I have been doing research for the past 6 months for a new set of spotting scope. I have narrowed it down to Vortex Razor and ZEN ED2 spotting scope. The Vortex is about $1600 and ZEN is $1000 with their discounts. I see the biggest difference is that Vortex has 85mm objective and ZEN has 82mm objective. Will that make significant difference in low light condition?