Just to add to what Josh said. Definitely start with the zoom method, if you find that it's working really well just stick with it. For me I just couldn't get the brightness I wanted while watching HDR so I was always a little disappointed with that. I had to tone map all the way and or choose a lower gamma, neither which was as good as just having more light.
The lens definitively helped me and now i'm happy but you might find zooming does it for you so start with that.
Pioneer SC-95, Axiom M80, VP180 Dual EP500 all V4. ISCO III, RS540 + Stewart Cima Neve 133