Toment wrote:
With CIZ, you get 400mm equiv. If you shoot in crop mode, it's 700mm. BUT you only have 28 wide, so I take the 17-28. MHO
Exactly my advice too, take the Tamron 17-28mm for wider shots. I love that lens. You will sometimes need longer than 200mm so be sure you know how to use Clear Image Zoom in both fullframe and APS-C mode. Your 61mp of the A7RIV will cover you with still great image quality when cropped in.
I have been doing this as a pro for almost 50 years shooting all subjects around the world, and whereas for Costa Rica I would also take my Sony 200-600mm along plus 1.4X and 2X TCs, if you want to save weight, then you pretty much can do it all with the 17-28mm and the 28-200mm using CIZ and APS-C mode. Remember CIZ only works in jpeg shooting, not in raw or raw+jpeg settings.
One question, I know you want to travel as light as possible, but do you have a backup body to take, or does someone going on the same trip have a spare Sony body to loan you in the case you have any issues with your camera. I know my A7RIV has been bulletproof all around the world, but I never travel without a backup camera, as anything can happen, like tripping or a fall, and with no backup camera it wont matter what lenses you bring.
FYI, I have owned Sony A6500, A7RII, A7RIII, A7III, A9, and currently own A7RIV, A1, A7SIII.
Maybe rent or borrow a Sony APS-C body to take as a backup, they are fairly compact and would save your trip in a pinch. They can work with all your fullframe lenses. This may be a once-in-a-lifetime bucket list trip, so dont risk it to a camera failure. Just my two cents here from my personal experience.
Have a great trip.
Cheers and best to you.