One of the problems of owning two camera systems such as Canon and Nikon is that neither system is always satisfying with regard to the performance of the lens and camera-body combination.
Nikon undoubtedly have the best wide-angle zoom (the 14-24/F2.
and the best sensors, as in the D800E. Canon used to have the edge with regard to a few very useful lenses such as the 24-105/F4 IS, the 70-200/F4 IS and the 100-400/F4.5-5.6 IS, but Nikon have now given us their own versions of similar lenses boasting VR, the 24-120/F4 VR and the 70-200/F4 VR. The old Nikkor 80-400 VR needs upgrading.
Since the longest Nikon lens I own is the the 120mm of the 24-120 zoom, I've been searching for a lens with Nikon mount that can replace my Canon 100-400 IS which I use with the Canon 15mp 50D body.
I wondered for a time whether the new Nikkor 70-200/F4 VR would be up to the job, using a 1.4x or 1.7x or 2x extender. However, my experience tells me that a 2x extender merely converts an excellent lens into a mediocre lens of double the focal length, or a good lens into a poor lens at double the focal length. If one also loses autofocus in the process, then forget it!
Being already convinced that a higher-resolution sensor will improve the sharpness and detail from any lens, except perhaps a really poor lens, I began considering other options. Are there any really good 70-300mm lenses available with a Nikon mount? Supposing I used a cheaper lens with a higher-resolving sensor such as the 24mp sensor in the Nikon D3200?
I began to wonder if this new Nikkor 70-200/F4, when coupled with the Nikkor AF-S TC-14E II 1.4x extender, for example, would produce sharper images than the Tamron 70-300/F4-5.6 VC USD when that lens is fully extended.
The Nikkor lens at 200mm with 1.4x extender becomes a mediocre 280mm lens. Surely that wouldn't necessarily be sharper than the Tamron at 300mm!
I then compared the cost and weight. The Nikkor plus 1.4x extender will weigh over a kilogram, whereas the Tamron is only 765gms. Not a significant difference, but a difference that would be noticeable.
However, the Nikkor lens with teleconverter costs approximately $1700, best price. The Tamron lens costs about $400, best price. That's a very significant difference.
So I bought myself a Tamron 70-300 VC with Nikon D3200 which I received a couple of days ago. Both lens and camera cost a total of $829, considerably less than the Nikkor lens alone.
So far, I'm very pleased with the results. The VC (vibration compensation) seems very effective, and the lens at 300mm and F8 seems sharper than my Canon 100-400 at 400mm and F8. The reason why I think it is sharper is because I'm getting very similar sharpness and detail using the Tamron at 300mm as I get with the Canon at 400mm, shooting the same scene from the same position.
I can't believe the difference between the 24mp of the D3200 and the 15mp of the 50D could entirely compensate for the difference in reach between 450mm and 640mm (in 35mm terms), unless one lens is sharper than the other.
I haven't bothered to resize the attached 100% crops because the greater pixel density of the D3200 sensor results in detail from 300mm lens being almost the same size as the same detail from the 400mm lens when both are viewed at 100% on screen.
My Canon 100-400 zoom with 50D attached weighs about 2.4kg. The Tamron zoom with D3200, about 1.3kg, a weight-saving of 1.1kg, not to mention the price difference.
I've also included a shot which simultaneously demonstrate the nice bokeh, the ability of the lens to focus on a small object in the scene, and the effectiveness of the VC of this Tamron lens, sort of like killing three birds with one stone. However, I admit that using just 1/50th sec at 300mm, hand-held, does not always produce acceptable results.