warframe - How do I get any additional focus lens? - Arqade
Lens 2.1 - Fan Concepts - Warframe Forums
Serious Focus in Warframe: How to Remove Lenses - SideGamer
Squeezing More Affinity, XP and Focus Out Of Our Warframes – The Daily SPUF
Warframe: Focus Farming
Last time we had a Focus rework (2.0) all installed Lenses have been removed from frames and weapons. I would have appreciated it a great deal if it was done for this