The Leica M8 has a smaller image field compared to the Leica M6 (or nowadays Leica M9, M Monochrom, M-E, Leica M (Type 240) due to the smaller size of the sensor .
In the following, some facts for different focal lengthes are given.
As the Leica M8 is compatible with the lenses used of Leica M6 (or M9, M Monochrome, M (Type 240) etc.), the smaller sensor limits the image field or the angle of view, but does not affect the depth of field of the lense.
This circumstance of the smaller image field has given different names. In the Leica M8 manual, it is called extension factor. In other literature or in many webblogs, it is also called crop factor.
For me it is a limitation of the angle of view, at least in most cases of lenses.
Leica M8 Manual: The extension factor
“The nominal focal lengths of Leica M lenses are based on the 35mm-format, i.e. on a film format of 24x36mm. In comparison, with its 18x27mm, the sensor in the LEICA M8 is somewhat smaller though – by a factor of 0.75. Therefore, when used on the LEICA M8, these lenses have angles of view corresponding to lenses with focal lengths that are longer by a factor of 1.33 (1.33 = reciprocal of 0.75). This has the respective effects on their perspective, but not on their depth of field, which, with the LEICA M8, can also be read directly off the lens (see the lens instructions for more details).
The bright-line frame in the viewfinder of the LEICA M8 of course always shows the “correct” field of view for this camera, i.e. it takes account of the increased focal length. You can therefore compose your pictures in the normal way, just as for other cameras in the Leica M series … .” [Leica M8 Manual P. 87]
Angle of View comparision
|Focal Length||Angle of View|
|approx. extended focal lenght||diagonal||horizontal||vertical|
|16 mm||21 mm||107°||90°||97°||80°||74°||59°|
|18 mm||24 mm||100°||84°||90°||74°||67°||53°|
|21 mm||28 mm||92°||75°||81°||65°||60°||46°|
|24 mm||32 mm||84°||74°||53°|
|28 mm||37 mm||75*||60°||65°||51°||46°||36°|
|35 mm||47 mm||63°||50°||54°||42°||38°||29°|
|50 mm||67 mm||47°||36°||40°||30°||27°||20°|
|75 mm||100 mm||32°||24.4°||27°||20.4°||18°||13.7°|
|90 mm||120 mm||27°||20.4°||23°||17.1°||15°||11.4°|
|135 mm||180 mm||18°||15°||10.2°|
|Zenitar Fisheye 16mm||180°|
angle of view for various focal lengths (based on specs)
last update: 25.3.2015