Viltrox 23mm f/1.4 Lens Review 

bythom viltrox 23

What is It?

The Viltrox 23mm f/1.4 lens is one in their series of lenses in the Z-mount to feature autofocus capability. As a crop-sensor lens (DX), the fast aperture coupled with that focal range makes it a near perfect street/wide type lens (35mm effective). Nikon produced one F-mount DX, fast, prime lens (effective 50mm f/1.8), but has not done so in the Z mount. 

I was a little surprised to see that this lens was 11 elements in 10 groups, and that Viltrox has added two ED and two HR elements. At the price point and the focal length, I would have expected a simpler optical construction. Viltrox also claims nano-coating of some sort, without any specifics. 

bythom 1811

Apertures range from f/1.4 to f/16 on this lens, and a 9-blade aperture diaphragm is in place inside. You control apertures via an aperture ring, which is clickless. Apertures are marked in 1/3 stop increments on the ring. If you want the camera to choose aperture (e.g. in Shutter-Priority or Program exposure mode), you set the ring to the A position.

Close focus distance is about 12" (0.3m), which isn't very close (1:10 maximum magnification), but the focus is all internal, using a stepping motor. No DOF markings are offered. 

Up front we have a 52mm front filter thread, and Viltrox supplies a PL-11a lens hood that bayonets on the lens (and can be reversed on the lens for travel). 

While the lens is reasonably compact and appropriately DX-sized at 2.8" (72mm) long and 2.6" (65mm) in diameter, it's a robust 9.2 ounces (260g) in weight. That's the same size as the Viltrox 56mm, but slightly lighter. The weight is due to the mostly metal design and all those lens elements inside.

The lens has a built-in USB-C port for updates (of which there has been some). Price is US$300, and the lens is made in China.

Viltrox's page for the lens.

Source of the reviewed lens: B&H loaner.

How's it Handle?

This lens balances nicely on a Z50 body, and reasonably well on the Zfc body. Because our current Z DX cameras don't have sensor-VR and this lens doesn't have VR, I'd be a little more careful with this lens on the Zfc body where the lack of a hand grip might prove a problem if you're using it for impromptu street photography. Indeed, I'd recommend that you get the SmallRig hand grip for the Zfc if you're going to venture into VR-less street work with this lens.

The aperture ring is de-clicked from f/1.4 to f/16, and it doesn't have a detent at the A position, though you'll feel a "pseudo click" as you get to f/16. It's possible to have the aperture ring indicator between A and f/16 and still be in A mode. There's an abrupt change that happens when you get to the f/16 position—at least if you were at a fast aperture prior to that—so it is usually obvious when you make the transition. Still, I would have liked a lockable A position or at least a strong detent. The aperture ring is smooth in rotation, but makes a clear sound as you adjust it, so video operators beware.

The focus ring is big, easy to find, and works well with the Z50/Zfc. Indeed, manually focusing from far to a near human subject triggers the Face/Eye response in Auto-area AF as you rotate the focus ring on the Zfc. Even tap-to-focus on the Rear LCD works correctly with this lens.

The supplied plastic lens hood bayonets into place well. Build quality all around seems high on this lens, particularly for the price.

How's it Perform?

Focus: In my testing, the 23mm f/1.4 produced snappy focusing, even in low light, on both my Z50 and Zfc. Moreover, things like Face/Eye recognition work properly. I did find a few cases where my Z50 would lock onto a bright background and not revert to Face/Eye until I forced the issue, but I doubt this is a lens attribute; the Z bodies, once locked onto a background, are stubborn at letting it go. 

Focus itself is relatively silent, though there's a faint "phht" that tends to happen at focus lock in. There's minimal change of framing when going from near to far focus, a good trait for video users.

