An interesting concept. The old 180-600 was a true beast and heavy as a boat anchor. Plus it had f/8 max. aperture.
When I saw the subject heading I first assumed someone had reviewed the old AI 180-600/8*ED. The new lens has the same filter size (95mm), is over 100mm shorter than the old lens+FTZ and about 1.5kg lighter.
The old lens focuses down to 2.5m for an impressive 1:3 magnification. The new lens gets to 2.4m at 600mm with a maximum magnification of 1:4, which suggests more focal length reduction at close range (perhaps to compensate for "focus breathing"). Sometimes newer isn't always better.
At the wide end the aperture is f/5.6, a full stop faster than the old lens, narrowing down 1/3 of a stop to f/6.3 at 600mm, still a useful 2/3 stop faster than the old lens. With only 1/3 difference between wide and telephoto ends, it is nearly a constant aperture zoom.
The new 70-180/2.8 is also interesting. It is impressive that they managed to fit a 180/2.8 zoom (64mm entrance pupil) inside a barrel with 67mm filter. The Nikon 180/2.8 primes had larger 72mm filters, and zooms usually need larger filter sizes than equivalent primes. I wonder if they cheated on the focal length or max aperture, or if the lens suffers from strong vignetting? It should be a popular lens, and might fill the space normally taken by a 70-200/4 lens, gaining some speed in exchange for a shorter zoom range. The lens also reminds me of the series-E 70-150/3.5, being an affordable and relatively compact telephoto zoom with somewhat restricted zoom range but with faster than usual aperture.
