Testing: Longitudinal Chromatic Aberration and focus shift
Lenses with focal ratios of f2.8 or larger are often prone to longitudinal color aberrations (loCA, a.k.a. “axial color” or “Bokeh CA”). These normally show up as magenta coloration in the foreground and greenish hues in the background and are not easily corrected in post-processing. The Sony FE 35mm f1.8 shows some loCA. The following 100% crops show the foreground on the left and the background on the right with the first crop at f1.8, second at f2.0, third at f2.8:
The test also revealed that there is no focus shift. For comparison have a look at the Sony FE 35mm f1.4 ZA which has pretty prominent loCA , Sony FE 35mm f2.8 ZA at f2.8 and f4.0, Sigma 35mm f1.4 Art, Sigma 35mm f1.2 DG DN Art, Samyang AF 35mm f1.4 EF. All f1.4 lenses are shown at f1.4/f2.0/f2.8, the f1.2 Sigma Art at f1.2/f1.4/f2.0/f4.0.
The following real life shot shows that the Sony FE 35mm f1.8 produces some purple fringing around high-contrast edges in the focal plane and green outlining around background subjects:
Sharpness and contrast
Let’s have a look at the theoretical performance of the Sony FE 35mm f1.8 first and compare it to some alternatives:
The MTF charts of the Zeiss (designed) ZA lenses from Sony show the contrast wide open at 10 (red), 20 (green) and 40 line-pairs per mm (purple). The computed MTF chart of the other lenses from Sony, Samyang and Sigma shows contrast at 10 lp/mm (red) and 30 lp/mm (green) wide open without influence of diffraction. Higher values are better (more contrast) and the closer the solid and dotted lines are together the less astigmatism (= resolution depends on the orientation of the test-pattern) the lens has. The x-axis displays the distance from the optical axis (=center of the sensor) in mm. I’ll show you the real-life performance at 4 mm (center), 13 mm (APS-C-corner), and 20 mm (FF-corner) on a 42MP Sony A7R II body for the Sony lenses.
From the charts almost every lens shows a clear dip in sharpness around 12-15mm off-center, only the new Sigma 35mm f1.2 DG DN Art has a very gradual slope in sharpness towards the full-frame corner at an astonishing level for its f1.2 focal ratio. And both the Sony 35mm f2.8 ZA and the Sigma 35mm f1.4 Art suffer steep drops in resolution at the FF-corner. But other than that the different methodologies and different focal ratios used in these charts makes it hard to compare these lenses. So let’s see how they perform in my sharpness test based on Siemens-stars. Processing was done in Lightroom 8/CRAW 11 from RAW to Adobe Color profile using the built-in lens profile where applicable. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. White-balance was adjusted to a neutral white and I did some exposure compensation to make the brightness of all crops match. So you will not see light fall-off in the corners.
The following 100% crops show the Sony FE 35mm f1.8 at f1.8 compared to the Sony FE 35mm f1.4 ZA, Samyang AF 35mm f1.4 FE, and Sigma 35mm f1.2 DG DN Art at f1.7.
In this comparison at f1.7/f1.8 the Sony FE 35mm f1.8 is clearly sharper across the sensor than the Sony FE 35mm f1.4 ZA. It’s also sharper than the Samyang in the center but is softer in the FF-corner. Vis-a-vis the new Sigma 35mm f1.2 DG DN Art the Sony FE 35mm f1.8 is of comparable sharpness within the APS-C image-circle but again a bit softer in the FF-corner.
Now let’s see how the Sony FE 35mm f1.8 compares to the Sigma 35mm f1.4 Art at f2.0. The Sigma was shot on a 36MP Nikon D800 and processed the same except for a little higher sharpening – which both should work a bit in favor of the Sigma:
In this comparison at f2.0 the Sony FE 35mm f1.8 beats the Sigma 35mm f1.4 Art with a much better APS-C-corner.
Following is the comparison with the Sony FE 35mm f2.8 ZA at f2.8:
At f2.8 both lenses are equally sharp in the center but the little Sony FE 35mm f2.8 ZA clearly falls behind the new Sony FE 35mm f1.8 toward the FF-corner.
Let’s see how the Sony FE 35mm f1.8 develops when stopped down further:
Stopping the Sony FE 35mm f1.8 further down does not gain much over the performance at f2.8: the FF-corner gains a little contrast at f4.0 but does not sharpen up any further.
Performance at long distances
The Siemens-star test-targets are shot at a distance of 45x focal length (i.e. at around 1.6m). But as performance of lenses also depends on the shooting distance I did another series of test-shots of a city around 1 km away. Processing was done in Lightroom 8/CRAW 11 from RAW to Adobe Color profile with the lens-profile automatically applied. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. I used autofocus at the largest aperture and did not change focus for other apertures.
The main image shows the complete scene wide open to give you an impression of the angle of view and to judge vignetting. You can access the respective shots up to f11 via the links beneath the main image. Following the main image are 100% crops from the Sony FE 35mm f1.8 at f1.8 compared to the Sony FE 35mm f1.4 ZA, Samyang AF 35mm f1.4 FE, and Sigma 35mm f1.2 DG DN Art at f1.7. All lenses were shot on the same day only minutes apart except for the Sony FE 35mm f1.4 ZA.
You can click on each image to access the large original. Please respect our copyright and only use those images for personal use.
The new Sigma 35mm f1.2 DG DN Art takes the top spot in this comparison: it’s simply very sharp and contrasty across the full-frame sensor. The Sony FE 35mm f1.8 is very close in the center and the FF-corner but suffers from some field-curvature at the APS-C-corner: The tree in the foreground is sharper than the background. Interestingly the Sony FE 35mm f1.4 ZA and the Samyang suffer from the same problem which makes the APS-C-corners of all three lenses look a bit soft. In the FF-corner the Sony FE 35mm f1.8 takes second place while both the Sony FE 35mm f1.4 ZA and the Samyang come last: Their FF-corner is not bad but softer than from the other two lenses.
