Nikkor AF-S 50mm f/1.8G Review


"I remixed a remix. It was back to normal" --Mitch Hedberg

What is it?
The Nikkor 50mm f/1.8G is slightly puzzling to Nikon users. It's bigger and more expensive than the lower cost 50mm f/1.8D lens it replaces, but about the same size as the Nikkor 50mm f/1.4G (see side by side image, below). Thus, people are a bit confused about what problem it solves.

It solves one big problem: it gives D3100 and D5100 (and older similar DSLRs) users autofocus on a short telephoto (for DX) prime lens that is modest in price. The 50mm f/1.8D is a fine lens, but it won't focus on the D40, D40x, D60, D3000, D3100, D5000, and D5100, so it really needed an update. On the other hand, the update produced a noticeably larger, heavier, and more expensive lens. Such is progress in the Nikon world.

Copyright 2011 Thom Hogan
f/1.8G on left, f/1.4G on right

The optical formula is dirt simple: 7 elements in 6 lens groups. One of the elements is aspherical. The filter threads do not rotate during focus. Minimum aperture, as with many of the Nikkor primes, is only f/16. Filter size is 58mm. Super Integrated Coating help keep internal reflections to a minimum. No teleconverters are recommended with this lens.

The lens covers the FX format, presenting a 47 degree angle of view (diagonally) on FX, a bit over 31 degrees on DX. Close focus is 1.5 feet (0.45m), presenting a maximum magnification of 1:6.6. The lens does not have VR and only an M/A-M switch. There's a focus scale with depth of field markings for f/16 only. It uses a rounded 7-blade aperture diaphragm which on my sample is clearly not very rounded and slightly unsymmetrical. As with all AF-S lenses, this lens will not automatically focus on a Fujifilm S1 and some film cameras. The lack of an aperture ring also makes it not optimal for many of the consumer film cameras.

Surprisingly, there's dust/moisture protection built into the mount, so it appears this may be now standard on all Nikkors, including low cost ones. The lens weighs a scant 6.6 ounces (230g), and sticks out a little less than 3" (71mm) from the mount.

The lens comes with an HB-47 hood and soft carrying glove for US$219. Nikon's page for the lens is here.

How's it Handle?
What can you say about a very simple lens? The focus ring is a bit wider than the one on the lens it replaces, and is actually quite smooth for a Nikon AF-S lens. Near to far focus happens in about a quarter rotation of the ring. No complaints here.

The HB-47 is a one-piece bayonet made of plastic; the same hood as comes with the 50mm f/1.4G. It snaps into place fine, and provides plenty of shading, especially when the lens is focused on distant subjects (the front element moves forward when focusing close).

How's it Perform?
I wish I could say it was a superb lens, but it's not. It is a better lens both in the center and especially in the corners than the 50mm f/1.8D it replaces. Significantly so, in my opinion. The f/1.4G to f/1.8G comparison is a little more interesting: the f/1.8G might beat its bigger brother in the central area (slightly off center in my sample) but the f/1.4G wins the corner battle at f/1.8. In other words, at f/1.8 to about f/2.4, it's a close battle, but the more expensive lens has more edge-to-edge consistency about it. To get to optimum results with this new lens, you need to stop all the way down to f/5.6 on DX, f/8 on FX, where it is excellent to superb from corner to corner. So the sharpness game is a mixed bag: the new f/1.8G beats its predecessor wide open, but is a step behind it's more expensive f/1.4G brother at f/1.8. (One comment about testing: focus distance makes a difference: the f/1.8G deceived me a bit by being very sharp at close distance when I first played with it in the office, but revealed it was slightly weaker at longer distances. This is one of the reasons why I don't get enamored by test charts and automated results: they're shot using a flat target that's often photographed at slightly short focus distances.)

Chromatic aberration is present, but not objectionable and easily correctable. On DX vignetting is ignorable, while on FX you might lose two-thirds of a stop at the corners. By f/4 it's ignorable. Linear distortion is low (though slightly higher than the f/1.4G) and barrel in nature. At under 0.5% it's not something I'd bother correcting unless I had software that did automatic correction based on EXIF data, in which case I'd just let that do its thing.

Nikon makes a big thing of background bokeh (quality of out of focus blur) on their site, but in actuality if the lens is stopped down even a little the blur has geometric distortion to it due to the asymmetrical aperture blades. While Nikon's own sample seems a bit better than mine, you can clearly see the asymmetry in the sample image they claim has great bokeh (it does not). Be careful with bright small highlights behind the subject when you're stopped down: they will blur out of round.

On my D3 bodies the f/1.8G seems a bit faster in focusing in low light than the f/1.4G, which I described as languid in my review of it. It's not a snap-to focus speed as with some high-end AF-S lenses, but it's a small improvement over the f/1.4G.

So the question everyone asks is this: which 50mm should I get? We've got multiple answers, unfortunately:

  • If you're going for absolute optical quality, the answer is none of the Nikkors. A few of the "normal" lenses from third parties, including Voigtlander and Zeiss, have better absolute performance. But, of course, they're manual focus lenses, and usually much more expensive.
  • DX users looking for the best autofocus solution Nikon has to offer can kind of go either way (f/1.4G or f/1.8G), as the difference isn't enough to really justify one over the other, so it's going to come down to "small corner gain at wide apertures" versus "lower price."
  • FX users have a clear winner, especially if they use the lens at the fast apertures much: they should get the more expensive 50mm f/1.4G, especially if they're shooting with a D3x. The f/1.4G hits excellent edge-to-edge at f/2.8, the f/1.8G doesn't get there until somewhere around f/5.6. (Please read that carefully. I'm not saying that f/1.4 gets you all that much compared to f/1.8, I'm saying that in the f/2 to f/4 range, the f/1.4G is the better lens for FX users. Too many people get caught up on absolute aperture, as in f/1.4 is two-thirds of a stop faster than f/1.8.)
  • If you're just looking for a dirt-cheap fast 50mm prime to use on occasion and have a body with a screw-drive focus ability, the 50mm f/1.8D is a reasonable choice if corners aren't overly important (as they often aren't when you use this for portraits on DX).

Final Word
Yes, I changed my mind a small bit from my initial impression. I hadn't really been pressing the lens when I wrote my first comments. But in looking at low light results with the D7000 and D3x, I found the new lower-cost lens is indeed slightly behind the older faster lens. For my own shooting, there's not enough difference between the f/1.4G and f/1.8G for me to have a favorite. I'm more than willing to put either on my best body and just shoot. But if I had to make a choice, it would be the f/1.8G, and simply because the focus is a bit snappier.

Recommended   review source: purchased lens
Features It's a normal prime. What features are needed?
Performance Pretty much what you'd expect. Very good, not great.
Value On the other hand, it's inexpensive for its performance.

 

Original: 8/12/2011, typo fix 8/16/2011
Ratings last updated: 8/12/2011


 

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