AlanU wrote in post #18330472
Just yesterday I put my X-T2 to a challenging test. I documented my friends children's easter egg hunt. I noticed that with my 16mm or 10-24mm the autofocus lagged where I'd normall have no issues with my Canon gear. As guests arrived even quickly trying to capture parents hugging children the X-T2 lagged indoors using my 16mm with EF-X500 flash. X-T2 is definitely faster than my X-E2 and X-T10 but single shot still hesitated to the point it missed a good portion of what I normally capture with ease. Missing photos like that would anger any primary photog...
...I'm sure tempted to see how well a 16-55 performs in low challenging light even with flash. The lack of infra red AF assist has really caused me to miss shots I never ever would have missed with a dlsr with flash.
I remember when last years firmware update for the X-PRO2 came out that gave it the same AF as the X-T2, I gave my two kids a couple of water pistols and told them to run about the back garden and have fun. The X-PRO2 nailed shot after shot after shot and that was with the 56/1.2 - about the slowest of Fuji's XF primes. I've never had a problem focusing indoors in average lighting either since that update. If is gets dark you might have a different experience, as with any camera, including any of my 3 5D3's but Fuji's manual focus aids are so good it's just plain easy to use. I'd never even dream of trying to MF on a DSLR. If you are going to get the most out of your Fuji you need to look at how you use it differently. I know trying to get the Sigma art lenses to lock on with or without AF assist was a battle once the subject was moving so you have to know what gear will work given any situation.
The 16-55 is very good in low light Alan, if you have the light for 2.8, at an ISO you are happy with, it's fast. Even if you are using flash, remember the EVF can 'see in the dark', it's all round a great lens and I still use mine from time to time when shooting, it was my first Fuji lens, but I was always a prime guy so I prefer a few cameras and lenses. The 2.8 zooms will give you very fast AF at 1/125 when your ISO is 8000 or so - really I wouldn't worry about it. I don't think it is as fast, in bad light, as a EF 24-70 f/2.8 mark-ii L on a 5D3 with AF assist on but it's plenty close enough for shooting events with, even in low light. Over the last year and a bit of shooting weddings, amongst other things with Fuji I simply don't see the need to use anything else for now. The system has all that is required, for me anyway. I know others might differ but I can get all I need from Fuji. When it comes down to it you have to know your gear and what is going to work for the shot, and for you, otherwise you might just miss it.