by Klaus Schroiff, published July 2017
Introduction
You have a variety of choices when it comes to Zeiss lenses for Sony FE-mount cameras. Zeiss ZA lenses are co-developed, co-branded and marketed under the Sony umbrella. However, Zeiss is also offering several native lenses independent from the cooperation with Sony – namely the Zeiss Batis (AF) and Zeiss Loxia (manual focus) lenses. One of the most exciting of these lenses is the Zeiss Batis 18mm f/2.8 covered in this review. While the distribution channel may have changed, some things never do and the pricing falls into that category. Such ultra-wide prime lenses are never really cheap but 1500 USD/EUR is certainly on the high side. However, that’s still more affordable than the Sony FE 16-35mm f/2.8 GM and just a fraction more expensive than the slower Zeiss Vario-Tessar 16-35mm f/4 OSS.
The Batis 18mm f/2.8 is a “Distagon” which is, interestingly, an asymmetric wide-angle design that has been traditionally used for SLR lenses because it can provide some distance between the
rear-element of the lens and the sensor plane. That being said this is not really the case here. The rear element is recessed by just about a centimeter. It’s also worth mentioning that Zeiss implemented a floating system which is used to optimize the close focus performance by adjusting the distance between the groups as the lens is focused.
The quality of the construction is generally superb with a few notable exceptions. The lens body is made of metal and it maintains a constant physical length throughout the focus range. Professional and outdoor photographers will also appreciate the weather-sealing. The broad rubberized focus ring operates smoothly. So far so good … so what’s wrong? The body coating is very prone to fingerprints and scratches and the focus ring is a dust magnet. The lens looks brand new exactly once … till you remove it from the box. We’ve already seen this with the Zeiss Touit lenses. Zeiss also continues with its long tradition of providing the worst lens caps of the industry. It almost falls off just by looking at it thus better order a third-party lens cap with the lens if you decide to go for it. A deep petal-shaped lens hood is part of the package.
The Batis lens uses a linear autofocus motor which is reasonably fast and silent. Typical for most mirrorless lenses, manual focusing works “by wire” thus you are driving the internal motor by turning the focus ring. Now normally that would also translate to omitting a focus scale (because the focus ring is free floating). However, Zeiss tried something different this time – they implemented a digital OLED display that provides both distance and depth-of-field guidance in manual focus mode. The display is back-illuminated thus unlike a conventional distance-scale you can also read the numbers in the dark. Quite nice but for most users it’s probably not really more than a gimmick in real life.
As an interesting side note – according to some rumors sites (and some patent references), the Batis 18mm f/2.8 and Batis 85mm f/1.8 are actually based on Tamron designs.
| Specifications | |
|---|---|
| Optical construction | 11 elements in 10 groups inc. 2x aspherical, 5xED and 2x hybrid elements |
| Number of aperture blades | 9 (circular) |
| min. focus distance | 0.25m (1:9.5) |
| Dimensions | 95x100mm |
| Weight | 330g |
| Filter size | 77mm |
| Hood | supplied, petal-style, bayonet mount |
| Other features | Weather-sealing, OLED display, floating system |
Distortion
In numeric figures, the Batis 18mm f/2.8 shows a very low degree (1%) of distortions for an ultra-wide lens. However, a single number can’t express the realities here. Uncorrected images show a rather pronounced mustache-style distortions which can be disturbing when having straight lines in your scene. Thus if you can sacrifice a bit of quality, you should use image auto-correction.
Vignetting
Zeiss lenses tend to have at least one disease – vignetting. It just doesn’t seem to be a primary design objective in Oberkochem (Zeiss HQ). At fully open aperture there’s a very heavy amount of vignetting (~3 EV/f-stops). To be fair – this is rather normal for a full format ultra-wide lens. However, the vignetting decreases only by just more than one EV when stopping down. A minimum light fall-off of ~1.7EV (f-stops) at f/8 is certainly not something to rave about.
Enabling vignetting auto-correction solves most of the issue (unsurprisingly). You’ll still spot some vignetting at f/2.8 but it’s quite acceptable beyond.
MTF (resolution)
The Zeiss Batis 18mm f/2.8 has a highly impressive resolution characteristic. The center and near center is tack sharp at f/2.8. The border quality is also very good at fully open aperture whereas the far corners are just Ok here. Stopping down to f/4 improves the center zone even further and also lifts the corners to very good levels. The corner do still improve a little at f/5.6. Diffraction effects kicks in at f/8 and gets noticeable at f/11. That may be a little surprising but f/8 should be good enough for “infinity scenes” anyway. Avoid f/16 and beyond.
The centering quality of the tested sample was very good. Field curvature is very low for an ultra-wide lens.
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 for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations.
Chromatic Aberrations (CAs)
The Zeiss lens produces a very low amount of lateral CA (color shadows at harsh contrast transitions) starting with an average CA pixel width of 0.5px at f/2.8 and a maximum of 0.7px at f/11. This is unusually good for an ultra-wide lens.
Sample Images
Competition
There aren’t any really obvious competitors in Sony FE mount yet. The new Laowa 15mm /2 may possibly come into mind or the Voigtlander 15mm f/4.5 III. However, these are much wider and “just” manual focus lenses. Most users will probably compare the Zeiss to Sony’s gang of ultra-wide zoom lenses. Below is a size comparison to the Sony FE 12-24mm f/4 G, Zeiss Vario-Tessar 16-35mm f/4 OSS and the Sony FE 16-35mm f/2.8 GM. The Zeiss lens has one obvious advantage – it is smaller and more light-weight. While we haven’t tested the 16-35mm f/2.8 GM yet (the 12-24mm f/4 G is already in the lab), it is also very unlikely that these zoom lenses can beat the Zeiss in terms of overall quality.
Visual comparison courtesy of camerasize.com.
The Zeiss Batis 18mm f/2.8 is an excellent ultra-wide prime lens. Most of the image frame is already very sharp at fully open aperture although there is a bit of softness in the far corners. The corner softness is gone at f/4. The range between f/4 and f/5.6 is also the sweet spot where the quality is truly outstanding for a lens in this class. It may be a little surprising but you should stick to f/8 (if possible) instead of f/11 for the best quality in infinity DoF scenes because diffraction is a limiting factor already. Very low lateral CAs and marginal field curvature also contribute to the very high quality. Image distortions aren't overly pronounced but complex (mustache-style). In critical situations you may prefer to enable image auto-correction for this. That also applies to vignetting which is on the very high side (typical for Zeiss). A real differentiator is the flare resistance. You can, of course, produce a few ghostings if you push it but the Zeiss is about as good as it gets in terms of contra-light performance in this segment.
The build quality is up to professional standards - a metal body, no wobbly parts, weather sealing - but at this price level we expected no less, of course. That being said, we are not a big fan of the slippery surface coating and the dismal quality of the lens cap. The AF speed is good albeit not extremely fast but that's perfectly fine given the typical usage patterns with such a lens. Zeiss is quite proud of the new OLED display which shows you the focus distance and depth-of-field. Yes, it's nice, it's cool but the real killer argument is the image quality.
So should you buy one? We'll do some more testing of ultra-wide lenses soon but we'd be surprised to see a lens that could outperform this Zeiss lens - therefore highly recommended!
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Optical Quality
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Build Quality
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Price / Performance