Leica I (Model B)

35mm MF film viewfinder camera • Collectible



Production details:
Production type:Small-batch production: 1710 (one thousand seven hundred ten) units
Order No.:LECUR
System: Leica SM (1930)
Imaging plane:
Maximum format:35mm full frame
Imaging plane:36 × 24mm film
Fixed lens:
Original name:Leitz Elmar 1:3,5 F=50mm
Focal length:50mm
Diagonal angle of view:46.8°
Lens construction:4 elements - 3 groups
Diaphragm type:Manual
Closest focusing distance:1m
Manual focus control:Focusing lever
Leaf shutter type and speeds:Mechanical Compur, 1 - 1/300 + T, B
Type:In-lens leaf shutter
Exposure metering:None
Exposure modes:Manual
Rangefinder and Viewfinder:
Parallax compensation:-
Physical characteristics:
Weight:<No data>
Dimensions:<No data>

Manufacturer description #1

From the LEICA photography magazine (1959, No. 3):

Oskar Barnack, designer of the Leica, made the first Leitz camera more than 45 years ago as a sort of exposure meter for his movie camera. Correct exposure was hard to determine in advance, and spoiling several hundred feet of motion picture film was costly in both time and money.

So Barnack designed and made a still camera which accepted six feet of movie film and had a fixed shutter speed. It did its exposure-checking job well, and also proved to be an excellent still camera which Leitz decided to manufacture. But World War I delayed its introduction to the public. These years were a period of experimentation and development of the original camera. When the first few Leicas left the factory in 1924 they were the design later to be known in the U.S. as the Model A. They had a range of shutter speeds, focal plane shutters coupled to a film advance mechanism and non-interchangeable lenses. A new era of photographic history had begun.

Leitz' customers were shown the camera. They were mostly scientists, for the company had previously made only microscopes and scientific equipment. Many of them bought Leicas and were enthusiastic about them. And some of the scientists using the new camera asked if they could get one with an interlens shutter.

And so, at the same time that they were producing the original Model A, Leitz made up a small number of Leicas with Compur rather than focal plane shutters. These were the cameras now known in this country as the Model B.

The Model B (not to be confused with the later IIIb) was made in small quantities until 1930. It was similar to the Model A, except that it had a Compur interlens shutter rather than a focal-plane shutter which the Model A and all other Leicas feature. Some versions of the Model B had dial-set shutters while others had a rim-set type. The lens was the 50mm Elmar f/3.5, and shutter speeds were from 1 second to 1/300 second, "Time" and "Bulb." The exposure counter was located where the shutter speed dial would normally be. And what would normally be the shutter release button became a sprocket release to permit winding the film to the next exposure.

But it was the focal plane shutter, featured on the Model A which proved its superiority for general-purpose photography. It made practical the many interchangeable lenses of the Leica and set the design pace for all the top-quality 35mm cameras which have followed the Leica lead. The Model B became a part of Leica history, but not of the Leica system - a curiosity for the collector and connoisseur.

Manufacturer description #2

From the LEICA photography magazine (1961, No. 4):

Despite its quaintly olde-worlde appearance, the Model B was not the first, but the second Leica model. Introduced in 1926, and continued only through 1930, fewer than 1,500 of these front-shutter Leicas were ever made.

The raison d'etre for the Model B was, of course, its Compur blade-type shutter with speeds from 1 to 1/300th sec. Thus, it offered slow speeds below the 1/25th sec. limited of the focal-plane Model A. In the Model B the film-transport and shutter re-set functions were not combined as in the Model A and all subsequent Leicas) and a very peculiar frame-counter was mounted to the left of the winding knob (instead of being co-axial as in the other screw-mount Leicas).

After each exposure the user had to press a button in order to free the transport mechanism. Then a large metal pointer would then make an almost complete revolution before coming to rest at the appropriate number. There was no double-exposure prevention device. Model B Leicas were made with both dial- and rim-setting Compur shutters, and a very few were fitted with the self-cocking Ibsor shutter. All Model B's were equipped with the 50mm Elmar in collapsible mount.

The introduction of built-in slow speeds on the Model F doomed the Model B to early oblivion.

From the editor

Dial-set Compur from No. 5,701 in 1926 to No. 13,163 in 1929 = 638 units in total.

Rim-set Compur from No. 13,154 in 1928 to No. 50,711 = 1072 units in total.

Shutter not interlocked with film wind.

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35mm full frame

43.27 24 36
  • Dimensions: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2

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Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film.

The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.


Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Imaging sensors are sometimes smaller than 35mm film frame, and this causes the lens to have a narrower angle of view than with 35mm film, by a certain factor for each sensor (called the crop factor).

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),


CF – crop-factor of a sensor,
FL – focal length of a lens.


A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.


The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. For example, a magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size".

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

The lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value.

Semi-automatic diaphragm

The lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value.

Automatic diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/3.5 on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.


Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

A rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.


Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background.

The geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.


Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.