Quote Originally Posted by neuroanatomist View Post
Thanks, Jonathan. Based on your efforts, the 140mm version should work well for the 600/4. B&H sells them (as special order items, with 2-4 week delivery; Google shows other US suppliers with stock on hand). I'll need to decide whether I'm going to take the 600/4, or use the RF 100-300/2.8 with a TC.

My older daughter is very excited about the eclipse, and at her request we are planning to drive up to New Hampshire for the event.
Glad this is useful. I take it you're planning to use the R3? I'm curious how the eclipse will appear in the electronic viewfinder, compared to the optical viewfinder of my 1DXIII. There are incredible nuances in the corona, and a huge dynamic range, that the EVF might not be able to display. You'll get the same photos (if not better) with the R3, but for the personal viewing experience, I'm wondering if it will match the optical view.