Vidalgo

Funny: there are 2 Fuji S1 cameras.

Diopter correction of X-T1 works fine for me (but can be the real problem with another Fuji camera when correction range is shorter, like X100). There is an another moment: when I look to screen I must to use glasses, and if at next second I want to look in viewfinder - I must to remove glasses otherwise the viewfinder will show me invisible corners. And vise versa. So most of shooting time I use viewfinder only, without glasses. It's also applicable to the stock eyecup. In portrait orientation this long eyecup is a bit less comfortable for me than the stock one, but in landscape mode serves better.

I have second Fuji battery as a spare, and my needs never exceeds rate "2 batteries per day". On other side, stock charger is a bit bulky for travel. So I got an cheap China-made compact charger with 2 batteries. I add to bag one of these nonames as a "unexpected spare". Sometimes I use it for short period, for moments when both of my Fuji batteries are moved to chargers, and it works ok. For such my need maybe each third-party battery with correct voltage and dimensions will be fine, and cheaper is better.

I can't use glasses with this eyecup. Sadly, it was claimed feature - "shooting with the naked eye or with glasses". With glasses, i.e. eye moved a bit from eyecup, a kind of vignetting occurs and corners of EVF becomes shaded.