Image Quality
So the big question: did Zeiss succeed in packing outstanding optical quality into a small package? The answer is an unqualified YES. As you’ll see in the images and in my description, the Loxia 21mm is a phenomenal optic.
Sharpness
For landscape shooters, having an ultra-wide that provides excellent edge to edge sharpness is of great concern, and the Loxia 21mm delivers in spades. The lens is very sharp across almost the entire frame right from f/2.8. Just a hint of edge and corner softness shows at this aperture. Stop down a bit and the Loxia 21 sharpens up to produce truly excellent sharpness from extreme corner to extreme corner. It’s remarkable to see that level of performance in a lens this wide. When I reviewed the excellent Fuji 14mm f/2.8 (which has the same angle of view as this lens, as it’s an APS-C lens), I remarked that it was the finest wide-angle lens I’d ever used. I directly compared the two, and one thing was immediately clear: the Loxia is sharper. Notably so at wide apertures, but it even outresolves it in the corners stopped down.
Bokeh
You wouldn’t think that bokeh would be a major concern with an ultra-wide lens, but for close-up work, the Loxia 21mm can definitely create plenty of blur. The bokeh of the 21mm f/2.8 is actually fairly good. Specular highlights are neutral and while the bokeh is high in contrast, it falls short of nervous, creating a predominantly pleasing rendition of out of focus areas.

Color, Contrast and Chromatic Aberration
While the sharpness was outstanding, the area where the legendary C/Y 21mm Distagon most excelled was in the exceptional contrast and color that the lens could produce. I’m happy to report that the Loxia 21mm fits that same mold. The Loxia 21mm has exceptional micro-contrast, astounding macro contrast and amazingly rich color. The first shot posted on this page shows all three in their glory. This shot had a minimum of post-processing, with some minor curves adjustment and virtually zero saturation adjustments. If you enlarge that image, you’ll note the astounding micro-contrast in the snow on the left side, while the buildings simply pop. On a few of the other night images in the Image Samples, I actually had to lower saturation, as the default RAW setting looked almost fake. While this won’t be the case with most scenes, you can expect a contrasty, saturated look out of the Loxia 21mm. In my opinion, the images almost leap out at you.
The Loxia 21mm can show some very slight lateral chromatic aberration if you look for it, but overall performance in this regard is excellent for a wide-angle. Longitudinal CA is also not a problem.
Distortion, Flare and Vignetting
The Loxia 21mm performs fairly well with regards to distortion. The native optical properties of the lens show some barrel distortion with a mustache character (barrel in the center, pincushion at the edges), but the lens also has a distortion profile for JPEGs as well as application in most RAW converters. The distortion correction works extremely well, and impact to sharpness is exceptionally minimal. If it helped increase the performance in other areas, I’m more than happy with the tradeoff of some digital distortion correction.
The Loxia 21mm also shows some vignetting at wide apertures that can also be corrected with a profile, though stopped down this mostly disappears. Overall, not much to worry about here.
With flare, the lens itself performs admirably. There is no loss of contrast with bright lights in the frame, including mid-day sun in a clear blue sky. It also produces almost no ghosting whatsoever. However, there is something about the construction of the lens that does cause reflections off the image sensor to be visible in the final images, at least on the A7 II. Going back through all my other images, I was able to spy subtle hints of reflections with a few other lenses, but nothing like the blatant ones present with the Loxia. The original A7 had a fairly major issue with sensor reflections, and the Mark II tempered that quite a bit. However the Loxia brings out the worst in the A7 II with regards to sensor reflection, so if using it on that body (or the original A7 or A7R), you’ll really want to watch it if the sun is prominent in the frame. From talking with other photographers, the issue is minimal to non-existent on the A7R II. See the shot below for a typical presentation of these sensor reflections
In all, the optical performance of the lens is simply phenomenal.
Jordan,
Excellent review as usual! This for sure is an extremely desirable lens but I concur with you on the practicality of using the Sony/Zeiss FE 16-35mm. The one-stop gain and marginally better performance with the Loxia, is not for me enough to overcome the convenience of carrying a single zoom.
On the other hand, I really look forward to hear from you on the forthcoming Voigtlander 10mm and 12mm in E-mount. Both are appreciably outside the 16-35mm range to make them potentially very interesting. And I love those extreme wide-angle perspectives!
Thanks again!
Marc
Interesting observation about the sensor reflection. I was wondering if sensor reflection is also visible in the image “Sunlight – Sony A7 II with Sony FE 28mm f/2 @ f/16” on the third page of your review of the Sony FE 28mm, or is that just regular flare?
That’s illumination of the dirt on the window I was shooting through.
Good review! Did you had a chance to use the Loxia with a filter system? I’m interested whether it works with the Lee 75 system.
Is this lens designed specifically for the Sony? (I’m assuming so) that is some serious quality. When you reviewed this the 16mm Fuji wasn’t made yet. Is it the same type of lens? Is there anyway of adapting this bad boy to an XPro2 and retaining that quality. Which Sony is this made for? All E mount? Thanks for the review and these great images. Looks like 4×5 almost.
Thanks for the informative review, Jordan!.
What do you think: Could the field curvature of the lens be due to the distortion correction?
You’ say the “thick sensor cover glass” in the Sony cameras make adequate lens constructions like a Loxia necessary. I remember Cicala from LensRentals demonstrating, that third party lenses deliver optical performance according to the thickness of the sensor cover glass in the particular camera. That’s why I’m wondering whether the sensor cover glass in the A 6000 / A 6300 is as thick as that in the A 7 series? And do you know what third party lens makers offer lenses that in the said sense are suited to the Sony cameras?
Thank you again!
Hello Jordan, although English is not my native language, I am always carefully checking your comments and conclusions. Really great insights!
One thing that hit me when checking the ultra wide angle / wide angle reviews you and others specialists are running is that I do not see any good test of the Sony FE 20 mm f:1,8 G (or anything as good as what you are doing). Any plan to review this lens?
Thank you.