Retired fat guy with a camera wrote:
2x converters suck. I had one, I used it on a 300 prime L, mounted on a 1ds mark iii. I hated it, and I sold it. I have a 1. 4 that I am not wild about either. You want a sharper image? Sell it, and use what God gave you, your feet. Walk closer to your subject. It is just that simple.
So true .... longest lens I own is a 70-200 and I get some incredible bird pictures. 99% of what we share is on social media so you can crop the snot out of a picture, yup ... my 600mm is from PP :)