Originally posted by Prince Harbinger Thanks for the recommendations. The 100-400 isn't as sharp as the 200-600. Also using the 100-400 with a 2x teleconverter isn't viable when your losing a lot of stops of light and degrading the image with the 2x teleconverter. Let alone having to push the iso higher to compensate for that loss of light. As well as loss of AF features. Paying an additional grand for 2 extra mega pixels isn't worth it for me. Also having to pay for expensive storage for the larger files isn't worth it either. No one is going to notice the 60MP online. I don't have any intention of printing anything larger than a football field either.
I hate to be 'that guy' but why are you so set on full-frame then? You'd be able to get some exceptionally capable cameras in the A6600, save a bit of money versus a A7Riii or A7Riv (or A9, because frankly 24mp is fine for most, myself included as an A7iii user) and you'd have the additional reach of the APS-C sensor. There are some good wider options available for APS-C nowadays.
If you mean the not-yet-released A7iv, then it's a guessing game as to when that'll be made available.
What UncleVanya also means is that you would not need a separate Sony APS-C camera if you had the A7Riv, given the ability to use crop mode at 26mp
in camera. This also largely removes your requirement for a 2x t/c.
If you're not reliant on high megapixel count, as you mentioned, then even the A7Riii would suffice with a crop mode resolution of 18mp.
I don't know how much real-world sharpness MTF tests translate to, but most (if not all) photos I've seen with either the 100-400 or 200-600 have been immensely sharp.
If I had $7,000 right now and I wanted to fill your brief I'd probably go A7Riii, Tamron 17-28mm f/2.8, Tamron 28-75mm f/2.8 (or sigma 24-70/2.8 DG DN if funds allowed), either Sigma 100-400 (or Sony 200-600mm if funds allowed). Gives a minimum range of 17mm which is plenty wide for most applications and max of 900mm approx (using crop mode at 18mp).
Expensive end takes you to $5,500, inexpensive end takes you to around $4k. Gives you lots of room to play.