Let’s see how the Sony FE 35mm f1.8 develops when stopped down further and compare it to the Sony FE 35mm f2.8 ZA at f2.8 (shot another day):
At f2.8 the Sony FE 35mm f1.8 has sharpened up quite nicely. The Sony FE 35mm f2.8 ZA trails behind the other lenses in this comparison with a generally softer rendering.
The new lens is very good at f2.8 already. So there’s only a very small gain in acuity at the APS-C-corner when stopping down to f5.6, eliminating the negative effects of field-curvature there. But that’s really only visible when pixel-peeping at 100%.
Rendering of point-light sources at night-shots
Night-shots pose a different challenge for lenses as the contrast is even higher than under bright sun and point-light sources can reveal some weaknesses such as coma, haloing and color-aberrations that do not show up as prominently in other test-shots. The 100% crops below the main image show the effect of coma in the FF-corner of the Sony FE 35mm f1.8 and the other lenses at various apertures:
The Sony FE 35mm f1.8 shows quite some coma deforming point-light sources into birdlike apparitions at f1.8 and f2.0. At f2.8 the effects is effectively minimized. The Sony FE 35mm f1.4 ZA is much better but still shows some coma at f1.4. The Samyang AF 35mm f1.4 FE and Sigma 35mm f1.2 DG DN Art produces practically no coma even wide open while the Sony FE 35mm f2.8 ranks last – although it has the slowest focal ratio.
Rendering of out-of-focus point-light sources
This test is for the rendering of point-light sources in an out-of-focus background. The circle of confusion that is produced by this test is pretty indicative of Bokeh performance (in the background) and light fall-off. Ideally the out-of-focus image of the point-light is evenly lit and perfectly circular, with no “onion-rings”, and without coloration. Large aperture lenses normally produce an effect known as “cat’s eye” the further away from the optical axis the point-light is projected. This is due to optical vignetting in the lens barrel when light enters the lens from an angle.
The larger the aperture, the larger the Bokeh balls in the center. Thus the f1.2 Sigma Art leads and the f2.8 Sony ZA is last – not only regarding the size of the Bokeh balls in the center but in this case also in the corners. The Sony FE 35mm f1.8 and the Sigma 35mm f1.2 DG DN Art have the smoothest texture inside with almost no onion rings while both Sony ZA lenses and the Samyang produce visible onion rings. Outlining is strongest with the Samyang and a little milder on the f1.8 and f2.8 Sony lenses. But all show a slight green coloration from loCA.
Let’s see how this analysis of out-of-focus point-light sources translates into Bokeh-performance shooting a book-shelf.
From the comparison above it is clear that the larger focal ratio (potentially) produces the better Bokeh: The Sigma Art leads in this comparison followed closely by the Sony FE 35mm f1.4 ZA. The new Sony FE 35mm f1.8 clearly suffers from its f1.8 focal ration and the Sony FE 35mm f2.8 ZA simply cannot compete with the other lenses in this comparison. But the Samyang shows that focal ratio is not everything when it comes to the quality of Bokeh: although shot at the same f1.4 aperture it exhibits a more nervous background and a less soft transition in the middle-ground then the Sony FE 35mm f1.4 ZA.
35mm focal length may not be the classical choice for portraits on a full-frame camera but the Sony FE 35mm f1.8 can well be used for upper body or full body shots when you get close enough. And it offers an angle of view equivalent to an 53mm lens on a cropped APS-C sensor. And the background blur at closer shooting distances is nice enough to give it a try. All shots were done from the same position/distance so perspective does not change between shots. There is slightly different framing from different effective focal length at the shooting distances and there are also some slight focus-differences which inevitably occur when you shoot a living, breathing subject. All images were developed from RAW to Adobe Color profile with identical white balance.
The Sony FE 35mm f1.8 goes down to 1:3.9 magnification which is better than the other lenses compared in this review. And its performance is very usable once you stop down to f4.0 or beyond. The following image was shot at 1:4.5 magnification where the area of sharp focus is just 108 x 162mm. The crops shown below are (from left to right) from 1mm, 10mm, and 18mm off the center of the sensor respectively:
Flare, ghosting, and sun-stars
Catching a strong light-source shining directly into the lens is always a risky business: it could produce strange colorful ghost-images or reduce contrast considerably through flare and glare. The appearance of flare and ghosting depends on factors like the aperture and the angle of the light hitting the lens. So to judge the proclivity of the Sony FE 35mm f1.8 for these artifacts I went through a series of well calculated shots against a strong light source to provoke glare and ghosting. The lens hood was mounted in all shots. Following are two of the more extreme example results. The little bright square inset in the upper left shows the respective area with an exposure compensation of +3 EV to make it easier to see which levels of black the lens renders at that point:
Flare and ghosting is very well controlled as is glare. And the sunstar in the top image looks very well defined. The flare from the upper right in the second image only occurs at a very narrow angle when the light-source is just outside the corner. For comparison have a look at the Sony FE 35mm f1.4 ZA here and here.
All-in-all the Sony FE 35mm f1.8 let’s you shoot confidently under adverse contra-light situations as long as you avoid strong light-sources just outside the corners.
Next check out my sample images!Check prices on the Sony FE 35mm f1.8 at B&H, Amazon, Adorama or WEX. Alternatively get yourself a copy of my In Camera book or treat me to a coffee! Thanks!