Sony a6600 vs Sony Alpha a7

“That 200-600 is a solid lens. I use it too. But you're right to struggle, and it's not you. You're fighting the A6600's AF. It's just not as fast as the newer bodies for BIF. That's the honest reality. Two things to try: 1. That lens *needs* sunlight. At f/6.3, the AF hunts like crazy on dark days. 2. Don't use "Wide" focus. It's just guessing. Try **Tracking: Expand Spot**. Lock onto the bird *before* it moves. It gives the camera a fighting chance. And don't believe the hype you see online. My keeper rate is tiny. I'll shoot 300+ photos to get maybe 30 "keepers." That's just the grind.”

“I saw this on a very used and beat up A7 that I was trying out (thankfully I never bought it). The lens would slide around quite a bit. I had never seen an A7 before so I thought that it was OK. But actually it's not normal. However this was a known issue due to heavy use on the original A7 which has a mount partially made of plastic. I though they had fixed it on newer bodies. I'm guessing a fall could also damage the mount and make it loose.”