Asahi Bellows-TAKUMAR 100mm F/4

Macro lens • Film era • Discontinued


Model history (2)

Asahi Bellows-TAKUMAR 100mm F/4 [360, 43600]For bellowsP5 - 3⌀49 1964 
Asahi Super-Multi-Coated Bellows-TAKUMAR 100mm F/4 [43601] [Mod. M42]For bellowsP5 - 3⌀49 1971 

Features highlight

8 blades


Production details
Production status: Discontinued
Order No.:360
Original name:Asahi Opt. Co. Bellows-Takumar 1:4/100
System:Asahi Pentax M42 (1957)
Optical design
Focal length:100mm
Maximum format:35mm full frame
Mount and Flange focal distance:M42 [45.5mm] (Bellows)
Diagonal angle of view:24.4°
Lens construction:5 elements in 3 groups
Diaphragm mechanism
Diaphragm type:Preset
Aperture control:Preset ring + Aperture ring
Number of blades:8 (eight)
Closest focusing distance:<No data>
Maximum magnification:<No data>
Focusing modes:Manual focus only
Manual focus control:None; focusing with bellows
Physical characteristics
Maximum diameter x Length:⌀55.5×36.6mm
Filters:Screw-type 49mm
Lens hood:Screw-type round
Teleconverters:Not available
Sources of data
1. The Ultimate Asahi Pentax Screw Mount Guide 1952-1977 book by Gerjan van Oosten (1999).
2. Lenses for the Honeywell Pentax booklet (October, 1965).
3. Asahi Pentax Takumar interchangeable lenses operating manual (PUB. 06081).
4. Asahi Pentax Takumar interchangeable lenses operating manual (red cover).
5. Complete system of photography: Asahi Pentax lenses and accessories booklet (PUB. 63008).
6. Honeywell Photographic Products booklet (March 1969).
7. Honeywell Pentax cameras, lenses, and accessories booklet (March 1971).
8. Honeywell Photographic GSA Catalog and Price List (December 1, 1970 through November 30, 1971).
9. Asahi Pentax Spotmatic II operating manual (PUB. 06461, early).
10. Asahi Pentax SV & S1a operating manual (PUB. 61008, 18 pages).
11. Honeywell Pentax H3v/H1a operating manual.
12. Honeywell Pentax SL operating manual (August 1969).
13. Honeywell Pentax SP 500 operating manual.
14. Honeywell Pentax Spotmatic II operating manual.
15. Honeywell Pentax Spotmatic operating manual (May 1967).
16. Honeywell Pentax Spotmatic operating manual.

Manufacturer description #1

This 100mm lens is designed for use on a bellows, but it allows you to photograph from infinity to as close as 6 inches from a subject. With it you can take pictures of distant mountain scenes or greater than life-size negatives of stamps or coins with equal ease and clarity. It is, therefore, a new and valuable tool for both amateur and professional photographers.

The Bellows-Takumar is particularly suited for use with the Pentax Bellows II on the Spotmatic camera, which will automatically compensate for the exposure factors involved in extreme close-up work. The focal length of the lens not only provides ample image size and convenient working distances for tightly cropped photographs of small objects, but also makes it ideal for portraits. The photographer who owns the Bellows-Takumar lens will find himself putting it to a range of uses he never thought possible.

Manufacturer description #2

Min. focus 6 inches from lens rim when used on Pentax Bellows II.

Bellows unit II: this dual-track unit provides maximum stability, outstanding design and rugged reliability. With precise, firm control, it may be locked in any position. Has oversized focusing knob for increased sensitivity and ease of focusing. 3.2x magnification at maximum extension with standard 55mm Takumar lens and 3.58 with 50mm f/1.4.

Manufacturer description #3

This really versatile lens combines all the qualities of a macro lens with the efficiency of a long-focus optic. Since you can expand or contract the Bellows freely, you can focus continually from infinity to magnified close-up. This is the ideal lens for precision shots requiring long focusing and for photographing live animals from a distance.


This is a long focal length macro lens to be used together with the Bellows or Auto-Bellows Unit.

Emphasis has been placed on precision at the expense of brightness: distortion has been reduced to practically nil and the same fine results are obtained at all distances down to magnified close-ups. Combined with the Bellows Unit, photography from infinity down to life-size close-ups is possible, while with the Auto-Bellows magnification of up to 1.32 is possible. Thus you can take distant scenics and superb close-ups with one and the same lens. The 100mm focal length makes this lens ideal for studies of insects, small animals and other subjects which are difficult to approach and also for close-ups under difficult lighting conditions : the required magnification is obtained without having to bring the lens close in. This lens also has fine perspective characteristics.

Main uses

Ideally suited to studies of insects, the natural perspective qualities of this lens also make it a fine choice for all close-ups taken from some distance from the subject.

Manufacturer description #4

Specifically designed for use in conjunction with the focusing bellows unit this short mount 100mm f4 lens constitutes an impressive specialist Tele-Macro lens, focusing from life size to infinity. The superior high resolution performance is due to the fact that again this lens is computed for close-up and macrophotography.

Furthermore, the lens will still provide critical definition and resolution for all normal subjects. The fact that one can work with a comfortable lens/subject distance relationship when photographing insects or small animals and the like is particularly valuable when a closer approach is not possible or desirable for whatever reason. Further, it eases the sometimes difficult problem of establishing adequate frontal lighting.

Distortion is virtually non-existent. The diaphragm is pre-set with a 'click' stop indent control ring and the lens accepts standard 49mm filters.

Principal Uses

Ranging from specialist Macro studies, but including a wide range of general purpose applications with all the advantages offered by this unusual lens.

Typical application


Slow full-frame macro lens • Professional model (Top class)

Professional model (Top class)

  • Specialized tool
  • Combination of focal length and closest focusing distance meets professional demands

Genres or subjects of photography (2):

Macrophotography • Product photography

Recommended slowest shutter speed when shooting static subjects handheld:

1/100th of a second

Alternative in the Asahi Pentax M42 system

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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".

Modified M42 mount

The mount has been modified by the manufacturer to allow exposure metering at full aperture.

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/4 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.