Thom Hogan

It's a constant question, and particularly for me since I teach wildlife photography workshops: what Z-mount long telephoto lens should I get?

Buried in that question are three factors that need to be considered: (1) budget; (2) quality; and (3) handling (size/weight). I constantly get the "yeah I'd get that except for X" response to my suggestions, and X tends to always be #1, #2, or #3.

So let me try a different approach. You need something that gets you to 400mm, 500mm, or 600mm. We'll look at just those options. Why? Because if you don't need at least 400mm, you're not playing the game (;~), and if you need more than 600mm, then you don't currently have a choices that don't involve a teleconverter.

I'm going to tackle this by splitting the lenses into three budget groups: inexpensive, moderately priced, and expensive. I'll use list prices, even though we have some fairly hefty discounts in play at the moment. I'll also put the lenses in price order.

Here goes:

Inexpensive

• Tamron 150-500mm f/5-6.7 VC — US$1200. On the large side, a little slower than most Nikkor options, optically very good (review coming). 
• Tamron 50-400mm f/4.5-6.3 VC — US$1300. More compact travel size, optically excellent, focuses close (review coming).
• Nikon 28-400mm f/4-8 VR — US$1300. Smallest of the bunch for travel, but slowest of the lenses; surprisingly good optics, though you border on diffraction impacts and have to watch shutter speeds/camera handling at 400mm. 
• Nikon 180-600mm f/5.6-6.3 VR — US$1900. On the large side, no real extra controls, with arguably best in class optics at 400mm.
• Nikon 100-400mm f/4.5-5.6 VR S — US$2700. Now you see why I down-graded my recommendation from Highly Recommended to just Recommended: Nice size, with good extra controls, but doesn't provide better optics for the extra money. Does focus close, though. 

Moderately Priced

• 400mm f/4.5 VR S — US$3300. If you can live with the fixed focal length, this lens has almost everything: compact and light, excellent controls, reasonably fast aperture, and excellent optics. 
• 600mm f/6.3 VR S — US$4800. Compact and light for the focal length, excellent controls, and excellent optics. 

Expensive

• 400mm f/2.8 TC VR S — US$14000. Big and heavy (in comparison to above), but top-of-the-line at everything else. Best optical choice, and clearly so. Built-in teleconverter is a huge sweetener.
• 600mm f/4 TC VR S — US$15500. Big and heavy (in comparison to above), but top-of-the-line at everything else. Best optical choice, and clearly so.  Built-in teleconverter is a huge sweetener.

So here's my advice:

1. Choose in the highest budget class you can afford. 
2. Within that class, consider only the focal length you truly need.
3. Pick the best lens optically, or pick the smallest/lightest lens; there is no "both." 

Here's where I'll get pushback: "but Thom, I need a zoom." Great, then you've picked the Inexpensive class of lenses, so just pick the best one for you. Right now that's likely to be the Tamron 50-400mm, Nikon 180-600mm, or Nikon 100-400mm. 

"But Thom, how does it handle teleconverters?" Oh, you picked the Moderately Priced group, then, as the Inexpensive lenses either don't support a teleconverter or don't do so well with them. Good news: Both the 400mm f/4.5 and 600mm f/6.3 work really nicely with the Nikon 1.4x teleconverter. 

"But Thom, I can't afford the expensive TC lenses and I seek the best." You once again picked the Moderately Priced group ;~). You'd be surprised at how well those two moderately priced lenses do. Yes, you've lost some light gathering and background separation. If you need more of those things than the 400mm f/4.5 and 600mm f/6.3 provide, well, by definition you've put yourself in the "price of a decent used car" territory. Rent the lens if you don't need it all the time. Or start saving up for it.

Now, with that said, I can say I've used every one of the above options at one time or another, and I've been pleased with the results. As I've noted before, the Tamron 50-400mm or the Nikon 28-400mm are excellent long telephoto choices with a Z50II. Surprisingly excellent.

You can get yourself all tied in knots by trying to analyze every last nuance and come up with the "best" solution. I'd defy you to tell me which lens I used on any image I've taken with all the above. We live in a world of Very Good Choices. Choose wisely.

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So, did you figure out what lens I used on the above image? Hint: it wasn't my usual 400mm f/2.8 TC VR S.

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Bonus: Just before I posted this article I noticed a couple of comparisons in Internet fora that try to get to "what looks best" between some long telephoto lens choices. This is far trickier than you might think. For instance:

• Between best case (f/2.8) and worst case (f/8), there's a potential for three stops slower shutter speed (or higher ISO). Longer shutter speeds will tend to alias edges compared to higher ones. Higher ISO values will put noise into the mix, and noise reduction may not produce strong edges.
• Likewise, body can make a difference: a Z50II doesn't have sensor VR and thus also doesn't have Synchro VR. Like the previous item, this can begin aliasing edges if you haven't nailed handling and shutter speed.
• Comparing the same final cropped size of an animal between 400mm and 600mm will tend to always make the 400mm lens look worse.
• At 20mp DX and 45mp FX, f/8 is right at the diffraction impact start. While I don't generally call that "diffraction limited" I almost always measure a lower overall MTF at f/8 than I do at f/6.3 with these telephoto lenses. Note that even a 1.4x teleconverter puts you beyond f/8 with f/6.3 lenses. 
• The inexpensive lenses all have a tendency to lose some overall contrast maxed out (aperture, focal length) compared to the more expensive ones. Careful post processing can help make an inexpensive lens perform visually better.

In case you haven't figured it out, Step #1 is a critical one. If all you can afford is the inexpensive class, you're going to be compromising in some way.