Canon loaner lens
I had fun recently. I am a member of Canon's CPS program- Canon Professional Service. This entitles me to try almost anything Canon makes for 10 days. So, I thought I'd try the EF 200-400mm f/4L IS USM Extender 1.4x.
The lens is a beast. It is very sharp but that comes with some negatives- size and price.
Weighs almost 8 lbs and cost $10,000 For more info on lens: https://www.usa.canon.com/internet/portal/us/home/products/details/lenses/ef/super-telephoto/ef-200-400mm-f-4l-is-usm-extender-1-4x