Auto flash setting on X-T1

[fotoism]

First time X-T1 user here learning to use flash on the X-T1 and I am having some trouble.

 

I am using a flash (non-Fuji) in auto mode set to ISO 200 and F/5.6. I set the X-T1 and the lens to these settings and then turn the shutter speed to 1/180. Because I am in a dim room the viewfinder and LCD are both very dark. When I half-press the shutter the viewfinder will light up for a split second and become dark again, and when I fully press the shutter release the flash goes off and the resulting picture turns out okay. However, the dark viewfinder does not make focusing and framing easy. It will be bright again if I turn the lens back to A instead of f/5.6, but then the picture ends up totally over-exposed.

 

Am I missing some settings in the menu?