The 13mm images are with the Viltrox, correct? Those look way better than the Sigma 16mm or the Fuji 14mm if so...
Yes, exactly - it's Viltrox 13/1.4
It was third time I was shooting concert using same setup: X-H2, Viltrox 13/1.4, Viltrox 27/1.2 and XF 56/1.2 R
And I have some my impressions and thoughts from field usage, I would like to share with You guys.
First of all, let me remind You that concert photography is one of the most demanding and challenging photography genre when it comes to autofocus - right behind birds in fly and sport photography.
So I'm very happy to report, that autofocus in X-H2 is very very good for this job.
With lenses like Viltrox 13/1.4 and Viltrox 27/1.2 I have almost zero missed shots, due to AF errors.
With dinosaur lens like XF 56/1.2 R I have like 7/10 shots in focus, either using AF-S, or AF-C.
Not bad Fuji, not bad at all

Dunno if Sony or Canon users has better AF results in such scenarios like very darkly lit concerts.
Even if they do, I think that in this regards X-H2 autofocus is nothing to complain, rally.
Second thing is X-Trans IV and V sensors.
With denoising software like DXO PureRAW 3, You can easly shoot up to ISO 3200 and final results are just jaw dropping (if You consider it's aps-c sensor).
Such IQ in final result was unthinkable couple years ago

Seriously, just keep ISO up to 3200 and I hardly believe, that there is one who will complain for amount of details or noise levels (when publishing on 4k screens or even A3 prints)
Viltrox 13/1.4 <- this lens is my biggest surprise for concert photography.
I bought it mainly as a UWA option for my lame landscape shooting during holidays, and It turns out, that I use it for about 50% of whole images I shoot on event.
Combination of f/1.4 and such wide FOV is rally something what got me hooked, as I was used to shoot with 24mm primes (in FF terms) for wide angle shots.
I rally do think, that Viltrox 13/1,4 is best UWA lens in Fujifilm X system for concert photography.
Not sure how about XF 16/1.4, but I get feeling that Viltrox 13/1.4 FOV is more useful, and You can always crop a little in post.
Viltrox 27/1.2 <- I prise this lens in high heavens, best standard lens I've ever had but.. I find its FL somewhat boring in concerts, it didn't fit my shooting style for such job, so in practice I almost never use it.
XF 56/1.2 R <- not great, not terrible. Not best choice for concerts to be honest.
Needs to be stopped down to f/1.8 to match acutance of both 13/1.4 and 27/1.2 Viltrox lenses.
Focal length.. well, not exactly what I'm looking for documentary photography (subjective)
XF 56/1.2 R autofocus is also well known for being sluggish and unreliable, although I've got quite decent AF results when using XF 56/1.2 R with X-H2.
I love old XF 56/1.2 R rendering in portraits.. "look" I can have from this lens, was main reason to buy it, as Im shooting mostly portraits.
But if I would aim more in concerts and less in portraits, I would choose Viltrox 75/1.2 over both old and new XF 56/1.2 and never looked back
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https://www.flickr.com/photos/maciej_k/