HD Pentax-FA 31mm F/1.8 Limited

Wide-angle prime lens • Digital era

HD High Definition Coating is applied to the surface of lens elements. It boosts light transmission, ensures sharp and high contrast images, minimizes ghosting and flares.
FA Autofocus lens with mechanical coupling with camera and MTF program line support.

Model history

HD Pentax-FA 31mm F/1.8 LimitedA9 - 70.3m⌀58 2021 
smc Pentax-FA 31mm F/1.8 AL LimitedA9 - 70.3m⌀58 2001 

Designed for

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Features highlight

Fast
1 ASPH
1 ED
1 HLD
F.E.
9 blades
Body AF
SP
Built-in hood

Specification

Production details
Announced:February 2021
Production status: In production
Production type:Mass production
Original name:HD PENTAX-FA 1:1.8 31mm Limited
Optical design
Focal length:31mm
Speed:F/1.8
Maximum format:35mm full frame
Mount:Pentax K
Diagonal angle of view:69.8° (35mm full frame)
49° (Pentax K APS-C)
Lens construction:9 elements - 7 groups
1 ASPH, 1 ED, 1 HLD
Floating element system
Diaphragm mechanism
Diaphragm control system:Mechanical
Number of blades:9
Focusing
Closest focusing distance:0.3m
Maximum magnification ratio:1:6.25 at the closest focusing distance
Focusing method:<No information>
Focusing modes:Autofocus, manual focus
Manual focus control:Focusing ring
Autofocus motor:In-camera motor
Focus mode selector:None; focusing mode is set from the camera
Quick-Shift Focus System (QFS):-
Shake Reduction (SR)
Built-in SR:-
Physical characteristics
Weight:341g
Maximum diameter x Length:⌀65×69mm
Weather sealing:-
Super Protect (SP) coating:Front element
Accessories
Filters:Screw-type 58mm
Lens hood:Built-in petal-shaped
Teleconverters:<No information>

*) Source of data: Manufacturer's technical data.

Manufacturer description #1

Building on the long tradition of PENTAX Limited Edition lenses, RICOH COMPANY, LTD. and RICOH IMAGING COMPANY, LTD are pleased to announce three new editions to the three HD PENTAX-FA Limited lenses – featuring the original PENTAX HD coating, which now significantly enhances the lenses by minimising light reflections and ghosting.

When PENTAX first introduced the 'Limited Series' some 25 years ago, they were developed at the time of traditional SLR technology. The first thing that caught the eye were the focal length designations. A wide-angle, with 31 mm, a standard lens with 43 mm and a portrait lens with 77 mm formed a series, offering a high standard in imaging quality and technical construction. Attention to these details make these lenses special masterpieces. The original character has stood the test of time, and again provided the foundation of the new HD PENTAX-FA Limited series:

  • HD PENTAX-FA 31mm F1.8 Limited
  • HD PENTAX-FA 43mm F1.9 Limited
  • HD PENTAX-FA 77mm F1.8 Limited

Due to the sophisticated manufacturing process, each of these lenses is a masterpiece and was already the reason for many photographers to opt for this system in the days of analogue photography. A 35mm camera with three fixed focal lengths is a set-up that, even today in digital photography, represents a special approach and shows respect for traditional photography. PENTAX has decided to remain true to the philosophy that has been at the forefront of many new techniques since the beginning of camera production in Japan and is still the standard in modern photographic technology today.

And so we also find in the new series focal lengths that correspond directly to the technical calculation and are not rounded to the nearest number in order to better fit into a line-up. Also, a rather unusual feature today is the mechanical aperture selection directly on the lens with the matching depth-of-field scale above the aperture ring. A small but intricate detail are the markings on the aluminium bodies of the lenses, which make it possible to change lenses without looking.

