark III and 400mm/f5.6. However, I find the details in my work are not so crispy and clear that deeply satisfy me. Your bewick's wren photo impressed me very much as it is also captured by 400mm/f5.6. I want to ask you for advice that how could I improve the quality? Which aspects can I make efforts? From focusing, exposure time, ISO or camere itself? If you do not mind, could I ask you for bewick's wren's raw full-size photo so that I can have a further review? And I will also be pleased to share you some of my works. My email address is hydroscwan@gmail.com or hydroscwan@163.com I look forward to your reply. Best Regards Sicheng Wan