In this article I will compare two high quality wide angle lenses for Sony full frame cameras (A7 and A9 series): the Tamron 17-28mm F/2.8 Di III RXD and the Batis 18mm f/2.8.
We will consider all the aspects, from the build quality to focusing and, above all, the optical quality (not just sharpness) with a lot of real shots to see the differences in reality and help who is looking for a great and fast wide angle in the 16-20 mm focal range for his/her Sony full frame, to choose the best model. Let's anticipate that both ones are very good, priced around 1000 €/$ (with taxes) for the Tamron and 1300 €/$ for the Batis. Of course the comparison will be done with the Tamron at 18mm focal length.
Here are the two wide angle lenses side by side (click to enlarge).
The Tamron has a more "elongated shape" (diameter 7.3 cm and length 9.9 cm) while the Batis is shorter but larger (max diameter 10 cm and length 8 cm). Both ones are not heavy being full frame fast (f2.8) wide lenses, they are even in the lighter range. The Batis' weigth at 330 gr is 90 gr lighter than Tamron at 420 gr, though from the form factor one might guess the opposite.
The build material is high quality plastic with metal mount (of course).
Regarding controls, both provide the manual focusing ring (we'll talk of it later on), the Tamron of course also the zoom ring that is in front of the focus ring. None of these lenses unfortunately have other controls, like the AF/MF switch (that can be set on the camera) or a configurable ring.
The Batis offers a little LCD display (so far just Zeiss on some Batis lenses has added such a device on a lens) that is visible also in the dark. The LCD shows current focus distance and depth of field, useful especially when using manual focus, we'll comment it in the Focus section.
Both lenses are weather sealed, for dust and humidity/light rain. The level of tropicalization is not declared and since testing it would risk to ruin the lenses, we trust the "sealed" statement, unless someone wants to try to put them under pouring rain at his/her risk ????.
Both lenses are sold with a hood that is not fixed (can be mounted and removed) and with front threading to mount a filter, with a 67mm diameter for Tamron and 77mm for Batis (the latter costs a bit more).
None of the lenses provide optical image stabilization, though recent Sony cameras do provide in-body stabilization and lens stabilization is mainly required for long focals (tele lenses).
A secondary note: the Batis lens cap is really of "basic" quality - it seems not to be very durable and firmly attachable to the lens, it's a pity for an expensive lens, better to buy a third party one as soon as you get this lens.
Summary: two quite equivalent models, with the obvious difference of one being a prime and the other a zoom.
Focal range and 17mm vs 18 mm
Is the difference between 17mm (Tamron) and 18mm (Batis) clearly visible or useful? Yes, there is a noticeable difference and probably the Tamron is a little bit wider than 17mm or the Batis is a little bit longer than 18mm, let's see with an example how much the field of view of the Tamron is larger than the 18mm of the Batis:
The difference is well visible and the Tamron also can be zoomed from 17mm to 28mm: not a typical focal range, like more classic 16-35 or 17-40, it is narrower to keep dimensions and weight down, but definitely more flexible than a prime.
Summary: more flexibility in focal range for Tamron than for Batis.
The Auto Focus is snappy and precise in both models and, above all, silent, so friendly to videomakers without the hassle of the focusing noise.
Out of some hundreds of shots done for this comparison, a couple of ones with the Tamron resulted out of focus while one with the Batis was not spot on focus. Thus optimal performances, though in one of the out of focus situations the Tamron didn't really want to focus and it might be a specific condition that will be solved via a firmware update like it happened with the Tamron 28-75 that has been improved in AF with updates.
About Manual Focus things are different: like in almost all AF lenses for mirrorless cameras, focusing is indirect, so called "focus by wire" - turning the focus ring does not move any lens but transmits an electric signal to the camera that itself send commands to move the lenses. This indirect transmission, that presents some advantages in lens design, makes manual focusing more difficult, also because typically the speed with which you turn the ring changes the speed of lens movement: it may be useful for some still shots since you can quickly go from close to far focus (or the opposite) with a quick and short movement of the ring, but the focusing becomes less precise and not reproducible - there is no fix position for the focus ring with respect to a certain focus distance. This is typical a problem for professional video shooters that use follow focus. Some recent lenses are provided with linear manual focus ring, where speed of ring turn does not change focus speed, but it's not the case for the Tamron neither for the Batis.
Back to Manual Focus with these lenses, the magnification function in the camera is fundamental for good focusing, though the focus by wire can make very precise focusing a bit challenging.
The Batis offers the LCD display that in case of MF will show focus distance and depth of field. Doing some tests I suggest not to rely on it for an absolute precision: sometimes a very little turn of the focus ring does change focus distance but the LCD shows the same value, so better always to check focus with the viewfinder.
Summary: performances on a par, not the best Manual Focus for video.
Both models employ several lenses as wide angle design: 13 lenses in the Tamron and 11 in the Batis (the latter is a prime so in general it needs less elements), with a lot of special elements, a clear indication of the search for maximum reduction of typical optical flaws.