The lens elements are treated with the multi-layer HD (High Definition) coating developed by PENTAX. Compared to conventional coatings, it offers a significantly higher light transmission with low reflection (up to 50 % compared to conventional coatings). This allows for maximum contrast and sharpness without flare and ghosting - even under difficult conditions such as backlighting. This is made possible by an exclusive PENTAX special manufacturing process, where a high-density coating is applied with high precision at the nanometre level. Which also has an extremely high hardness for superior durability.

In addition, the front lenses are provided with the original PENTAX SP (Super Protect) Coating. A fluorine coating protects the lens surface and has a repellent effect that not only repels dust, water and grease, but also makes it easier to wipe these substances off the lens surface. It is also highly resistant to abrasion and scratching and helps to keep the lens in top condition.

With the new HD PENTAX FA-Limited series, PENTAX follows its basic principles and stands for outstanding image reproduction with high detail fidelity with sharp and clear image reproduction, free from flare and ghosting.

The lenses are supplied with a built-in or corresponding screw-in lens hood and an exclusive lens cap, also made of aluminium, as well as a lens bag. They are each offered in silver (serial numbers starting with 00001) and black (serial numbers starting with 10001).

Manufacturer description #2

An exceptional lens that delivers the sharp, high-contrast, well-defined images that faithfully depict the ambience of the scene — even to the very tips of a bare tree’s branches in winter.

This lens has a 31mm focal length, which provides a slightly broader angle of view than more conventional 35mm lenses, to expand the possibilities of wide-angle photography.

This lens inherits the proven optics of the smc PENTAX-FA 31mm F1.8AL Limited, and incorporates high-grade optical components — such as glass-molded, aspherical elements and high-refraction, low-dispersion glass elements — to deliver sharp, well-defined images of small subjects, such as the very tips of a bare, leafless tree’s branches in winter.

To further improve imaging power, it also features a newly applied HD coating to produce clear, crisp images even under demanding conditions, and a completely round-shaped diaphragm to deliver a natural, beautiful bokeh (defocus) effect from open aperture to F3.5.

While retaining the outstanding optical performance of the smc PENTAX-FA 31mm F1.8AL Limited, PENTAX has upgraded the imaging power by paying meticulous attention to the details that can’t simply be measured in numbers alone, and also by applying the SP coating to the front optical element to improve the water/grease-repellent and scratch-resistant performance for easier maintenance.

Features / Specifications

High-grade lens with superb image rendition and beautiful texture

While inheriting the design concept of the Limited series, this lens was designed through a series of mechanical and numerical evaluations, as well as human assessment of test-shooting samples, to deliver an image rendition unmatched by other models.

The barrel, hood and cap are all made of high-grade aluminum, meticulously machined for an attractive appearance and beautiful texture. It also features a mount pointer with a shippoyaki (cloisonné) finish, which lets the user effortlessly and quickly mount the lens to a camera body.

HD coating for exceptional image rendition

This lens is treated with PENTAX-original HD coating.* Compared with conventional multi-layer coatings, this high-grade coating assures higher light transmittance and lower reflectance to deliver sharp, clear images free of flare and ghost images, even under such adverse lighting conditions as backlight. It elevates the imaging performance a further step up.

Round-shaped diaphragm for beautiful bokeh effect

This lens features a completely round-shaped diaphragm, which produces a natural, beautiful bokeh (defocus) effect in the images captured, while optimizing the imaging performance of the distinctive Limited-series optics contained within.

SP coating to repel dust and protect lens surface

Applied to the front optical element, the PENTAX-developed SP (Super Protect) coating effectively repels water and grease to keep the lens surface free of dust, water and oily substances. This coating is also highly resistant to abrasion and scratches, keeping the lens scratch-free.

Other features

The black model is marked with serial numbers starting with 0000001, while the silver model starts with 1000001. The lens also features an aperture ring to make best use of the range of functions featured in K-mount film-format cameras.

Typical application

landscapes, interiors, buildings, cityscapes, full to mid-body portraits, street, travel

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35mm full frame

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

Travellers' choice

Note

Among autofocus lenses designed for 35mm full-frame mirrorless cameras only. Speed of standard and telephoto lenses is taken into account.

