|
Viltrox AF 16mm f/1.8 FE - Review / Test Report |
|
Lens Reviews -
Sony Alpha (Full Format)
|
|
Page 1 of 2
Review by Klaus Schroiff, published June 2023
Introduction
Many of us know the problem - sometimes wide and fast just isn't wide and fast enough. And then there's the other problem - the wider and faster you go, the more you are entering stratospheric price levels. However, there might be a solution to these problems - meet the Viltrox AF 16mm f/1.8 FE, available in Sony E-mount and, soon, in Nikon Z-mount. Yes, there are wider and faster lenses, but the Viltrox lens keeps a nice balance by offering a little extra without going downright bonkers. And it does so without breaking your bank account at just 549 USD - that's less than half (!) of what you have to pay for Sony's own FE 14mm f/1.8 GM. With a weight of 550g, it isn't a burden in your bag either. This sounds too good to be true then? Let's find out.
Viltrox didn't cut corners regarding the build quality of the AF 16mm f/1.8 FE. The lens barrel is made of metal, including the mount and the smoothly turning focus ring. Even the back part of the supplied petal-shaped lens hood has a metal ring instead of being all plastic. The length remains constant throughout the focus range. On top of that, it also features dust-proof sealings - 6 of them, to be precise. They also implemented a dedicated aperture ring which can be set to click or clickless mode. Moreover, there are 2 custom buttons (Fn1, Fn2) that can be configured on certain Sony cameras. Another interesting feature is the LCD display. It's not a first - we have seen this on Zeiss Batis lenses before - but this one shows some more information, including distance, focus distance limiter settings and the current aperture. A depth-of-field indicator would have been nice - possibly something for a firmware update (possible via a USB-C port)? Unlike some of its distant cousins, the Viltrox AF 16mm f/1.8 FE doesn't have a bulb-like front element, and it accepts 77mm front filters.
Some of the other Chinese players are still struggling to source autofocus motors for their lenses, but Viltrox solved this quite a while ago already. The lens has a noiseless stepping motor (STM) which is reasonably fast. As usual, manual focusing works "by-wire," which is well implemented. Focus breathing is all but absent, so that's good news for videos.
| Specifications |
|---|
| Optical construction | 15 elements in 12 groups, incl. 4xED and 3 aspherical elements |
| Number of aperture blades | 9 |
| min. focus distance | 0.27m (max. 1:10 magnification) |
| Dimensions | φ85.2x103mm |
| Weight | 550g |
| Filter size | 77mm |
| Hood | petal-shaped (bayonet mount, supplied) |
| Available Mounts | Sony FE, Nikon Z (soon) |
| Other features | LCD display, 2 custom buttons, clickless aperture mode, dust-sealing, aperture ring |
Distortions
One of the really surprising aspects of the Viltrox AF 16mm f/1.8 FE, and there are a couple, is the distortion characteristic. Namely, it's basically distortion-free - even in RAW images. Auto-correction with its lossy side effects isn't needed.
Vignetting
Ultra-wide lenses produce quite a bit of vignetting at large aperture settings, and the Viltrox lens is no exception to the rule here. In RAW images, the light falloff exceeds 3 EV (f-stops). It's not quite as much at ~2 EV with activated auto-correction. At medium aperture settings, the vignetting decreases to ~0.6EV (auto-corrected), which isn't disturbing anymore.
MTF (resolution) at 42 megapixels
Many ultra-wide lenses struggle when it comes to maintaining a high resolution across the image field, but the Viltrox is, once again, surprisingly performant. The image center is already excellent at f/1.8, with the near center following with very good results. The borders are still good to very good here, and even the corners maintain good levels. The outer image field reaches very good quality from f/2.8, with impressive peak results reached at f/5.6. Diffraction kicks in at f/8. As usual, aperture settings beyond f/11 should be avoided - this is a physical limitation.
The centering quality of the tested sample was Ok. The field curvature is low.
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 want to know more about the MTF50 figures, you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Lateral CAs are low, with a peak CA pixel width of ~0.6px at the image borders.
Bokeh
The Viltrox AF 16mm f/1.8 FE is a fast lens allowing for some decent object isolation at closer focus distances at least. Thus let's have a look at the quality of the bokeh.
Wide- and more so ultra-wide lenses rely heavily on aspherical elements in their design. These elements can minimize image distortions and improve image quality in the outer image field. But usually, they also come at a price - out-of-focus highlights tend to be busy. The Viltrox lens does a reasonably good job for a lens in this class. However, as you can see below, there's some strong outlining visible at f/1.8 combined with mild onion rings in the inner zone. Stopping down to f/2.8 results in more edgy discs, and the imperfections within the inner discs are getting more pronounced.
Our standard bokeh testing procedure doesn't work with ultra-wide lenses, but let's simply look at some real-world results. Below are two image crops illustrating the quality of the background blur.
While not perfect, the AF 16mm f/1.8 FE handles these situations quite well, even with a busy background.
Bokeh Fringing / LoCA
Boheh fringing/LoCA is an axial color fringing effect with purplish halos in front of the focus point and greenish beyond. The Viltrox AF 16mm f/1.8 FE keeps the fringing at a minimum. There are traces visible at f/1.8, but they are mostly gone at f/2.2 already.
Sun Stars (Experimental)
Below is s sequence of 100% cropped images from 20mm f/4 all the way up to f/16 - illustrating the sun star behavior. Sun stars are an aperture effect that shows up if a bright light source is part of the scene (usually in night shots). Below are some crops of a strong light source taken across the relevant aperture range. Due to the circular aperture shape, the sun stars are non-existent at f/1.8 and f/2.8. They start to emerge at f/4are getting more pronounced at f/4, with the best results achieved between f/8 and f/16.
Flare
Determining whether a lens is prone to flare is a tricky topic. If you push it, you can force all lenses into producing some flare artifacts. Artificial testing scenarios aren't really all that useful here. You won't really take an extreme shot like the one below in the first place. So yes, you can also push the Viltrox lens into producing some ghosting, but it's nothing out of the ordinary, really.
|
|
