Nikon 40mm f/2.8 Micro-Nikkor DX Lens Review

bythom nikon 40mm

What is It?
It seems strange that one of the few lenses that Nikon actually scaled for DX is the 60mm Micro-Nikkor, but that's exactly what we have here. I suspect Nikon's thinking is that "it's a normal lens, but it's also a macro lens."

But is it worth getting it for either function? We have an arguably better "normal" lens in the 35mm f/1.8G DX. And here's the problem with the macro side: at 1:1 close focus, you're got about 1" of working distance (from front of lens to subject), which means that the lens will be blocking most light from the subject.

So right up front I have issues with why this lens even exists. I can't see a real audience for it.

Like all the current Micro-Nikkors, this lens gets down to 1:1 (lifesize). That means objects at close focus are recorded the same size as they exist in nature. Given that the DX sensor size is about 24mm wide, that means if you focus on a 24mm-sized object at the closest focus distance, your object comes out filling the frame.

Which leads me to an aside: some Web sources incorrectly write that a 1:1 lens gets 1.5:1 reproduction on a DX/APS body. Nope. 1:1 is 1:1. At 1:1 an object is rendered at it's actual size. Of course, if you had a 36mm object that rendered at 1:1 and full frame on an FX body, you would end up with a crop of that object in DX. But 24mm of the object would be recorded across the 24mm width of the DX sensor (leaving off 12mm: "the crop").

One nice thing about the 40mm Micro-Nikkor is that it has higher end attributes. Specifically, AF-S that can be overridden from the focus ring (M/A), and a focus limiting switch (full range or 0.2m to infinity. The odd thing about the limiting switch is how close it is to the full range (0.2m versus 0.163m). After playing with the lens for awhile, I think the reasoning must be this: with full range there's a good chance you'll be banging things against the front lens element as you try to handhold your way to 1:1. With the limit switch set, you run out of focus with a little extra breathing room.

Other things you might want to know about the lens: 7-blade aperture diaphragm in a 9 element, 7 group design. The filter ring doesn't rotate during focus, is a svelte 2.7" (68.5mm) long and weighs in at 8.2 ounces (235g).

There's a focus distance scale, but no markings for DOF or IR. Like all ED lenses, you can set manual focus positions beyond infinity.

The lens uses 52mm filters and is made in China. Price is US$280 and comes with an HB-61 lens hood.

Nikon's Web page for the lens

Data page for the lens

Source of the reviewed lens: purchased (eventually sold)

How's it Handle?
The focus ring is a reasonable size near the front of the lens. On my sample this ring actually feels well coupled to the focus mechanism and very smooth and precise for a low end lens. That's probably because this isn't an internal focus lens: we're moving the front of the lens system forward as we focus closer, and more than likely this lens has a traditional mechanically linked cam to do so. Whatever the reason, this is about as good it gets on low-cost lenses in terms of focusing control. The full range from 1:1 to infinity is about a half turn of the ring.

In terms of overall size, the lens is significantly smaller and lighter than even the 60mm Micro-Nikkor it mimics, which shows that DX can produce smaller lenses. However, note that at close focus the front of the lens extends about three-quarters of inch forward.

Working distance, as noted before, at 1:1 is abyssmal, barely breaking 1" (3cm), which is a very short distance and one that will prove difficult to get most subjects well lit with.

Another aside: working distance is the distance from the front lens element to the subject at 1:1 (or whatever the maximum reproduction ratio is for the lens). When working distances get too short, it's hard to light (or keep from shading) your subject, and insects will easily spook.

How's it Perform?

Autofocus: No real troubles here. The only sluggishness is when you go from 1:1 to a longer focus distance, in which case there's a clear slowdown. If you want to preserve the fastest focus ability, use the limiter switch set to 0.2m to infinity. It's clearly that last move from 8" to closest focus at around 6.5" that is causing the longer focus times on a close-to-far focus pull.

Sharpness: I have to admit to being disappointed. If perhaps this were an exceptional all-around performer, I might not be so hard on the 40mm focal length. Unfortunately, it's not. Central performance is pretty much excellent out to f/8, with f/5.6 being the peak. On any of the consumer DX cameras, the center section is fine.

