Leica Summilux-M 21mm 1.4 ASPH User Manual
LEICA SUMMILUX-M 21 mm f/1.4 ASPH.
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The LEICA SUMMILUX-M 21mm f/1.4 ASPH extends Leica's series of high speed M lenses into the wide-angle range.
It offers excellent performance over the entire image field even at full stop and in the close-up range thanks to a "floating element". Stopping down to 2.8 leads to an absolutely outstanding image quality, in fact, in comparison to the Elmarit lens of the
same focal length, its rendition is slightly more uniform across the image field. The vignetting typical of every optical system is
naturally more apparent with a super wide angle lens, particularly a high speed one like this, than on standard lenses or those
with a long focal length. At full stop with the 35mm format, its maximum - i.e. in the corners of the image - is around 3.2 aperture
stops or, with the Leica M8 models and their slightly smaller format, around 1.9 aperture stops. Stopping down to 2.8 visibly
reduces this light fall-off towards the image edges to 1.7 or 0.8 aperture stops. Stopping down further does not bring any noticeable additional reduction, as all that remains is essentially the natural vignetting. The maximum distortion of the lens is 2.3%,
which in practical terms is negligible for the majority of photographic applications. A total of ten lens elements are used to achieve this exceptional performance. To correct color aberrations, five of these are made of glass types with anomalous color dispersion (partial dispersion), while a further two have aspherical surfaces. To maintain performance in the close-up range, one group
towards the rear of the optical system is a "floating element" that moves independently of the rest of the mechanism.
Summary: The LEICA SUMMILUX-M 21mm f/1.4 ASPH offers maximum image performance with a focal length / speed combination previously unavailable in the M system. This extends the composition options of M photography, particularly for available light
shots, but also thanks to a previously unattainable reduction in the depth of field in combination with large angles of view.
Lens shape
ASPH.
Floating element
LEICA SUMMILUX-M 21 mm f/1.4 ASPH.
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Engineering drawing
Technical Data
Angle of view (diagonal, horizontal, vertical)
Optical design
Distance setting
Aperture
Bayonet
Filter mount
Lens hood
Dimension and weight
92° / 81° / 59°
Number of lenses/groups: 10 / 8
Focal length: 21.6 mm
Position of entrance pupil: 24.4 mm (related to the first lens surface in light direction)
Focusing range: 0.7 m to infinity
Scales: Combined meter/feet graduation
Smallest object field: 685 x 1027 mm
Largest reproduction ratio: 1:29
Setting/Function: With click-stops, half values available, manual diaphragm
Lowest value: 16
Leica M quick-change bayonet with 6 bit lens identification bar code for digital M models
Series filter VIII in lens hood
Seperate, screw-on type
Length: 66 / 77 mm (without / with lens hood)
Largest diamater: approx. 69.5 mm
Weight: approx. 580 g
LEICA SUMMILUX-M 21 mm f/1.4 ASPH.
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MTF graphs
The MTF is indicated both at full aperture and at
f/5.6 at long taking distances (infinity). Shown
is the contrast in percentage for 5, 10, 20 and
40 lp/mm accross the height of the 35 mm film
format, for tangential (dotted line) and sagittal
(solid line) structures, in white light. The 5 and
10 lp/mm will give an indication regarding the
contrast ratio for large object structures.The
20 and 40 lp/mm records the resolution of finer
and finest object structures.
tangential structures
sagittal structures
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[%]
Aperture Stop 1.4
[%]
Aperture Stop 2.8
Y' [mm] = 21.0
[%]
Aperture Stop 5.6
Y' [mm] = 21.0
Y' [mm] = 21.0
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