In particular, the Tamron includes 3 aspherical elements (that contribute to reduce aberrations while making the bokeh a little more "nervous") and 3 elements with low or ultra low dispersion.
The Batis includes even 4 aspherical elements and 5 with abnormal partial dispersion to reduce aberrations so 9 lenses out of 11 are specialized. From the optical scheme and since it is a prime, from the Batis we expect the maximum quality. Let's go and see.
Both models show barrel distorsion, with some "mustache" waves, that are automatically corrected in camera for video (important) and in JPG, with a cleaner result in the Batis, while in the Tamron, that has natively a stronger distorsion, you can see some slight distorsion left after correction.
Current versions of Adobe Lightroom 8 and Capture One 12 include the correction profile for the RAW of the Batis while not yet for the Tamron that is a very new lens, but it will arrive soon for sure. In any case, especially the Tamron is not the ideal lens for architectural shots where you want perfect straight lines.
The following image is from a close up shot with the classic wall to show the distorsion on the RAW before and after the correction in Lightroom 8 - for the Tamron I used the correction of its brother Tamron 28-75 f2.8 that does already a good job for the wide position, waiting for the official profile.
The Tamron, being a zoom, after 17-18 mm and towards 28 mm changes its distorsion into the typical cushion form, as expected. Here using the Tamron 28-75 f2.8 profile correction does not do a good job, you need to wait for inclusion in your RAW editor of choice. Update 12 February 2020: Lightroom 9.2 finally includes profile correction for the Tamrow as well and does a good job.
Summary: distorsion is not the strong point of these lenses, but better the Batis.
Vignetting at 17/18 mm is quite strong, not unexpected for (super)wide angles relatively fast (f2.8). Here the extreme corners are as dark as about -2.5/-3.0 EV, so natively very dark. The Batis is slightly better than the Tamron by about 0.2 EV but the differences are hardly visible in practical use.
Also for vignetting, we are helped by the in-camera correction or by post processing for RAW and results are acceptable.
In both models there is a very slight tendency to a greenish tone in the extreme angles where vignetting takes place, it can be seen pushing color saturation very high: see below where saturation in Lightroom has been set to an abnormal value of +100 (so in normal usage the effect is much much less visible).
Stopping down the aperture to f4 and f5.6, vignetting is reduced though it does not disappear completely, but, as said, with the software correction not a lot to worry about.
Summary: performances on a par (slightly better the Batis but almost not noticeable).
Sharpness and micro-contrast
Let's now examine the sharpness and micro contrast with detailed comparison for far focusing subjects, since tipically a wide angle is used for this type of shots.
- Sony A7III camera with 24 megapixels;
- preliminary verification of each lens centering, from which a good centering has been verified with the samples used for this comparison, but with a softer corner in the Batis (upper right) that has not been used for comparisons and a very slightly less sharp side (left) in the Tamron. Almost no lens is really 100.00% perfect!
- Shots on a tripod with timer to avoid shaking
- 2 shots with Auto Focus for each tests with good scene light, selection of the best out of the two;
- comparison of shots at 100% or more.
The following images are the comparisons at the same focal legth of 17mm (the Tamron actually measures sometimes 19mm to match Batis 18mm) at full aperture of f2.8.
The center is super sharp and very contrasty in both models, really exceptional results.
Extreme corners, the weak area of every lens, are good to be at full aperture, the Tamron is even a tad sharper.
Stopping down to f4, the center was already exceptional, corners improve and now the Batis takes the lead from the Tamron. Both images are exactly in the extreme corner so very good performances for both ones.
Let's check also the details in the upper edge of the image where the Batis has a very slight advantage over the Tamron as micro-contrast/colors (e.g. the roof around the chimney).
At f5.6 still a bit of improvement in the great center, where Tamron may be even sharper, corners are very good at f5.6 - in the following shot the Batis does not come out at its best (maybe not perfect focus like Tamron in this example), infact there is no visibile improvement over the image at f4.
At f8 the sharpness does not improve anymore, rather it start softly decreasing both in the center and in the corners (probably an initial effect of diffraction that becomes more pronounced by f11). The sweet spot for both lenses is around f/5.6.
Regarding near subjects, performances on the corners are not great as for far subjects (much better like this than the reverse since these are not lenses for macro but for landscapes). Extreme corners do have a significant drop in sharpness and micro contrast at full aperture, stopping down the situation improves but not at the levels of far subjects especially for the Tamron.
However Tamron has a different advantage over the Batis: maximum magnification is 0.19x (the subject can be focused as close as about 8 cm from the front lens) while Batis stops at 0.11x so with the Tamron it is possible to do close-up shots - to achieve best results (sharpness/contrast) in close-ups it is necessary to stop down to f4. Let's see an example of a bank note of 20 euros at a few centimeters from the front of the Tamron.
With the Batis you can go no much further than this magnification:
Let's examine now main aberrations (typical lens flaws).
Longitudinal Chromatic Aberration
The Longitudinal Chromatic Aberration (also called Trasversal) shows up as reddish haloes around edges of objects closer than the focus plane and greenish haloes around edges of objects further than the focus plane.
