Tamron 18-270mm VC on D90 a sure win combo
I just got a Tamron 18-270mm VC for my D90 and I have to say it is a very good lens. Forget the Nikon 18-200mm VR (I had to go through four of them to get one good sample - these were Mk 1), the Tamron is the best choice if you want an all-in-one general purpose and travel lens.
For those who complain about softness, I think they either expect too much or just want the lens to fail no matter what. I found the lens to be mostly sharp wide open. The only exception was at 200-270mm which had a very slight softness at 200mm and noticeable but not serious softness at 270mm which sharpened up immediately with stopping down to f8. The lens is sharpest in the mid-range and very slightly soft in the wide and tele ends but that is easily corrected by stopping down at those ends, or even in a photo editing program as the softness is not drastic.
Autofocus was fast and sure in normal room lighting, even at the tele end. I've also tried AF at tele end in low-light and was surprised the AF was fast with very infrequent (emphasize "infrequent") hesitation of half a second, again only at the tele end in difficult low light, otherwise fast and sure. Most if not all lenses in this category, however, are prone to such weakness anyway.
For those using DX cameras and who envy the D700 users and their excellent Tamron 28-300mm VC, envy no more. I admit I am a fan of megazoom lenses and their convenience and light weight yet high utility, but having tested quite a few, I would only recommend with careful consideration and I can highly recommend the 18-270mm VC for DX users!
Other megazoom lenses worth considering:
FX - Tamron 28-300mm non-VC, Tamron 24-135mm and Tokina 24-200mm (last two are rare)
DX - Sigma 18-200mm OS HSM (but not as good as the Tamron 18-270mm VC but has very fast AF even in low light)
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