Before you start to identify an early Leica, you must be aware that the factory would provide conversions, upgrading an older model camera to a newer model. So occasionally you will find a camera that doesn't quite meet all of the criteria for a given model, and/or is of the wrong serial number range. These are not terribly rare, nor especially valuable.
The other misleading thing about Leicas are the model designations. They started off with letter designations, then switched to a combination of Roman numerals and letters.This can be confusing because a model III is also known as a model F. Sometimes you'll find it described as a model III (F), yet there is another model IIIf which is different.
Once they had multiple models available, they had a method to their madness. I series cameras have no rangefinder and no slow speeds. Some did not even have viewfinders. II series cameras have rangefinders, but no slow speeds. III series have both rangefinders and slow speeds. After the postwar reintroduction of the C series cameras, the letter was preceeded by a number identifying the features, such as a IIC, a C series camera with rangefinder, but no slow speeds.
The first three models of Leica would fall into the Leica I series, although at that time there was nothing else.
Leica A
The first model of Leica is the model A. The lens is fixed to the camera, and the infinity lock is a large hockey stick shaped arm on the front of the camera. There is no rangefinder. The camera has a focal plane shutter, speeds 20-500, plus Z (Zeit, or time), set on a dial on the top of the camera.
For more information, go to Leica A cameras
Leica B
To provide slower shutter speeds, the focal plane shutter was replaced in the Model B with a Compur shutter in the lens.
For more information, go to Leica B cameras
Leica C
The third model of Leica had removable lenses. The hockey stick lens lock is gone. This is the Leica C. It also has the short rewind knob that does not pull up for rewinding.
For more information, go to Leica C cameras
Leica D
Next came the Leica D, the first Leica with a built in rangefinder, but no slow speed dial on the front. This camera is the first of the II series, and is also referred to as the Leica II. It can be distinguished from later II series by the lack of a patch on the front where the slow speeds would be.
For more information, go to Leica D cameras
Leica E
The Leica E is a Leica C with a rewind knob that pulls up like the Leica D has. This is the last I series with a viewfinder.
For more information, go to Leica E cameras
Leica F
The new top of the line camera was the Leica F, which had a slow speed dial, and was the only camera with slow speeds and a top speed of 1/500. This was the first of the III series, and also known as the Leica III.
For more information, go to Leica III cameras
Leica G
The Leica IIIa was the first model to have 1/1000 for a top speed, and have the finder windows separated on the back of the camera. This camera was known as the Leica G in the old system.
For more information, go to Leica IIIa cameras
Leica Reporter
Two models of Leica that were based on the F and the G, but designed for 250 exposures of film are the FF and GG. The are referred to as "Reporter" models, and can be identified by the oversize ends, and the counter that goes up over 200.
For more information, go to Leica Reporter cameras
Leica IIIb
The Leica IIIb is the first model without a single letter designation. The finder windows on the back are moved next to each other, and share a common bezel, and is the last to have a rangefinder cover that is a separate piece from the top cover.
For more information, go to Leica IIIb cameras
Leica IIIc, IIc and Ic
The first cohesive group of cameras is the c series (the IIIc, Iic and Ic). These all have the new top plate and rangefinder cover all one piece, and the last without flash synch.
For more information, go to Leica IIIc family of cameras
Leica IIId
Actually produced before the IIIc, the IIId is a IIIc with a self timer added to the front.
For more information, go to Leica IIId cameras
Leica IIIf, IIf and If
The next series is the f series. These have flash synch, and are readily identified by a ring of numbers on the top plate around the shutter speed dial. These are the flash delay settings for various types of bulb flash.
For more information, go to Leica IIIf family of cameras
Leica IIIg IIg and Ig
The final series is the g series. The IIIg has a extra large viewfinder with a fourth window on the front. This window illuminates the frame lines visible in the viewfinder. The IIg was not commercially available. The Ig is the only model of I series camera with a self timer.
For more information, go to Leica IIIg family of cameras
Leica 72
Leica also built a small number of half frame cameras, the Leica 72. These are easy to identify by the "18X24" engraved on the top plate.
For more information, go to Leica 72 cameras
