We are starting to plan a 40th wedding anniversary trip to South Africa and whilst this is *not* a photography expedition, my wife fully encourages me on these trips to do some semi-serious photography ;-) Anyways, I have been a (mostly) landscape photographer for a number of years now - but as I approach retirement I want to start picking up wildlife photography (birding in particular). And for this trip, mostly mammals of course, I'd like to bring appropriate gear. We will be staying at (mostly) private game reserves - and from what I've seen that can result in a lot of close-in photography as you can get quite close to the animals on game drives. But, of course, you also need some distance. (sigh). I currently own the 24-120 + 100-400 (+ 1.4TC) for my Nikon Z9. [Before retirement I am looking into a long prime lens for birding - maybe the 600 or 800 PF?]
In my research I've seen a lot about (a) needing faster lenses for early morning/evening times, (b) that you really need to get to 600mm if at all possible, and (c) having two set ups with you can really make a big difference. To that end I am thinking of renting a Z8/Z9 as a second body and taking these two lenses. I know w/ the 1.4TC I get to 560mm w/ the 100-400mm - and I can DX it into a 20MP 840mm f/8 lens at the touch of a button. My thoughts are to have the 24-120mm on the rented body and the 100-400mm on the Z9 in lower light situations and add the 1.4TC when the light is better. [That would give me a focal distance range of 24-400/600mm(DX) in low light and 24-560/840mm(DX) in good light]
The question is then: would I really suffer during the low-light periods w/ the relatively slow lenses - f/4 at best, f/5.6 at worst? Should I really be thinking of dropping the (say) 24-120mm and renting some fast-ish prime instead?