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two LEICA APO-EXTENDER-R models are both inserted between the camera and
lens, and extend its focal length by a factor of 1.4 and 2 respectively.
They are specially
designed for use with the Leica APO lenses, so their image quality is
fully retained with the extender in use, though they can also be used with
various other Leica R lenses.
There are number of
aspects to note in this respect: The LEICA APO-EXTENDER-R 2x, constructed
from seven elements in five groups, is designed for lens units with a
maximum aperture of 1:2 or smaller, and they reduces the aperture by 2
f/stops.
So when used with the
LEICA SUMMILUX-R 50 mm f/1.4, for example, there is no increase in light
compared to using a lens with a 1:2 aperture number. This means an
exposure compensation of -1EV is needed, and the Summilux should be
stopped down to at least to f/2.
The LEICA APO-EXTENDER-R
1.4x, is of five-element construction and is designed for lenses with maximum
apertures of 1:2.8 and below, and reduces the effective aperture by one stop.
Lenses with a maximum aperture of 1:2 should therefore be stopped down by
approximately one to two stops.
The distinctive
protruding front element of the LEICA APO-EXTENDER-R 1.4x limits the number of
usable lenses to a greater extent than the LEICA APO-EXTENDER-R 2x, as the table
below shows.
Both extenders
offer fully automatic diaphragm operation, and are also useful aids in close-up
shooting, since they not only extend the focal length by their respective
factors, but also enlarge the magnification by a corresponding amount, while
retaining the focusing adjustment range of the lens.
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