Recently, we reviewed the Viltrox AF 85mm f/2 EVO, and it turned out to be probably the best value prime in its segment. Viltrox didn’t stop there, and they’ve just released the Viltrox AF 55mm f/1.8 EVO – both in Sony E- and Nikon Z-mount. The EVO lenses sit between their PRO and AIR lenses. In many ways they are more related to the PRO lineup except for the more moderate speed. Compared to the AF 85mm f/2, Viltrox is going for a higher price at 370 USD / 429 EUR / 359 GBP / 539 CAD / 68,400 JPY, which is still fairly moderate in the grand scheme of things. The increased price tag may relate to the claim that this is an APO design, which corrects for both axial and lateral CAs. This is also marked as such on the front of the lens (AF 55mm f/1.8 STM ASPH ED IF -APO-).
The build quality is, once again, impressively high. The lens body is made of metal, including the very smooth focus ring and the de-clickable aperture ring. It also features a very clicky customizable Fn-button. In terms of weather-sealing, there’s just a mount gasket. A petal-shaped lens hood is part of the package.
The 55mm f/1.8 uses an STM motor for internal focusing – thus the lens does not extend during focus operations. While this isn’t the latest and greatest motor type, it works fine regarding both speed and quietness.
| Specifications | |
|---|---|
| Optical construction | 13 elements in 9 groups (1x aspherical, 2x ED, 2x HR) |
| Number of aperture blades | 9 |
| min. focus distance | 0.43m (max magnification: 0.1x) |
| Dimensions | φ69 × 78mm |
| Weight | 385g |
| Filter size | φ58mm |
| Hood | petal-shaped (bayonet mount, supplied) |
| Other features | Aperture ring (de-clickable) Fn custom button Firmware updates via USB-C/Bluetooth Mount gasket |
Distortions
The lens produces a native image distortion of ~0.2% pincushion-style. This is very low and not an issue. Curiously, we detected that auto-correction made things a little worse with a pincushion distortion of 0.7% (yes, we cross-verified this again). Possibly related to the specific focus distance that we use for testing this (?). It’s the first time that we’ve noticed such a characteristic.
Vignetting
The vignetting characteristic is about average in RAW images. At f/1.8, there’s a very noticeable light falloff of 2.4 EV (f-stops). This has eased substantially at f/2.8, and the issue is mostly gone at medium aperture settings.
Vignetting autocorrection reduces the issue by more than 1 EV (f-stop) at f/1.8, and the vignetting is almost negligible from f/2.2 already.
MTF (resolution) at 45 megapixels
The Viltrox AF 55mm f/1.8 EVO produced excellent resolution results in the lab. The broader center is downright superb at f/1.8 already, and the outer image field is easily very good. Stopping down to f/2.8 raises the bar further. The image center easily exceeds the resolution of the 45 MP sensor, and the border quality is now also excellent. The peak performance is reached at f/4 with superb quality across the image field. Diffraction effects set it beyond f/5.6. f/8 still provides very good quality. At f/11, the quality is more impacted – as usual.
The centering quality of the tested sample was good. The field curvature is flat.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH), which can be taken as a measure of sharpness. If you are keen to know more about the MTF50 figures, you may check out the corresponding Imatest Explanations.
Chromatic Aberrations (CAs)
Lateral CAs are very low at all aperture settings, even without corrective measures.
Bokeh
The 55mm f/1.8 may not be exceedingly fast for a standard prime lens, but it’s still fast enough for creating a bokeh effect in many scenarios, so let’s check it out.
Out-of-focus highlights aren’t perfectly rendered but still pretty good overall. If you look (very) closely, you may notice a very slight onion-like substructure in the inner zone of the discs – probably due to the aspherical element. The outlining of the discs is marginal, and the discs remain circular up to f/2.8 – at least in the image center. Very slight edginess from the aperture shape creeps in at f/4.