Technical masterpiece

This Limited lens is not only capable of producing excellent photos, but also gives aesthetic pleasure to its owner.

One of the best wide-angle prime lenses

According to lens-db.com; among lenses designed for the same maximum format and mount.

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You are already on the page dedicated to this lens.

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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.

In-camera motor

Aspherical elements

Aspherical elements (ASPH, XA, XGM) are used in wide-angle lenses for correction of distortion and in large-aperture lenses for correction of spherical aberration, astigmatism and coma, thus ensuring excellent sharpness and contrast even at fully open aperture. The effect of the aspherical element is determined by its position within the optical formula: the more the aspherical element moves away from the aperture stop, the more it influences distortion; close to the aperture stop it can be particularly used to correct spherical aberration. Aspherical element can substitute one or several regular spherical elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Use of aspherical elements has its downsides: it leads to non-uniform rendering of out-of-focus highlights. This effect usually appears as "onion-like" texture of concentric rings or "wooly-like" texture and is caused by very slight defects in the surface of aspherical element. It is difficult to predict such effect, but usually it occurs when the highlights are small enough and far enough out of focus.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Canon's Super UD, Nikon's Super ED, Pentax' Super ED, Sigma's FLD ("F" Low Dispersion), Sony' Super ED and Tamron's XLD glasses are the highest level low dispersion glasses available with extremely high light transmission. These optical glasses have a performance equal to fluorite glass.

High-refraction low-dispersion elements

High-refraction low-dispersion elements (HLD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

High Index, High Dispersion elements

High Index, High Dispersion elements (HID) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Anomalous partial dispersion elements

Anomalous partial dispersion elements (AD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Fluorite elements

Synthetic fluorite elements (FL) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. Compared with optical glass, fluorite lenses have a considerably lower refraction index, low dispersion and extraordinary partial dispersion, and high transmission of infrared and ultraviolet light. They are also significantly lighter than optical glass.

According to Nikon, fluorite easily cracks and is sensitive to temperature changes that can adversely affect focusing by altering the lens' refractive index. To avoid this, Canon, as the manufacturer most widely using fluorite in its telephoto lenses, never uses fluorite in the front and rear lens elements, and the white coating is applied to the lens barrels to reflect light and prevent the lens from overheating.

Short-wavelength refractive elements

High and specialized-dispersion elements (SR) refract light with wavelengths shorter than that of blue to achieve highly precise chromatic aberration compensation. This technology also results in smaller and lighter lenses.

Blue Spectrum Refractive Optics

Organic Blue Spectrum Refractive Optics material (BR Optics) placed between convex and concave elements made from conventional optical glass provides more efficient correction of longitudinal chromatic aberrations in comparison with conventional technology.

Diffraction elements

Diffraction elements (DO, PF) cancel chromatic aberrations at various wavelengths. This technology results in smaller and lighter lenses in comparison with traditional designs with no compromise in image quality.

High refractive index elements

High refractive index elements (HR, HRI, XR etc) minimize field curvature and spherical aberration. High refractive index element can substitute one or several regular elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Apodization element

Apodization element (APD) is in fact a radial gradient filter. It practically does not change the characteristics of light beam passing through its central part but absorbs the light at the periphery. It sort of softens the edges of the aperture making the transition from foreground to background zone very smooth and results in very attractive, natural looking and silky smooth bokeh.

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

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),

where:

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

Mount

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 from the lens mount to the film or sensor can also be different.

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.

Flange focal distance

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

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.

Speed

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.

Floating element system

Provides correction of aberrations and ensures constantly high image quality at the entire range of focusing distances from infinity down to the closest focusing distance. It is particularly effective for the correction of field curvature that tends to occur with large-aperture, wide-angle lenses when shooting at close ranges.

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.

Electromagnetic diaphragm control system

Provides highly accurate diaphragm control and stable auto exposure performance during continuous shooting.

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.

Weight

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.

Filters

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

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.