The gap idea stemmed from the 100mm being a fair amount more on my crop sensor, I am extremely pleased with all of the shots I get from that lens but thought I would need something shorter for portrait work. The 70-200 talk is a different lens issue entirely. I have a Sigma 150-500 that I am not totally pleased with and before returning it I wanted input on a superior replacement for it while being mindful of my budget. This lens will be for wildlife, distance wildlife photography. Sorry if i muddied any waters in previous posts.