The a7iv is a great balance if price and performance. It's not a blistering fast high grand rate camera, but it's good at lots of things. The only two negatives I've seen are 10 fps max frame rate and a crop on 4k 60p

I bought a used one for my wife and it works quite well. I shot Minolta for 20 years and then made the natural move to Sony A mount and now E mount. Some dislike the Sony menus, but I never had a problem. What I found with the RX10 is the same as my a99, a99ii, a9ii and now a1 is this: take the time to set the camera up the way you want including all of the custom buttons and function menu (one of the best things about Sonys is that they are extremely customizable). Once you do this it will be a vary rare thing that you'll need to go into the menus for anything. Also, I've had many of Gary Friedman's books and recommend them.

As it has been indicated, there are many ways to get where you want. I will throw a recommendation for Godox/Flashpoint. The stuff just works and they've got flashes and strobes from under $100 to 1200 watt seconds and everything in between. It's also all system agnostic so you can switch most things at will.

I would trust the Lensrentals comparison, but the fact that one is better than the other does not indicate there will be a problem. Additionally, to be technical, one would need to define weather sealing against what. For instance, is it rain, humidity, water from underneath, etc. My hunch would be some are better sealed in some areas but not as well in others. The suggestion to reach out to the two Sony ambassadors as one can't get much more out there than Paul Nicklen. Reaching out to Steve Perry is a good idea and I'd recommend Mark Smith as another reference who I'd trust (search for his bird photography on Youtube).

I guess for me, I'm sure there are better sealed cameras than my Sony A1 (and a9ii, a99ii, a99, a700 and a100 before it), but I haven't had a problem nor have the majority whom I've followed or read. From my perspective it's more of a theoretical problem than a real one. Finally, I have no interest in an extended warranty as I prefer to insure all of my equipment for all damage, loss or theft, including water damage.

Mark Smith is also a good resource who's shot the A1 and R5 and has a video specifically about moving from the D850 and D500 to the a9 (and later to the a1). Arbitrage on Fred Miranda also shot them and has made many posts speaking to their strengths and weaknesses.

I suspect there are many reasons, but one is that Sony licenses their e-mount AF protocol whereas Canon and Nikon do not. With Sony's a-mount, Nikon's F and Canon's EF, none were licensed and the 3rd parties had to reverse engineer the protocol. They worked pretty well, but could have glitches on certain cameras and sometimes required update (and sometimes just flat wouldn't work). With mirrorless and the new mounts, AF protocols have likely changed and I suspect the 3rd parties want to be confident their lenses will perform well from camera to camera as they are released. In Sony's case, with the licensed protocol (which includes the ability to update the lens firmware via the Sony camera), there is some confidence of future compatibility and performance.

That's a good point. I shoot some birds in flight at f6.3 and f8 against white and blue skies and still don't see an issue, but that's a very good point.

I've never had much of a problem on my DSLRs or my mirrorless (all Sony), but try to be careful (camera off, pointed down, not too dusty an environment). I also choose not to have my shutter close when changing lenses as I feel the shutter is more susceptible to damage from potential external forces than the sensor is.

If any of your lenses are screwdriver drive the LA-EA4 will work with all of them. If they all have motors in the lens then if go with the LA-EA3 as it'll utilize the AF sensors on the camera rather than those in the adapter (as the LA-EA4 does). The LA-EA5 will also work well with the a7iii if the lenses have motors in them (it has a screwdriver drive in it as well but it only worked with three cameras and the a7iii isn't one of them).

I've shot very little soccer, but what I have I've used something in the 70-400 range. I setup at the end my niece's team will be trying to get to to score in. I don't really have the reach to cover the full field, but most of the action at three other end is my team's backs. From the sidelines I get mostly side profile shots, but from the end I can get their faces and shots. 200mm would be to long for the way I shoot.

Price: $3,400.00
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Item condition: 9+ Shows little or no signs of wear
Shipping instructions: USPS Priority Mail

I preordered this camera on its announcement day and used it as my primary camera since replacing it with an a1. It has 564 clicks on the mechanical shutter and just under 10,000 clicks total.

Included are everything that came with the camera originally (camera, unused strap, charger, battery, cable clamp, usb cable).

Price includes Paypal fees and USPS Priority insured shipping including signature requirement. Please see included pic for more information and let me know if you have specific questions or would like to see more pictures.

Are you sitting raw or jpeg?
Have you micro focus adjusted your lens?
If you're sitting raw, what software are you using to convert?
What type of birds do you shoot, small and fast or larger and more slow?

How close will you be able to get from your subjects? Given that it's indoors I'd be looking for something with a 2.8 aperture (70-200 maybe). If you can get closer then options open up. Also, it looks like lensrentals.com has a good selection of A-mount lenses still available.

From a sharpness standpoint, the Sigma is sharper and much loved, though huge. The Sony Zeiss isn't known to be terribly sharp with a bit of variation, but many love the lens (I have neither). With the recent Sony 35f1.4 GM, there are quite a few of the Zeiss lenses available used at pretty good prices.

Stacked sensors can typically read out faster so I expect the R3 to be better in this respect than the R5 and R6.

In comment to a different post: As far as I know, the readout speed is designed into the sensor and electronics and not something that can be changed via firmware.