Thank you for the detailed answer. I also thought about duplication/redundancy so plan to have backup bodies/lenses. Couple of questions if I may...
600mm PF - how useful would it be considering that 400mm cropped to APS-C would be ~20Mp and 560mm? Did you encounter many situations where a longer than 400mm lens was needed? I could take my Oly 100-400mm with OM-1 which would have an eFOV 200-800mm, but I thought most animals/birds are close enough so that 600-800mm would not be needed.
What was the lens that you used on Nikon One AW that was equally waterproof? I have an Olympus TG-6 with waterproof housing and 2 strobes but this setup is bulky and heavy.
I have a Cotton Carrier 2-body harness (one cam on the chest, another on the belt). I was also concerned about kneeling and banging equipment on the rocks. I will have a backpack with me to store/protect the equipment if needed.
Thanks again for the tips!
I was using a cropped sensor Nikon (the D500) so when I used the 400 mm end of my 80-400 mm zoom, I was at the same field of view you would get with 600 mm on full frame. Or similar to what you would get with a 400 mm lens on a full frame camera with cropping in camera or in post to APS-C size.
I have seen the advice that all you need is 70–200 mm. That was not my experience. I was glad to be able to get to 400 mm on my cropped sensor D500.
I think the ability to crop a full frame camera (especially one with high resolution like the A1) with 400 mm to an APS-C size would get you most of what you might want. There were a few times when I would have liked something longer than 400 mm on my cropped sensor camera. Mostly for birds in flight. Or at times for the smaller birds that were not as close (I was trying to photograph as may of the Darwin finch species as I could find). I’m quite fond of photographing birds. I did some cropping even with 400 mm on my cropped sensor D500.
As I think of it, I did have another camera with me. A Nikon One V3 and a 70-300 mm Nikon One lens. One inch sensor. That had a field of view equal to 810 mm on a full frame camera. Very small and light. I didn’t use it much. But one day we were watching a number of blue-footed boobies plunge diving for fish. I think it may have been at the beach on Gardiner Bay. The birds are very fast as they hit the water. The V3 would shoot 20, 30 or 60 frames per second, uncommon then. My best plunge diving shot came with it — given the frame rate, the photos included the bird’s bill touching the water, the bird half way in the water and just the feet sticking out above the water. Focal length was great here and it was a sunny day. But the fast frame rate was the really nice part. Hard to keep the birds in the frame, but great fun.
There is a wide range of wildlife in Galapagos. We photographed smaller birds — e.g., finches, warblers, flycatchers, mocking birds, shearwaters; medium-sized birds — e.g., various gulls (including the very rare Lava gull), various shore birds, tropic birds, blued-footed, red-footed and Nazca boobies, Galapagos penguins, green and night herons, Galapagos hawks and Galapagos short-eared owls; and larger birds — e.g., flightless cormorants, brown pelicans, great and magnificent frigate birds, great blue herons, flamingos, and Galapagos (or waved) albatrosses. I’m sure I am forgetting some. Some flying or diving, some on the ground or rocks, and some perched on branches. The adult Galapagos tortoises are generally huge and sometimes fairly close. The marine and land iguanas are not small and often fairly close. Mammals we saw were mostly sea lions and a few seals.
Having something that gets you to a shorter focal length is important for wildlife too. Most of the people on my trip shot Nikon and used either the 80-400 mm zoom or the 200-500 mm zoom. I did see people who had the 200-500 mm zoom needing to step back when creatures were closer. It was good to have the 80 mm end of my zoom (120 mm field of view on a full frame camera) for animals and birds that were close.
Do you have a 1.4x TC for your Sony 100-400? If so, that might be useful to have and light to bring along. My Nikon Z 100-400 mm takes the Z 1.4x TC quite well (leaves you at 560 mm and f8 on the long end) and can be very useful if there is enough light. I would probably bring the Z 600 mm PF if I went now. It’s light — only a bit over 3 pounds — and takes a Z 1.4x TC well. It might have been particularly useful on Genovesa Island, South Plaza Island, and Espinola Island (the only island with albatrosses) where we saw lots of birds in flight.
The concern with the Oly 100-400 is that it might be a little long for animals and birds that are closer. Of course, you may have other lenses for the Oly.
I used an 11-27.5 mm lens on the Nikon One AW. There was also a 10 mm lens for it. If I recall, there is a 2.7 times crop factor for the Nikon One, so this had the field of view similar to full frame at 29.7 mm to 74 mm lens. Equally waterproof, yes. Not perfect and I recall reading that some people had problems now and then with the camera or lens. I did not. I greased the o-ring before every trip. I think they were rated to 49 feet. Again, not made any more.