And they're right, of course, which is why they're pros. Nothing I can say will really explain it, you just have to try one to really understand.
Now, in spite of that, I don't own one yet. I've been renting them when necessary because, from a purely business standpoint, buying one outright hasn't made financial sense yet. I've also been renting different versions so that I can get a feel for which one I'd like to eventually buy. To date I've tried out the following:
Nikon 70-200 f/2.8 VRII
Nikon 70-200 f/2.8 FL
Tamron 70-200 f/2.8 G2
Nikon 70-200 f/4 (I know it's not an f/2.8, but I'm a sucker for lightweight lenses)
I'm not going to spend a lot of time doing detailed comparisons of optical performance other than to say that they are all very good because other, far more qualified folks have done that to death (plus, I never had all of them at the same time to do a real side-by-side). But I do want to share a few things that I learned about them.
|The Nikon VRII and the noticeably lighter Nikon f/4.
The zoom rings on all of the Nikon lenses have a very consistent feel to them: light enough to zoom easily, but not so light as to shift focal length should you take your hand off of the ring. The zoom ring on the Tamron lens, on the other hand, is stiffer and takes a bit more effort to turn. None of them feel bad to me and I suspect that liking one or the other will boil down to personal preference. For me, shooting the Tamron on land feels better because it feels more precise, but the Nikons feel better on the water because I'm already expending that much more energy just to steady myself that every little bit of reduced effort helps. I suspect that the zoom ring on the Tamron will loosen up over time as zoom rings are prone to do, but ideally I'd like it to be a bit looser now.
The Ring of Power
Speaking of zoom rings, not all of them are located in the same place. On Nikon's VRII and f/4, the zoom ring is located closer to the camera, and on Nikon's FL and Tamron's G2, the zoom ring is closer to the front element. Two of these arrangements feel quite natural and balanced nicely, the other two not so much.
The f/4 is just about perfectly balanced for a smaller body like the D7200 I used it with. It doesn't have a lot of weight out front, so keeping your grip closer to the body keeps the whole camera well balanced. Likewise, the Tamron G2 is also very well balanced for a smaller body; with more weight from the heavier lens out front, moving your hand further forward on the lens keeps the weight distribution right. Also, and very importantly, the focus ring on the Tamron is placed such that your hand doesn't tend to rest on it (at least not my hands), so having my hand that far forward doesn't interfere with the focus.
|Nikon FL, as deployed.
Feet of Strength
With the VRII, my preferred method of deployment is simply to remove the tripod foot from its collar and attach my cross-body sling to the tripod mount that remains in the collar. This makes for a very slim setup and balances well while by my side, and it doesn't get in my way while shooting. Nikon really got the tripod collar right on the VRII and FL; I wish someone would come up with a similar version for the Tamron or other lenses.
|Nikon FL, foot rotated. See how it rested on my palm***?
|Nikon FL @ 75mm, f/2.8, ISO 400, 1/200sec.
Although the Tamron lacks the cool removable tripod foot of the Nikons, it does have an Arca Swiss mount built into it's tripod foot, so it's easier to actually attach to a tripod. (The whole collar is also removable, but the lens seems rather awkward without it on.) I feel like an ideal tripod mount for a 70-200 would combine the easily detachable foot and permanent collar with a secondary mount of the Nikons with the built-in Arca Swiss mount of the Tamron.
The f/4 has an optional tripod collar, but I suspect that using it would be largely a waste. The lens is so light that the camera body's tripod attachment point should works just fine for a cross-body sling and should work equally well for tripods.
Hippy Hippy Shake
|Tamron G2, as deployed, just like the FL.
The Nikon systems tend to jump around more as I'm composing a shot. This has no impact on the final image as it still freezes the frame when the shutter is released, but it does sometimes make composition trickier. Also, if I were to shoot video (which I rarely do, at least through lenses like these), I imagine the video would likewise be jumpy. Nikon seemed to design their system with minimizing power use and instantaneous, instead of continuous, performance in mind, which makes perfect sense for a still camera.
On the other hand, the Tamron system held the image much more smoothly over time. When looking through the viewfinder I had an easier time composing shots, and I imagine that video shot through the Tamron lens would be smoother as well. In terms of overall usability, I definitely prefer the image stabilization of the Tamron lens.
|Tamron G2 @70mm, f/2.8, ISO 200, 1/400sec.
The Almighty Dollar
The difference in price between these lenses is wholly non-trivial. The Nikon f/4 and the Tamron G2 are both about $1,400 when bought new. The Nikon VRII was last available at $2,100 new but isn't in production anymore, and sells used for about $1,400.
The Nikon FL sells new for a whopping $2,800. I could buy two of the other lenses and have one as a backup for the price of a single NIkon FL!
Price-wise, the VRII felt about right to me when you could still get it new. Paying a premium for the factory warranty and Nikon reliability would have been worth the extra money. I'm not opposed to buying refurbished or used (in fact, most of my gear is refurbished), but for a major investment like this I'd rather buy new for the factory warranty. This means I probably won't be buying a VRII.
|Business end of the Nikon FL
As I mentioned above, the Nikon f/4 isn't rugged enough for my needs, so that's a no-go as well in spite of it's comparatively low pricetag and great optical performance.
That leaves me with the Tamron G2. It's rugged, it's ergonomics are right, it's image stabilization is top notch, it's price is reasonable, it's still available with a full warranty, and it produces great images. I think this puts the Tamron G2 into a sweet spot in terms of value and performance for me as a part-timer. I have some reservations about its long-term reliability since it is coming from a third party manufacturer, but the lower cost and 6 year warranty help balance those reservations out. Once I get my income stream a bit more solid, I'll almost certainly be buying one.
*The other two being the normal zoom and the wide zoom in f/2.8. Most current normal fast zooms are 24-70, and the wides vary by manufacturer, but Nikon's is 14-24.
**I do not, under any circumstances, recommend or condone the use of expensive photographic equipment as a blunt weapon. Or, for that matter, beating people with blunt weapons in general.
***I cannot quite emphasize how tricky it is to take a picture of yourself holding a camera with a heavy lens, one handed, with a second camera, also one-handed. Heh.