As covered in my previous post, I have been testing some lenses for an upcoming trip where we will need to travel relatively light while still wanting to cover a range of focal lengths for landscape, wildlife and bird photography. One lens I have been waiting for months to try is the Tamron 150-600 which has been getting great reviews. As a result there has been a severe supply/demand mismatch with a long wait especially for the Nikon mount version, which I have been waiting for over 3 months to get hold of. When speaking with the rep at the recent NZ Geographic awards evening he told me that Tamron had been surprised by the huge demand and were having difficulty manufacturing adequate numbers. It was quite a surprise to walk into Carters Photographics in Tauranga to find one on display which they were generous enough to let’s us take out for a test session on birds.
There are plenty of online reviews so I’m not going to go into details on specifications but rather just give a quick impression on practically using the lens, mainly for birds in flight. The first impression was of a substantial, solid feeling lens with smooth controls but a big rotation needed to get through the full zoom range. Even mounted on a large body (D300 and D810 both with battery grips) gave a bit of a front heavy feel when zoomed to 600mm. It is easily handhold-able with a nice large lens foot sitting easily in the hand allowing your fingers to rotate the zoom ring. Sharpness was good up to 500 where it dropped off a little but the real problem was the focus acquisition on flying birds despite being in bright sunlight. Tested back to back with the the Nikon 80-400 AFS, the Tamron battled to lock and hold focus on flying seagulls while the Nikon rapidly locked and held focus. A Nikon 70-300 VR also was quick to lock and hold focus on the same subjects. Part of this is the maximum aperture of f6.3 at 600mm which is less than the f5.6 that Nikon specifies  as required for the D300 but the D810 operates down to f8 and was similarly hampered by slow focus acquisition. We were testing in bright light on high contrast subjects which should have allowed the best performance and things would probably deteriorate as light levels drop.
The Tamron 150-600 is a really versatile lens with a huge zoom range and very good image quality at a very affordable price but for me the performance on birds in flight was a complete deal breaker and I would have been very disappointed if I had purchased one before being able to test it. For static subjects it would be a great lens and I can imagine it being a good lens to take on safari for large mammals and perched birds. If birds in flight are important subjects the much more expensive Nikon 80-400 is a better tool being light, well balanced and fast to focus despite lacking the same reach. It will be interesting to see how the two newly announced Sigma 150-600 lenses will compare with the Tamron and Nikon once they become available.