LEICA M6 Rangefinder Camera - Manual (Page 31)

PHOTOGRAPHY ▸ IMAGE COMPOSITION 31
IMAGE COMPOSITION
IMAGE FIELD (BRIGHT-LINE FRAME)
The bright-line rangefinder of this camera is not just a very
high-quality, large, brilliant and bright viewfinder – it also doubles as
a highly precise, lens-coupled rangefinder. All Leica M lenses with
focal lengths between 16 and 135 mm are coupled automatically
when they are attached to a camera. The viewfinder has a magnifi-
cation factor of 0.72x.
The bright-line frame is coupled with the focusing function in such
a way that the parallax – the offset between the lens axis and the
viewfinder axis – is compensated automatically.
The size of the bright-line frame corresponds to an image size of
approx. 23 x35 mm (slide format) at the shortest setting distance for
each focal length. At distances under 2 m, the film captures slightly
less than indicated by the inner edges of the bright-line frame, and
slightly more at longer ranges (see adjacent diagram). These slight
– in practical terms never important – deviations are unavoidable.
The bright-line frames of a camera with viewfinder must be adjusted
to the view angle of the focal length of the lens. The nominal view
angle changes slightly when focusing due to the changing draw-out,
i.e. the distance of the lens system to the film surface. When the set
distance is below infinity (and the draw-out accordingly greater), the
actual view angle also decreases – the lens captures less of the im-
age object. The view angle differences at greater focal lengths tend
to be larger due to the greater draw-out.
A
B
All pictures and bright-line frame positions at 50 mm focal length
A Bright-line frame
B Actual image field
Set to 0.7 m The film captures around one frame width less
Set to 2 m The film captures exactly the image field shown within the
inner edges of the bright-line frame
Set to infinity The film captures approx. 1 or 4 (vertical or horizontal) frame
width(s) more
Note
• The rectangular distance measuring field, which is brighter than
the surrounding metering field, is in the center of the viewfinder
frame. Please read the relevant sections for more information
about distance and exposure metering.