Sharpness: Center is good wide open, and improves to excellent by f/2.8. Top center performance is attained at f/2.8. From f/4 onwards, the MTF begins falling for the central area, eventually dropping back to good at f/8. Corners are a far different story. Corners are poor wide open, and clearly improve at every aperture up to f/4, where they hit what I call good. Technically, f/5.6 is the best balanced result, with center at good+ and corners nipping at good+. But if you're using this lens for things that are centered (e.g. people, street photography), I'd stick to f/2 to f/4, where the results are very good to excellent. 

I was hoping for a bit more from this lens in terms of acuity. It feels a little "old school" in that you have so much corner droop at the fast apertures. I suspect the lack of an aspherical element is the primary culprit here, as "good fast corners" are tough to design optically without one.

I thought at first that field curvature might be explaining the center/corner results, but measured field curvature is lower than I expected (present, but not the primary contributor to poor corners wide open). For what it's worth, the full frame Nikon bodies recognized the 23mm f/1.4 as a DX lens and the FX bodies set DX as the image area. 

A typical high contrast scene with deep shadows and bright highlights, both of which would tend to need adjustment. But what we're looking for is what happens on the high contrast edges:

Ignore the blur, as this area is out of the depth of field and I've enlarged it to 200% (intentionally; I was using wide aperture to see the CA). This area of the frame shows that the lens has clear longitudinal and lateral CA, though less of the latter than the former. 

Chromatic Aberration: As you'd expect from a fast lens, clear longitudinal chromatic aberration is present. Near results go slightly magenta while far goes green. Most lenses coming across my desk these days are quite good at handling lateral chromatic aberration, though. So I was surprised to see clear lateral CA at f/1.4 to f/2. By clear, I mean that it goes well beyond a pixel's width (just over 2 pixels at f/1.4). You'll want to be correcting for this in post. 

Vignetting: Surprisingly low for the fast aperture. Less than a stop-and-a-half at the corners wide open. Moreover, the imaging circle seems wide, so the corner clipping is really mostly just that. I'd say ignore the vignetting on this lens from f/2.8 onwards, even though you can't really correct it exactly in camera.

Linear Distortion: A small degree of barrel distortion, typically less than a half percent. It appears that there is some mustache to the barrel, as the distortion lessens towards the corners, and is mostly seen in the center of the frame.

Bokeh: bright edge with clear color (CA caused), but almost no visible onion skin (no aspherical lens). Wide open, cats eyes show up in the extreme corners, as does a blur complexity that isn't pretty, but the broad central area is relatively immune from both. Stopped down to f/2.8, the cats eye goes away but the aperture blades start to show slight irregularities in position, so circles don't stay circles (I see more of a tall, slight ellipse on my sample).

Final Words

Our DX lens set developing nicely now, but from a third party, not Nikon. This Viltrox 23mm f/1.4 slots right in as the street lens of choice for the Z50 and Zfc (it's 35mm effective focal length). I find it pretty much what I'd want for that task, and even for event photography on the DX bodies, though if the corners are important to you you'll need to stop down to f/2.8. Considering the US$300 price, it's somewhat a bargain. Indeed, you can now build a 13mm, 23mm, 33mm, and 56mm prime set for about US$1200 using the Viltrox autofocus lenses currently available. In FX terms, that's pretty close to 20mm, 35mm, 50mm, and 85mm. As far as I can tell from initial testing, the Viltrox f/1.4's are all similar in capability: strong central performance that needs stopping down for corner performance. 

We now have some interesting prime lens choices on the DX side: Nikon has produced a 28mm f/2.8, 40mm f/2, and 50mm f/2.8 macro lens that all fit nicely in size and weight to the DX bodies. Viltrox has produced 13mm, 23mm, 33mm, and 56mm lenses, all f/1.4, which provide low light usability and are still appropriately DX sized, though a little on the heavy side due to their all-metal construction. We still need 16mm and 18mm choices, and then we'd have a near complete set of primes to choose from.

If you haven't figured it out yet, I like this Viltrox lens. So...

Recommended (2022)

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