It's the edges where my disappointment comes, as they never make it to excellent. They start out fairly weak at f/2.8 and also peak at f/5.6, but they never come close to matching the center performance. So corners will always be softer than the center on this lens, and significantly so wide open.

Close up, things improve a bit, with the corners looking closer to the center performance on my sample at f/4 and up.

Vignetting: A full stop of vignetting at normal distances and f/2.8, a half stop at f/4, and a quarter stop from f/5.6 out. This actually improves at close focus; at about 7" the lens has ignorable vignetting right up to the close focus mark. Of course, your subject is shaded by the lens at that point, but that's a different story (let me tell you, trying to come up with a lighting arrangement to test this without producing flare was not easy).

Chromatic aberration: A curious but good performance. Chromatic aberration rises from ignorable to minimal as you stop down. What little there is corrected by most Nikon DSLR bodies these days for JPEGs, and is easily fixed in raw converters, as well. Worst case production on my D7000 was about 1.5 pixels in the extreme corners at f/22, less than three pixels on a D7200. On the other hand, longitudinal chromatic aberration was fairly high, with purple front and green fringing highly evident.

Flare: The front element is inset, and the supplied hood is deep enough to reinforce that well, so contrast was high and flare low except for high intensity lights in the scene. Even then it was well controlled.

Distortion: I'm not entirely sure there is any. Certainly none worth mentioning Imatest tells me that there is about .1% of pincushion, but we're down in the realm where it simply isn't visible and probably not worth spending time correcting.

Bokeh: The longitudinal chromatic aberration puts colored rings on bright highlights. The seven-blade aperture is misshapen and highly oblong (vertically) on my sample, which tends to add a bit of mishappeness to those same highlights. In terms of focus-induced blur, that seems to be fairly regular. So blurred backgrounds look okay, but highlights in the background that are blurred look irregular. Not a great bokeh performance, but not unlike a lot of Nikkor primes these days.

Final Words
We've got two areas to cover here in the wrap-up:

Macro: As a macro lens, I don't get the functionality. You really aren't going to go down to 1:1 with this lens very often, as the working distance just gets in your way. On the other hand, if you're a quasi-macro person, where you just want to get closer than your regular lens can get you (say 8"), then maybe you'll find this lens useful. Personally, I don't. I like the longer working distance and perspective the 85mm or 105mm would give you on a DX body.

Aside: The original Micro-Nikkors were 55mm and designed for a certain purpose: copying flat art on copy stands. You often didn't take them to 1:1, and if you did, you were in a controlled lighting environment. The real thing of interest on those original Micro-Nikkors wasn't the 1:1 ability, it was the flat field correction (CRC as Nikon called it). Somehow, the 55mm focal length became 60mm and the emphasis on flat field correction lessened, but we stuck with the focal length and 1:1 ability. Most people using maco in the field gravitated to the 105mm or 200mm Micro-Nikkors because of the working distance, yet Nikon kept iterating the 60mm as if it were the right answer to something. I'm still trying to truly find what it's the right answer to, and the 40mm DX version is even harder to figure out, as it's working distance is as little as I've seen on a macro lens other than some speciality 5x lifesize lenses. Even the 60mm non-DX Micro-Nikkor seems a slightly better choice for DX users to me than the 40mm.

General Purpose: The existence of the 35mm f/1.8G is all you need to know: it's the better choice, by far, for general work in the "normal" focal length range.

Drawbacks

  • Longitudinal CA. Why is your nose more purple than your green ears?
  • No Working Distance. At 1:1 you're right on top of your subject, literally.

Positives

  • Good build for the price. Nice focus ring, reasonably well made.

Other Notes:

The 40mm lens has limitations you need to be aware of:

  • Converters: no converters are recommended.
  • G: Since this is a DX lens, it's not likely that you'd mount it on an older 35mm body that can't handle the lack of aperture ring or makes restrictions because it is missing.
  • Coverage Area: covers the full FX frame from 10' inward, but black corners appear as you focus towards infinity.

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