Should I upgrade from a6400 to a7iv?

[WhistlerNorth]

The best budget FF combination I could recommend would be a used A9 combined with the Sigma 100-400 DN, which can be had for under $1,000 USD on Fred Miranda. I have that lens, along with the GM 100-400mm and have found that it is actually sharper between 200-400mm than the GM lens (Dustin Abbott found the same thing in his tests). The only downside is that FPS would be limited to 15fps on the A9.

Very interested in your comparison of the new Sigma 100-400 vs Sony GM 100-400. I have an A6500 and 70-300 and looking for more reach for a wildlife trip next spring.

I just put down a deposit on the new A7IV so figuring out what would work in the lighter end as I am female and small in stature. I would not be using it at fast FPS.

What camera are you using the sigma on?

I had the Sony 70-300mm. The Sigma 100-400 is sharper and has much better contrast. I am using it on the A1 and A7rIV.

So which lens do you use most or does situation dictate— like weight depending on shooting location.

I get 30fps with the GM lens and 15fps with the Sigma on the A1, so I use the GM for BIF. The GM lens also makes a better macro lens.

Thanks Jeff— Your input very helpful. I have a dedicated well rated macro lens and my trip next spring is focused photographing whales and bears up the BC coast. I am ok with less frames per second and birds in flight not my main focus. Going to check out the Sony 100-400 GM in couple weeks at local camera store as my helpful advisor bringing his in. He is going to show me how he sets it up to shoot on monopod. I just want to see how big and heavy it is to rule it in or out. Presently not using large zoom a lot — usually just on special wildlife trips and moon shots. Would take a lot to justify $3,400 CDN for the Sony 100-400 GM. Probably doing moon shoot later this week as moon and weather looks good my 70-300 on Sony a6500.