When looking at the rendering at f/1.8 across the whole image field, we can observe that the circular shape is maintained in the broader image center. The discs deteriorate from the mid-field, with “cat eyes” visible in the corners. As usual, the zone with circular discs broadens when stopping down. The corner discs are mostly restored by f/2.8.
The blur in the focus transition zone is a bit nervous – possibly because the lens is so sharp and contrasty even at maximum aperture. The less important foreground is rather harshly rendered.
Bokeh Fringing / LoCA
LoCAs, or bokeh fringing, is a color fringing effect on the Z-axis. It shows up with a purplish tint in front of the focus point and a greenish tint behind – and it’s nearly impossible to fully correct in post.
So this chapter is an interesting one because Viltrox claims that the 55mm f/1.8 is an APO lens. As you can see below, there’s just a hint of color fringing, so we’d mostly agree with the claim.
You may notice that the focus point moves towards the rear when stopping down. This focus shift is called “residual spherical aberration” (RSA). However, due to the increased depth of field, the initial focus point remains sharp; thus, this isn’t of any practical relevance.
Sun Stars
Usually, we don’t test for sunstars at this focal length, but while we were also testing the 35mm f/1.8 EVO, we added it this time. Sunstars are caused by diffraction spikes at the edge where two aperture blades meet.
At f/1.8, the aperture is perfectly circular, so strong lights (here an LED) are just rendered as a blob with a bit of haze. At f/2.8, the first rays are showing up. However, for the best results, you should stop down to at least f/8. The rays are nicely spiky. The 9 aperture blades create 18 rays, which is a bit much. However, you can only choose between nice out-of-focus highlights or fewer sun stars, but not have both.
Competition
We are seeing more and more 50s available in Nikon Z-mount (and Sony E-mount anyway). In Z mount, the most obvious competitor is the Nikkor Z 50mm f/1.8 S. Surprisingly, the Viltrox lens can easily match the quality while being $200 (EUR) more affordable. In fact, it produces far fewer axial CAs. The Nikkor may have a slight edge regarding the bokeh.
Nikon is also offering a “classic” nifty fifty, the Z 50mm f/1.4, in a similar price bracket as the Z 50mm f/1.8 S. However, don’t expect a better formal performance. It’s “just” faster with a more classic bokeh concept (more dreamy).
And then there are the usual suspects of the more exotic Chinese players, such as Meike, 7Artisans, and Yongnuo. There’s also an old Viltrox AF 50mm f/1.8, which should not be mistaken for the 55mm f/1.8 EVO. Unless you are on a very tight budget, these are probably not worth it.
Sample Images
The Viltrox AF 55mm f/1.8 EVO Z delivers an almost shockingly high performance in our tests. The sharpness (contrast and resolution) is about as good as it gets in this lens class. Viltrox also has a special treat with this lens - an APO design - resulting in much reduced axial CAs which are plaguing many other fast 50s. Lateral CAs are also minimal. There is some native vignetting, which is nicely handled via auto-correction. Image distortions are a bit odd. They are very low in RAW files, but auto-correction makes things a little worse - at least at the focus distance that we use for testing. It's nothing to get headaches about, though. The quality of the bokeh is a bit of a mixed bag. Out-of-focus highlights are generally nicely rendered, but the blur quality can be a bit too contrasty in certain scenes.
The build quality is impressively high for the price as well. The lens is tightly assembled based on a metal body. Viltrox also added a basic mount sealing, at least. The AF is reliable and "fast enough" for such a lens.
Quality comes at a price - also in China - so the price tag isn't rock bottom for a fifty. However, given the performance, it's still a bargain.
The Viltrox AF 55mm f/1.8 EVO can be purchased via Viltrox Store (the first batch is 5% off) or via the usual suspects such as Amazon, Adorama, or B&H.
The Good
- Extremely sharp
- Great value
- Impressive build quality
- (almost) APO at a budget!
The Bad
- Bokeh can be a bit harsh in high contrast scenes
- Max magnification of 0.1x isn't overly impressive
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Optical Quality9
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Build Quality8
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Price / Performance10