Leica APO-Summicron SL 35mm f/2 ASPH lens

      Photo Review 8.9

      In summary

      The APO-Summicron-SL 35 f/2 has a professional-level build quality and delivered excellent performance in our tests. It’s nicely matched in both form and performance to the SL2-S camera we used for our tests.

      The lens is well suited to reportage and photojournalism as well as being usable for other genres like architecture, landscapes, portraiture and studio work.

      Full review

      Leica’s APO-Summicron-SL 35 f/2 ASPH. is arguably the largest 35mm prime lens we’ve ever tested and one of the most expensive. It’s certainly not the fastest in its class; Sigma’s 35mm f/1.2 DG DN Art lens, which is a third of the Leica’s price, takes that prize. But the Leica wins out for build quality and overall performance and it’s nicely matched in both form and performance to the SL2-S camera we used for our tests.

      Side view of the APO-Summicron SL 35mm f/2 ASPH lens. (Source: Leica Camera.)


      The ‘APO’ tag means this lens is one of Leica’s most highly-corrected lenses. Accordingly, its optical design consists of 13 elements, which are arranged in 11 groups. Nine of the elements are made from anomalous partial dispersion (low-dispersion) glass to control fringing, while three are aspherical (two of them dual-surface aspherical) for reducing spherical aberrations to optimise sharpness.

      This diagram shows the positions of the aspherical elements and focusing elements in the APO-Summicron-SL 35 f/2 ASPH. Lens. (Source: Leica Camera.)

      Multi-layer coatings have been applied to suppress stray light that can create flare and ghosting so image contrast are retained when the lens is used in backlit conditions. An AquaDura coating has been applied to the surfaces of the front and rear elements to repel water and grease.

      This illustration shows the positions of the two stepping motors that drive autofocusing. (Source: Leica Camera.)

      The AF system is based on two lightweight focusing lenses and uses a Dual Syncro Drive stepping motor with two actuators to independently control the  two focusing elements. Leica claims the AF motors can span the full range in approximately 250 milliseconds.

      It’s not quite as fast as phase detection AF because Leica and Panasonic cameras rely on contrast AF with depth detection, which require several contrast measurements at various positions to be made to determine the way and how far to move the focusing elements.  But it’s quiet enough to use while recording video clips and very precise when it lock on.

      Manual focusing is achieved by turning a ring that uses a magnetic field sensor to provide fast and precise adjustments and is not affected by temperature fluctuations. The lens also boasts extensive weather-resistant sealing, with special seals around the focus ring to keep out dust and moisture. It is supplied with the usual front and rear caps, a lightweight metal lens hood with a rectangular front and a soft lens bag.

      Who’s it For?
      The 35mm focal length provides very modest wide-angle coverage that is often preferred by photographers over the ‘standard’ 50mm field of view. It is well suited to reportage and photojournalism as well as being usable for other genres like architecture, landscapes, portraiture and studio work.

      The L-mount means this lens can only be used on ‘full frame’ cameras from Leica, Panasonic and Sigma’s fp / fp L models. However can also be used with L-mount APS-C cameras like the Leica CL and TL2, where it provides a 52.5mm equivalent focal length.

      The high price of this lens is likely to be a major deterrent, although owners of Leica cameras should have the wherewithal to make the investment. Performance on the Panasonic S series cameras should be comparable with the performance on the Leica SL2-S camera we used for this review.

      Build and Ergonomics
      You’d expect a Leica lens to be well built but the APO-Summicron-SL 35 f/2 is built like a tank – and large and heavy to boot. Weighing 750 grams and 102 mm long, it’s obviously made almost entirely from metal and glass.

      This illustrations shows the APO-Summicron SL 35mm f/2 ASPH lens fitted to a camera. (Source: Leica Camera.)

      The focusing ring sits well back along the barrel, beginning 25mm from the front of the lens. The ring is 48 mm wide, with a 30 mm wide band of rubber ridging around its leading edge. Because focusing is driven from the camera, it turns through 360 degrees when power is off and it has no hard stops.

