Well there’s no denying the 400/2.8’s are always at the top of the heap as far as sharpness and resolving power is concerned compared to the rest of the superteles. Whether that’s just because Nikon takes more care in their design, or whether it’s because the larger objective translates to a more precise registration of the image I don’t know, but with Nikon’s E series at least, the resolution differences are very small: LenScore measures the resolving power of the 600E, for example, at 1387, and the 400E at 1466, or 5.6% higher. I seriously doubt anyone could actually detect that difference in real world use.
That's a great point, Gary.
"Splitting hairs" with "which is sharper" questions ... with two lenses firmly ensconced in
excellence territory ... has dubious practical value.
The real question is what is more important to me:
extra reach or
extra light: 600mm f/4 vs. 400mm f/2.8.
Since I shoot with a D500, it must be remembered that I am shooting with an equivalent 600mm f/2.8. using a 400mm, and an equivalent 900mm f/4 using the 600.
For everyone shooting the D5, no one argues that a 600mm f/4 isn't enough reach for birding, so it should be remembered that a 400mm is really a ~600mm f/2.8 on a D500, which likewise should be plenty for birding.
While the D5 would have a high-ISO advantage, over ISO 1600, this also would be equalized somewhat with the 2-stop
light advantage of a D500 with a 400mm f/2.8. Especially since the 400 is sharpest wide-open.
(In other words, rather than crank the ISO up, like I'd have to with a D5/600 4, I would
widen my aperture. I'd have the same framing and would actually rather keep my ISO down.)
I wager that by the time you start to add TC’s of any type (unless they’ve been “tuned” to the lens such as the 800E or new 180-400), they WILL degrade the image to some extent. The other thing with TC’s I’ve found, expecially with the TC20EIII, is that while it can perform reasonably well with f2.8 lenses at close range, it will take a toll on IQ at longer distances.
Here again, though, I don't need a TC with a D500 + 400mm to equal the reach you're getting with a FX + 600mm ... I'm already there
What you say abount TCs though is absolutely true: they hold up exceedingly well when you nail the shot close (and can fill the frame or close) but they really deteriorate with distance shots that you have to crop heavily. That's my experience exactly.
Anyway, I’m not trying to talk down the fantastic 400E...I’d love to own one myself as a backup/alternate to my 600. Choosing the “right lens” always comes down to what and how you shoot. All I do know is that primarily as a birder, the 400E is not the best choice for my longest lens. I actually don’t know of a dedicated birder that uses the 400E as their longest lens, but on the other hand there are many mixed wildlife shooters that prefer the 400E for good reason too.
I would say I am more of a mixed wildlife shooter, who likes birding also.
For instance, I went whale-watching the other day, and even my 300mm (without the TC) was overkill there. I found myself in 50mm to 125mm territory more often.
Here’s a quick example of what the 600E can do....this is a 100% crop from my D850+600E taken from a distance of 90m, default NEF conversion from Capture One Pro 10, no other adjustments applied.
For reference, this is the full frame reduced to 1600 pix.
For some reason, I couldn't see your images.
Still, your points are well made and well taken.
In the end, for birding, I often find myself needing
more than 900mm reach equivalent (which I am currently getting with a 300mm w/ 2x Ext x the 1.5x D500 conversion).
Using a 1.4x on a 400mm isn't what I will be doing, I'd likely be using my 2x extender on it.
So I'd really be using either a 400mm with 2x TC (for ~1200mm f/5.6) or a 600mm with a 1.4x TC (for 12
60mm f/5.6).
I know for a fact a 2x ext. will degrade the 400mm image more so than the 1.4x will degrade the 600mm image, so I think this might be the difference, just thinking out loud here.
I would also have to buy an extra lens, if I choose the 600mm, to fill the gap between my CV 125mm Voigtländer.
To fill this gap, I am considering the 300mm f/4E PF.
In fact, I am so impressed with some of the birding images people are getting with the D500 + 300 f/4E PF combo that I may just stop there, save myself the cash, as well as the burden of the added weight when I hike.
If you take a look at
the images on this thread, the D500 + 300 f/4E PF combo produces wonderful images of even very tiny birds.
I would be delighted with this level of quality, and even
more delighted not to have to lug any kind of super-telephoto lens around anymore
Time will tell ...