Panasonic Leica DG Summilux 25mm f1.4 ASPH. (H-X025) Lens
A fast prime lens that covers a ‘normal’ field of view and supports the advanced autofocusing systems in the latest Panasonic G-series cameras.The Leica DG Summilux 25mm f/1.4 ASPH. lens was announced by Panasonic in June 2011 at the same time as the Lumix DMC-GF3 camera. It’s due for release locally at the end of August. On G-series bodies, it provides an effective focal length equivalent to 50mm on a 35mm camera, making it an excellent ‘standard’ lens. . . [more]
The Leica DG Summilux 25mm f/1.4 ASPH. lens was announced by Panasonic in June 2011 at the same time as the Lumix DMC-GF3 camera. It’s due for release locally at the end of August. On G-series bodies, it provides an effective focal length equivalent to 50mm on a 35mm camera, making it an excellent ‘standard’ lens.
The Leica DG Summilux 25mm f/1.4 ASPH. lens. (Source: Panasonic.)
Roughly twice the length and double the weight of Panasonic’s popular 20mm f/1.7 ‘pancake’ lens, which we reviewed in September, 2009. It has been designed to replace the pancake lens as the premium prime 25mm lens for still photography enthusiasts.
The 25mm focal length of this lens is equivalent to 50mm on a 35mm camera, which imparts a normal perspective, similar to that of standard human vision. Its optical design is more complex than the 20mm lens and consists of nine elements in seven groups with two glass-moulded aspherical elements to counteract distortion and chromatic aberrations. One UHR (Ultra High Refractive) index lens is included to optimise flatness of field, enabling this lens to be used for copying.
The optical design of the Leica DG Summilux 25mm f/1.4 ASPH. lens showing the positions of the exotic elements. (Source: Panasonic.)
Panasonic’s Nano Surface Coating technology, which applies nano-particles as surface coatings, dramatically reduces reflections across the visible spectrum (380nm-780nm), significantly reducing flare and ghosting. This enables the lens to produce images with optimal clarity and sharpness in a wide variety of lighting conditions. Seven diaphragm blades close to a rounded aperture for attractive bokeh at wide aperture settings. The fast f/1.4 maximum aperture is advantageous for depth-of-field control as well as in low light levels, although you need a camera with depth-of-field preview to fully appreciate its effect.
Build and Handling
Evidence of above-average build quality can be seen in the metal lens mount, which ensures long-term performance reliability. In addition, the lens barrel appears to combine aluminium alloy and polycarbonate, although Panasonic has provided no information on its construction.
The 20 mm wide focusing ring lies approximately 15 mm behind the front of the lens barrel. This ring moves very smoothly and positively, making accurate manual focusing straightforward. In front of it the barrel is threaded to accept 46 mm filters (the same size as used by the 20mm pancake lens).
Unfortunately, a few desirable features are missing. There’s no aperture ring and neither distance nor depth-of-field scales and the lens lacks built-in image stabilisation. The only other feature is the red dot that is matched to a similar mark on the camera body when the lens is attached.
Autofocusing is driven by a micromotor, which is relatively old technology and neither as fast nor as quiet as ultrasonic AF drives, although the DG Summilux 25mm f/1.4 is slightly quicker and quieter than the 20mm lens. It also supports the G3’s contrast AF system and Continuous AF mode, while the 20mm lens doesn’t. Face Recognition AF is also fully supported.
Full time manual focusing is available in AF mode. However, manual focusing is ‘fly-by-wire’, which means there’s no direct link between the focusing ring and the lens focusing mechanics. Without the focusing motor engaged, the ring turns freely when the camera’s power is switched off.
Close focusing is restricted to 30 cm, which isn’t quite close enough for photographers who like taking close-ups of small flowers and insects. (The pancake lens can focus down to 20 cm, which is also fairly limited.)
Compared with the 14-42mm kit lens, which has a maximum aperture of f/4.6 at 25mm, the DG Summilux 25mm f/1.4 is noticeably brighter and, therefore easier to focus manually, should you require manual focusing. Its shallower depth of field at maximum aperture enables users to isolate subjects far more effectively and it provides much more attractive bokeh, as shown in the illustration below.
The left hand image was taken with the DG Summilux 25mm f/1.4, while the image on the right was taken with the 14-42mm kit lens. Both lenses were set on their maximum apertures.
Supplied accessories include front and end caps plus a rectangular hood and a soft carrying pouch. The hood was easy to fit and attached securely to the lens. Unfortunately it can’t be reversed over the lens for transportation.
Our tests on this lens were carried out on the G3 body. The wide maximum aperture provided excellent control over depth-of-field and the touch focus system made it possible to focus precisely on specific areas of subjects and was particularly valuable when shooting close-ups.
Imatest showed the review lens to be capable of high resolution through its aperture range, with the highest performance being between f/2.2 and f/6.3. The graph below shows the results of our tests on JPEG files.
Edge sharpness was generally excellent and lateral chromatic aberration was negligible across all aperture settings, as shown in the graph below. The red line at the right hand edge of the graph marks the border between ‘negligible’ and ‘low’ CA.
Slight vignetting was detected at f/1.4 but this was gone by f/2.2 and vignetting was negligible at smaller apertures. Rectilinear distortion was also negligible. The wide aperture also provided a bright enough image to support manual focusing after dark.
In backlit conditions, flare and ghosting were relatively low, although it was possible to force the lens to flare when the light source was just outside the frame. Despite the limits to the close focusing range, bokeh at wide aperture settings was smooth and attractive.
Buy this lens if:
– You want a fast lens for available light photography and require high performance across a wide aperture range.
– You require distortion-free images.
– You have a camera body that can capitalise on its features.
Don’t buy this lens if:
– You really need a zoom lens.
– You shoot lots of close-ups.
RW2.RAW files converted with the Silkypix Developer Studio software supplied with the G3, on which this lens was tested.
Vignetting at f/1.4.
Vignetting at f/2.2.
Distortion is effectively negligible; ISO 160, 1/1000 second at f/1.6.
Close-up at f/2.2; ISO 160, 1/1600 second.
ISO 160, 1/4000 second at f/1.4.
ISO 160, 1/800 second at f/8.
ISO 160, 1/200 second at f/16.
Flare; ISO 160, 1/800 second at f/9.
Backlighting; ISO 160, 1/500 second at f/7.1.
In the following series of images, the red circle on the right hand dog’s nose indicates the touch focus point used for the shot. (The camera was tripod-mounted for the series.)
ISO 200, 1/320 second at f/1.4.
ISO 200, 1/40 second at f/4.
ISO 200, 1/5 second at f/11.
ISO 200, 1/2 second at f/16.
Picture angle: 47 degrees
Minimum aperture: f/16
Lens construction: 9 elements in 7 groups (2 aspherical lenses, UHR (Ultra Refractive Index) lens)
Lens mounts: Micro Four Thirds mount
Diaphragm Blades: 7 diaphragm blades / Circular aperture diaphragm
Focus drive: Micromotor
Minimum focus: 30 cm
Maximum magnification: Approx. 0.11x / 0.22x (35 mm camera equivalent)
Filter size: 46 mm
Dimensions (Diameter x L): 63 x 54.4 mm
Weight: Approx. 200 grams
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