I just wanted to share that I've released an iOS app that is kind of like the pana app, but full screen and with some basic image controls; anamorphic de-squeeze (1.33x, 1.5x, 2x) and brightness / contrast / saturation for working with V-Log.
Here's the App Store link: http://bit.ly/scopes-ios-app
Video showing lag is comparable or better than pana app
Scopes app + GH4 + SLR Magic Anamorphot 1.33x
Scopes app + G7 + Möller 2x
(G7 is not officially supported and needs you to start pana app first)
App Store link: http://bit.ly/scopes-ios-app