Well, would you look at that? As of this morning Nikon has added a most budget-friendly 70-200mm f4 constant to its line-up. Formally known as the "AF-S NIKKOR 70-200mm f/4G ED VR," it's pretty much what you'd expect: a high-performance full-frame telephoto zoom with VR effective to a claimed 5 stops. Just, you know, a stop slower than its big bro. In exchange for the slower maximum aperture, you get to shave 24 ounces off the weight, and, oh, a clean grand off the price. Yup, the 70-200mm f4 VR will run a much easier to swallow $1,399.95 when it hits shelves late next month. One catch: it won't ship with a tripod collar, and that'll cost you an extra $223.95 whenever it joins the party.
Now, you can learn all that anywhere. It's in the press release, after all. But what we at Roberts want to know is: how does it stack up? Without a full test from someone like SLR Gear we can't know for sure, but we can make some guesses from the provided MTF charts. And we now intend to.
70-200mm f4 VR @ 70mm f4
70-200mm f2.8 VR II @ 70mm f2.8
So, here are the MTF charts from the new 70-200mm f4 and the 70-200mm f2.8 VR II. For those of you who haven't read these much, I'll give you the gross over-simplification that'll probably get me banned from any future Zeiss cocktail parties (MTF charts originated thanks to Zeiss, you know). The red lines (10 lines/mm) represent the lens' contrast. The blue lines represent sharpness (and in this case that means the ability to accurately render tight detail without blurring). The higher on the graph, the better. The left side represents the center of the frame, the right side is the corners. The difference between where the red and blue lines are, and between the solid and dashed lines of the same color, help to describe how things like bokeh will work. In general, the closer they are and the more they follow the same slope, the better. When they start deviating a lot, things will look worse.
Got it? OK then! So, looking between these two we can see that at the center of the frame wide-open these lenses are basically the same. High contrast, high detail. The new 70-200mm f4 fares a bit worse as you go to the corners (especially with regards to the astigmatism there in the blue lines), but it's not until you get past the edges of a DX sensor. So, on DX it won't be an issue, and on FX it'll only realistically matter if you have a propensity for sticking your subjects in the very corners of the frames. If they're anywhere in the middle 2/3 or so of the frame, it'll be hunky-dory.
70-200mm f4 VR @ 200mm f4
70-200mm f2.8 VR II @ 200mm f2.8
Well now, here we have the opposite. At 200mm wide-open, the new lens is notably flatter than the 2.8 II is. Now, that's probably because it's already stopped down to f4, and if you tested the 70-200mm f2.8 VR III at f4 also the graph would likely look the same. But, that's sorta the point, at f4 the new lens is going to perform pretty much identically to the big bro. Except the astigmatism in the blue lines in the corners, which continue to persist. I'm not good enough with these graphs yet to say what that'll mean in the real world, but until proven otherwise I'm guessing there'll just be some softening up into the corners. All around, though, this is a pretty good show for a lens that costs a full grand less. It's obvious most of that cost savings is coming from smaller, cheaper glass elements, and not cheaper quality or engineering.
How about it? Convinced? Want to preorder one? We're here for you: http://robertscamera.com/af-s-nikkor-70-200mm-f-4g-ed-vr.html
Now, when can I get a 100-400, eh, Nikon? When do you get to make my dreams come true?
Press release after the jump.