Both the Batis and the Tamron show very good performances for this aspect, with clean out-of-focus edges, controlling this aberration very well.
For example the famous Sony Zeiss 55mm f1.8, reknowned for high sharpness, suffers from visible longitudinal chromatic aberration:
Lateral Chromatic Aberration
The Lateral Chromatic Aberration is the flaw, very very common in lenses, for which contrasty edges on in-focus objects show purple haloes. Again both models control very well this problem, especially after in-camera auto-correction, but being nitpicky the Batis here is better: if you look the shots at 100%, then the Batis shows up cleaner in contrasty edges:
In those images you see details enlarged 3 times so for whom using these lenses with a A7 III camera (24 megapixels) there's really nothing to worry about. For higher resolution, like A7RIII/IV with 42 or more pixels, the Batis is a bit cleaner but just in the very fine details.
When shooting at light points like city lights at night or stars, one of the typical lens flaws in the borders/corners is that points become like little comets, then some other imperfections can influence the shape of the light points like astigmatism and stars in the corners of the frame can become little triangles.
Regarding this typical optical defect, the Tamron and the Batis behave well, though pixel-peeping at 100% the Batis is a bit cleaner since it has even lower aberrations. Let's see first the better performance of the Batis on an edge of the frame:
and then in a corner (notice the street lamp in the center):
Instead, light points are absolutely clean without coma in the central area of the frame.
Optical quality summary: both lenses very good, overall on a par regarding very high sharpness, a bit better the Batis in the micro-detail for even less aberrations, but the Tamron allows close-up shots.
For a (super)wide angle lens, smooth out of focus is not its main usage and goal, but its wider aperture at f2.8 allows good subject separation with close subjects.
In both models the colored circles that are produced when shooting out-of-focus lights show the typical onion structure (concentric circles) and not a single, smooth circle, quite common in lenses (especially with a lot of special/aspherical elements).
In the Batis the outline is a bit softer than in the Tamron that presents sometime a double outline:
Summary: both lenses are not aimed at best bokeh shots, slightly softer/better the Batis.
Both models, thanks to their anti-reflection coatings, are very resistant to flare in back-light, contrast remains good and very rare reflex artifacts, in general great performances.
Even with the sun inside the frame in the corner, the Tamron is perfect, the Batis does not loose contrast but sometimes it can show some artifact, not bothering.
Summary: both with very good performances, the Tamron even better.
Conclusions and Evalutations
Now that we have compared many aspects of the two models, we can conclude that both ones are a great choice for a high quality wide lens in the 16-20 mm focal range. Let's summarize the comparison in a table.
|Build||on a par||on a par, 90 gr lighter|
|Focal range|| |
more flexible (17-28 mm)
max magnification 0.19x
only 18 mm
>max magnification 0.11x
great at 17mm, soft corners for close subjects
less sharpness towards 28mm
|great at 17mm, corners a bit softer but good stopping down|
|Aberrations||well controlled||very well controlled|
|Flare||very well controlled||well controlled|
|Price||1000 €||1300 €|
Summing up, I might suggest to pick up:
- the Tamron for focal range, starting also 1 mm wider and with more close up possibilities, along with overall great quality. My preferred choice.
- the Batis to obtain even higher quality in the details regarding control of aberrations and less distorsion, but accepting the restriction of a single focal length.
In the 16-20 mm focal range with a relatively fast aperture (f2.8 or wider), there are currently at least other 7 models (not considering the Mitakon 20mm f/2 4.5x Super Macro that is essentially only for macro):
- Sony 16-35 f2.8 GM: great build and optical quality, 680 gr weight and above all.. much more expensive (more than 2500 €).
- Samyang AF 18mm f2.8: lower flare resistance than the Tamron/Batis and not weather sealed, but much cheaper (around 350 €), extremely light and not less sharp than the Tamron.
- Sigma 14-24 f2.8 DG DN Art: new model announced in July 2019, it promises the super-sharpness of Art series and the focal range is very interesting, more expensive (around 1600 €) and heavier.
- Tokina Firin 20mm f2 in their versions MF and AF: very good lens, also for astrophotography having very low coma, the AF version costs a little less than the Tamron. It's also 1 stop faster at f/2 vs f2.8 of Tamron/Batis. Autofocus is noisy and a bit slow, so not good for video.
- Sigma 20mm f1.4 DG HSM Art: very good quality and even 2 stop faster at f/1.4, at a price comparable with the Tamron. Downside: much heavier at 950 grams.
- Viltrox PFU RBMH 20mm F1.8 ASPH: a relatively new Chinese producer that is making good quality lenses, Tamron/Batis are optically better at a double price than the Viltrox.
The Tamron appears to be a very good all-around quite fast and light wide angles zoom solution.
Interested in buying the Tamron 17-28 or the Batis 18 in US? Here you have the US Amazon offers (LightPoint is an Amazon affiliate - thanks if you use these link to support our site!)
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