It is interesting how things changed during the last few years. There was a time when it (progress in photographic technology) all happened on the DSLR side but lately mirrorless systems are the leaders in innovation. Sony is certainly an aggressive player here and it doesn’t come as a surprise that they were the first to release a full-format mirrorless system. They are still in the ramp-up phase so the system doesn’t really offer many options. In its lens universe, there are less than a handful of available native lenses as of the time of this review. For our first test, we picked the Carl Zeiss Sonnar T* FE 35mm f/28 ZA for a ride on the A7R. Over time we’ll also review all the others, of course – the FE 24-70mm f/4 OSS is already sitting on my desk …
Some may wonder about the meaning of “Sonnar” in the name. Sonnar is derived from the German word “Sonne” (sun) and is used for fast lenses. That being said – just from its specs it isn’t an overly exciting lens – it is a moderate wide-angle with a relatively uninspiring max. aperture for a prime lens. The suggested retail price of 800US$/EUR may come as a shocker but Zeiss lenses were never budget items to start with.
The Sonnar is a tiny being with a marginal weight. Some may miss the feeling of “substance,” but the build quality is actually excellent … it would have been difficult to mess up such a comparatively simple lens anyway. The outer barrel, the mount as well as the focus ring are made of metal whereas the inner frame for the optics is made of plastics. Everything is tightly assembled with no wobbling. The focus ring operates smoothly and it’s even slightly dampened. The lens also features a weather sealing. The supplied (plastic) lens hood is pretty interesting. It isn’t overly deep but functions like a mask where the borders of the hood have an inward-facing design (see below).
The Sony A7R is not a speed machine regarding its AF performance so it’s hard to judge the qualities of the lens in this respect. When ignoring the AF hunting caused by the camera, the focus changes seem to be quite quick – there aren’t many moving parts anyway and the internal focusing mechanism also helps. AF operations are also essentially noiseless. Typical for E-mount lenses, focusing works “by-wire”. The implementation is really good and allows very fine-grained focusing.
| Specifications | |
|---|---|
| Optical construction | 7 elements in 5 groups inc. 3x aspherical elements |
| Number of aperture blades | 7 (circular) |
| min. focus distance | 0.35m (1:8.3) |
| Dimensions | 61.5×36.5mm |
| Weight | 120g |
| Filter size | 49mm |
| Hood | supplied, compact-style, bayonet mount |
| Other features | Weather Sealing |
Distortion
The Zeiss lens shows a slightly mustache-style distortion type which our tool interpreted as “pincushion”. In any case it is marginal and very low for a wide-angle lens.
Vignetting
The auto-corrected light falloff at max. aperture is very moderate for a lens on a full format camera. At f/2.8, we are seeing a light falloff of 1.3EV (f-stops). Stopping down doesn’t help a lot with a best low value of just under 1EV. This remains visible in certain scenes.
The situation changes when looking at the uncorrected data. At fully open aperture, the falloff is a hefty 2.6EV. Stopping down to f/8 gives you 1.6EV which is still not good. Please note that the auto-correction effect is clearly visible in the image corners – due to the signal amplification they are more noisy than the image center. It is interesting to note that the RAW files are also touched when activating the auto-correction in the camera.
MTF (resolution at 36 megapixels)
Generally the Zeiss Sonnar delivers the high resolution figures that we expect from a lens with the blue (Zeiss) label. The center performance is already tack sharp at max. aperture. The borders are very good here whereas the corners are slight softer. The corners improve substantially the more you stop down with a good to very good peak at f/5.6. Diffraction has a higher impact from f/11 onward but this setting remains easily usable.
The centering quality of the tested sample was good.
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)
The Zeiss lens produces a quite low amount of lateral CA (color shadows at harsh contrast transitions) of under 1px at the image borders. This is impressive on such a high-resolution sensor.
Bokeh
The Zeiss Sonnar T* FE 35mm f/2.8 ZA delivers pretty good but not outstanding results regarding bokeh quality (out-of-focus rendition). Out-of-focus highlights have a circular shape at f/2.8 but the inner zone slightly nervous. This gets even more apparent the more you stop down. It is also somewhat disappointing that the aperture has an edgy shape at f/4 already.
On the positive side, the rendition in the critical focus transition zone is very smooth and buttery both in the fore- and background. This is a rare quality.
Bokeh Fringing / Longitudinal Chromatic Aberrations (LoCA)
Bokeh fringing is a common characteristic with fast glass. It’s visible as halos of different colors in out-of-focus areas – magenta (red + blue) in front of the focus point and green beyond.
The Zeiss lens exhibits a significant amount at f/2.8 and it’s even slightly visible at f/5.6. This is a bit surprising since the effect tends to be gone beyond f/4.
Sample Images
The Zeiss Sonnar T* FE 35mm f/2.8 ZA is undoubtedly a very good performer but it's not flawless. The image center is certainly of stunning quality but the borders and more so the corners can't quite follow. Very sharp images across the image field are still possible at medium apertures. Distortions are generally not an issue. There is a certain degree of light falloff but while this may be visible at times it is not dramatic either … when choosing the lossy auto-correction option. The uncorrected vignetting is significantly higher. The quality of the bokeh is generally very good except for the rendition of out-of-focus highlights. Bokeh fringing can be an issue in critical scenes, especially for close focus.
On the mechanical side there isn't really anything to complain about thanks to a tightly assembled metal construction with weather sealing. We also like the really cool, compact lens hood. The AF has the potential to be fast but it is held back by the rather slowish Sony A7R. Manual focusing is very precise and smooth - something that you may not associate with a focus-by-wire system.
Thus the Zeiss lens is, of course, an interesting option. However, the pricing seems to be a bit over the top. Time will tell whether Sony has at least invested some of the associated revenues into better quality control - this wasn't really their strength in the past in our book … to say it politely.
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Optical Quality
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Build Quality
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Price / Performance