The 100-400 is excellent…not as sharp at 2:1 in LR as the 600PF but at screen output resolution the differences go away due to downsampling. I find it quite acceptable. I added the 180-600 recently as well…it’s rated a bit better than the 100-400 (and I agree) which is strange since the latter is an S lens…but it is what it is. For me…the 600PF has the TC on most of the time for reach without weight and again it’s far better than adequate…so the 180-600 gives better overall coverage with less gap than the 100-400…albeit at the cost of weight and MFD which the shorter has and it’s outstanding for my close in work which isn’t enough to justify carrying a dedicated macro lens. Which of the zooms I take depends on car vs hike vs length of hike as well as experience at a location because some places 180 is too much lens.
Given my use of the 600PF as the exotic lenses are just more than I would care to carry…if I had to pick just one of the zooms it would be a hard choice…but I would probably slightly favor the 180-600 despite its extra weight. I did t one time have an 800PF on order…but the weight stopped me from getting it…and after trying Steve’s 600TC in Tanzania I confirmed that I made the right choice for me. My other go to youtube guy Hudson Henry recently got the 400/2.8 which with the built in TC and externals gives a nice batch of lengths…but again, too heavy for me to be interested in one…although a 400/560/800/1120 combo for a single lens/body combo is intriguing, but I’m also not gonna pay the price for one even though I could…but it’s more a weight decision than cost.
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