      Neither aperture ring nor distance scale is provided and there is no depth-of-field indicator. All these functions are driven from the camera’s menu system.

      The lens barrel continues for s further 30 mm before sloping inwards for 5 mm to end in the lens mount. Two ribbed ‘contact strips on this section of the barrel provide gripping surfaces for users when removing the lens from a camera (or fitting it).

      The barrel ends in a very solid mounting plate, which is surrounded by s thin rubber flange for excluding moisture and dust. Eleven gold-plated contacts inside the mount provide contact points for interfacing with electronic signals from the camera. A raised red dot on the outer barrel provides a reference point for fitting the lens to a camera.

      The lens is supplied with a metal lens hood (shown above) plus a soft carrying pouch.


      The review lens delivered excellent performance in our Imatest tests, meeting expectations for resolution in JPEGs in the centre of the frame and comfortably exceeding expectations in both centre and edge of the frame with DNG.RAW files. Imatest showed the lens to be sharpest at f/5 resolution remained high from f/2.5 through to f/8, where diffraction began to take effect. The graph below shows the results of our Imatest tests.

      Lateral chromatic aberration remained well down in the negligible band at all aperture settings and we found no evidence of coloured fringing in any test shots. In the graph of our test results below, the red line indicates the boundary between ‘negligible’ and ‘low’ CA.

      Backlit subjects were handled well, although we did encounter some situations that produced flare artefacts. However, ghosting was not encountered and contrast remained high at all times.

      The review lens showed very little vignetting and was almost distortion free, regardless of the file format.   Autofocusing was very fast, although not the fastest lens we’ve tested.

      The fault lies mainly in the camera’s detection system which is not as good as the hybrid systems in the latest cameras. Subject tracking was competent given the limitations of the camera and lens and we found no indication of camera sounds in any of the video clips we recorded.
      Bokeh was very smooth and attractive for a 35mm prime lens and we found no instances of outlined highlights, even at 16mm. Bokeh fringing, a common characteristic with faster lenses, was not detected.


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      Picture angle: 63.4 degrees
      Minimum aperture:  f/22
      Lens construction:13 elements in 11 groups (including  3 aspherical elements)
      Lens mount: Leica L bayonet
      Diaphragm Blades:   (circular aperture)
      Weather resistance: Yes
      Focus drive: Dual Syncro Drive stepping motor
      Stabilisation: No
      Minimum focus: 27 cm
      Maximum magnification: 0.2x
      Filter size: 67 mm
      Dimensions (Diameter x L): 73 x 102 mm
      Weight: 750 grams
      Standard Accessories: Front and rear caps, lens hood, lens bag
      Leica Camera Australia, (03) 9248 4444.



      Based on JPEG files recorded with the Leica SL2-S camera.

      Based on DNG.RAW files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.



      Vignetting at f/2.

      Rectilinear distortion.

      Close-up at f/2, 1/4000 second at ISO 100.

      Bokeh at f/2, 1/3200 second at ISO 100.

      f/10, 1/6 second at ISO 100.

      Crop from the centre of the above image at 100% magnification.

      Crop from the corner of the image at 100% magnification showing egde softening.

      Crop from the edge of the above image at 100% magnification showing traces of coloured fringing.

      Sunstar at f/22 in backlit scene, 1/4 second at ISO 100. Note the small flare artefact in the lower right corner.

      Contre-jour lighting; 1/640 second at f/9, ISO 100.

      1/50 second at f/11, ISO 100.

      1/50 second at f/16, ISO 100.

      1/400 second at f/8, ISO 100.

      Additional image samples and test results can be found with our review of the Leica SL2-S camera.



      RRP: AU$7300; US$5195

      • Build: 9.0
      • Handling: 9.0
      • Image quality: 9.0
      • Autofocusing: 8.8
      • Versatility: 8.8