Posted June 19th, 2017, 11:23 AM
For me, the big lenses like the 150-600mm's are worth it, because probably my primary favorite type of photography when I'm not traveling is birds and wildlife...so I always get plenty of use out of such lenses. The decision for you I would think would come down to whether you'd only use such a lens on a trip once or twice a year, or if you'd be into wildlife or birds around home or most other days too. If only for the trip, I don't think it would be worth it - folks who don't regularly shoot wildlife would probably get really tired very quickly of the size and bulk of these lenses. Those who shoot wildlife and birds often accept the size and weight and become accustomed to it.
I have the Tamron 150-600mm which I use a lot for birding - I also shoot with many other longer lenses and have over the past 15 years - 200-500mm lenses, 300mm F4 lenses with TCs, 400mm F4.5 lens, and so on. I pretty much go birding every weekend when I'm at home, and also incorporate it into most of my vacations too at some point. I strictly use these lenses handheld - I like to maintain the flexibility and quick reaction time since much of my shooting involves quickly moving and fleeting subjects and flying birds. I use a pistol grip attached to the lens collar to help with stability when handholding. I am not shooting with Nikon equipment, but the lens is the same, so still can give an idea of the performance of a big lens like this at the longer end - most of these are light crops, just resized a bit - but will give an idea of the potential detail and clarity the very good Tamron lens can deliver - all of the following were taken with an APS-C crop-sensor body:
A small pig frog, about 15 feet away, at max 600mm:
Eastern screech owl on guard in her nest hole, in poor light and at 600mm, about 30 feet away:
Red-shouldered hawk in flight, about 50 feet out, cropped at 420mm:
Belted kingfisher, about 120 feet away, heavily cropped and taken at 600mm:
Yellow-rumped warbler, taken in the shade at ISO2000 at 500mm: