Comprehensive Pentax Lens Guide

Master the different Pentax lens series

By johnhilvert in Gear Guides on Mar 21, 2016

You may know that all Pentax K-mount lenses ever made can be attached to all Pentax DSLRs, including the mirrorless K-01 and the latest full-frame K-1. But evolutionary differences between each lens series mean that supported features may vary. This guide will make you an expert on Pentax lenses by first explaining lens terminology, then highlighting the main differences between past and present lens generations.

K-mount Lens Generation Overview

This guide covers the various generations of Pentax K-mount (bayonet) lenses since their launch back in 1975. To keep our discussion focused, we will only be considering genuine Pentax lenses, rather than third-party offerings.

Since the Pentax K-mount (bayonet) series was introduced some 40 years ago there have been several significant developments in lens capabilities since the original bayonet design.

Chronologically, the original K-Mount bayonet lenses appeared in 1975. Known as the "K" series, they were made out of metal with a solid construction and a dependable mechanical feel. But they could only be focused manually, and exposure was limited to manual mode or aperture priority.

These K-mount lenses succeeded Pentax's extensive lineup of M42 screwmount lenses from the previous two decades. The sheer speed of mounting and dismounting a bayonet lens was among the key appeals of the K-mount system. The wider diameter of the lens mount also allows for a more diverse range of optical designs. Finally, the K-mount was designed with open-aperture metering as the norm. This means that the viewfinder never darkens, even if the aperture ring is turned.

Classic Pentax KX with K-series 35mm F3.5 lens

The following year came the M series which offered the same manual focus, manual aperture functionality with smaller and lighter designs.

In 1983 came the "A" setting on the aperture ring, offering shutter priority and program operation. The camera could now automatically set the aperture if desired. This gave rise to cameras with the four basic shooting modes that we know today.

The first mainstream auto-focus lens series was known as F arrived in 1987. F lenses built on the A series with an auto-focus motor in the camera body, a drive shaft in each lens, and additional contacts on the lens mount to facilitate digital communication.

Pentax F 28-80mm
An F-series 28-80mm autofocus zoom

Improvements occurred in 1991 with the FA series supporting more extensive communication with the camera body. New features such as powered zooming were introduced on select lenses.

A budget version of the FA series, known as FA J appeared in 2003. These had no aperture ring but were instead always controlled electronically from the camera body— the net result is the same as if there was an aperture ring permanently set to "A". FA J lenses also had plastic rather than metal mounts.

In 2004 Pentax launched the first lenses designed for the smaller digital APS-C sensor called the DA series. Like FA J lenses, DA lenses have no aperture ring. Because of the smaller image circle, the DA series contains many compact lenses.

In the same year came the D FA series which was similar to the FA but with optics optimized for digital as well as film, and coatings designed to minimize ghosting and flare. Today, the D FA series contains lenses designed for full-frame digital sensors.

Pentax K-1 with 15-30mm Pentax K-1 with the latest HD Pentax-D FA 15-30mm F2.8 ED SDM WR lens

In 2008 came the DA L series, with budget versions of popular entry-level DA zooms such as the 18-55mm or 55-300mm. DA L lenses are often matched with entry-level Pentax DSLR bodies.

While no new lens series have been launched since then, lens technology continues to evolve at a very rapid pace.

All currently-available Pentax lenses are members of the following series:

DA (digital, APS-C crop format);
DA L (affordable digital kit);
D FA (full-frame, digital optimized); and
FA (full-frame, film-era) series.

Decoding Pentax Lens Names

It is important to be able to make sense of the many labels found on a lens. A Pentax lens name is generally engraved as follows:

_{Coating | Series | Largest F-stop(s) | Focal length(s) | Suffixes}

The F-stop and focal lengths are occasionally switched.

Let's take a typical weather-sealed Pentax kit lens as an example. Below we have the SMC (coating) Pentax (brand) DA L (series) 1:3.5-5.6 (largest F-stop at 18mm and 55mm) 18-55mm (focal lengths) AL WR (suffixes).

Decoding the names

Since engraved names vary from era to era, we standardize lens names using a format that more clearly identifies the focal length and aperture. This particular lens is listed as the SMC Pentax-DA L 18-55mm F3.5-5.6 AL WR. We use this format site-wide, so the aperture will always come after the focal length / zoom range.

Why Coat the Lens

Optical coating means less flare, less ghosting and better contrast. The prefix SMC or HD indicates the type of coating. SMC stands for Super-Multi Coating. SMC was introduced back in the 1960's to cover the original M42 screw mounts. Improved over time, the most advanced version of this coating is now called HD (High Definition) and introduced in 2012. With the exception of a handful of old budget lenses, all legacy Pentax K-mount lenses have SMC coating. Modern lens have either SMC or HD and oftentimes additional protective or performance-enhancing coatings.

Visible multi-coating

If you want to delve into the finer points, check out our in-depth article on lens coatings.

The prevalence of the term "SMC" can sometimes lead to confusion. When categorizing different Pentax lens names, it is best to ignore the coating, as it does not directly determine the lens series. Rather, each lens series has a distinct set of mechanical features (i.e. autofocus) or physical characteristics that determine the series.

Lens Terms and Suffixes You Need to Know

AL: Aspherical Lens. Special lens elements that improves the optical quality. Particularly valuable in wide angle lenses, and fairly common in modern optical designs. AL elements generally reduce the total number of elements in an optical design.

AW: All Weather. This signifies the highest degree of sealing against dust and rain. Don't confuse this with WR: These are weather resistant which are sealed so that they better withstand use in light rain and blowing dust. WR and AW both designate weather-sealed lenses. Non-star lenses that are designated WR use a "simplified weather-resistant construction" to protect against ingress of water. DA* lenses, although not indicated as such in the lens name, are considered AW (newer boxes for DA* lenses are often marked as such) and are "dust-proof and water-resistant because each part is individually sealed" offering a higher level of protection against environmental conditions than the WR designation indicates.

DA lenses (with a few exceptions) feature a Quick Shift focusing system that allows the focus to be fine tuned with the focusing ring on the lens without first setting the camera focus selector to "MF" (manual focus).

DA L lenses are a light weight edition of their DA counterparts. They have a bayonet mount made of plastic rather than stainless steel. They do not have the quick shift focusing capability.

DA* (pronounced “Dee Ace Tar”) Lenses: The DA series includes a number of "star" lenses (DA*) with top notch optical and mechanical engineering designed for professional use. All DA* lenses have the Quick Shift focusing system. They are weather sealed even though they lack the WR suffix. Many other lens series also contain star lenses (i.e. D FA*, FA*, etc.).

D FA lenses are modern lenses designed for full-frame cameras. Other lens series include FA, FA J, F, A, M, and K, as described in the sections to follow.

DC or SDM: Lenses with the DC or SDM designation feature a built-in autofocus motor. All current DSLRs take advantage of this motor when available, instead of the screw-drive mechanism.

In-lens motors are considerably quieter than screwdrive; they also focus more smoothly and some operate more quickly.

Some DA lenses are DC/SDM-Only (KAF3 mount), such as the SMC Pentax-DA* 55mm F1.4 SDM prime lens and SMC Pentax-DA 17-70mm F4 zoom lens. These lenses lack the traditional screw drive autofocus coupler and will not be able to autofocus on cameras launched prior to the K10D (2006). Incompatible cameras include the *ist D / DS / DS2 / DL / DL 2, the K100D, and the K110D.

ED: Extra-low Dispersion. Special glass material which helps reduce chromatic aberration. Particularly valuable in telephoto lenses. Typical in modern lens designs.

IF: Internal Focusing. Focusing is achieved by moving lens elements within the lens. The lens barrel doesn't move. IF lenses generally focus faster than ordinary lenses.

Note that certain lenses also zoom internally, such as the DA* 50-135mm and D FA* 70-200mm. Interestingly, there is no designation for this.

Limited: premium lenses with metal barrels and a focus on compactness.

RE: Lenses with the RE suffix can retract for a smaller form factor when stowed. Due to this design, manual focus is carried out by the AF motor in the lens. These lenses cannot be focused at all on DSLRs that do not support DC or SDM, nor will they focus on film cameras.

XS: Lenses with an exterior design by Mark Newson matching the Pentax K-01. The DA 40mm XS is currently the only XS lens.

Current Pentax Lens Series

Now, let's jump in and take a closer look at each individual lens series.

Three main Pentax lens series are currently in production: DA, DA L, and D FA. In addition, a handful lenses from the film-era FA series continue to be available.

SMC Pentax-DA 50mm F1.8

DA Series

Digital-Era APS-C Lenses

With a total of 20 zooms and 17 primes as of early 2016, the Pentax DA series is the largest current Pentax lens series. DA lenses are designed for crop format (APS-C) digital SLR camera bodies. The series was launched in 2004 alongside the Pentax *ist D.

All DA lenses support autofocus and automatic aperture control. Pentax DSLRs also support in-camera lens corrections (vignetting, distortion, etc.) for DA lenses. DA lenses do not have aperture rings, as DSLRs can control the aperture setting electronically.

A key new feature launched with the DA series is quick shift, or the ability for the user to manually override the focus setting at any time simply by turning the focusing ring. Thanks to an internal clutching mechanism in each DA lens*, manual focus is possible even when the AF/MF switch on the camera is set to AF. On earlier lenses, turning the focusing ring while in AF mode would strain the gears inside the lens, thus causing potential damage.

Other features that originally debuted in the DA series include weather sealing and silent autofocus.

*budget-oriented DA lenses lack quick shift, including the DA 50mm F1.8 and DA 35mm F2.4

The DA series has two key sub-series:

DA* lenses are professional-grade with wide apertures
- silent autofocus
- weather-sealed
DA Limited lenses have compact, stylish metal barrels and premium image quality

The DA 40mm Limited "pancake" is only 1.5cm long

The characteristics of lenses that do not fall within either of these sub-series are not necessarily homogeneous. DA lenses vary from being quite basic to being packed with the latest optical and mechanical technologies; hence, interpreting the various components of each lens name is particularly important.

DA lenses are designed to only cover the APS-C (1.5x crop) image circle. However, select lenses in fact cover a much larger image circle. Pentax literature states that the DA* 200mm, DA* 300mm, and DA 560mm telephoto primes are full-frame compatible. We plan to test all remaining DA lenses empirically in the near future, but at this time we do not recommend other DA lenses for the full-frame Pentax K-1.

Click here to view current DA lenses

DA series highlights:

APS-C image circle
Autofocus (silent or screwdrive)
Some are weather-sealed
Automatic aperture control, no aperture ring
Latest lens technologies
Current series

SMC Pentax-DA L 18-55mm

DA L Series

Six entry-level kit lenses are marketed under the DA L series. DA L lenses are designed to be affordable, and thus have a more limited feature set compared to DA lenses. These lenses are typically bundled with entry-level and mid-range DSLRs. Flagship models tend to come with a DA lens.

All DA L lenses are optically identical to a counterpart within the DA series. They all have autofocus and automatic aperture control, and they support lens corrections.

The lens mount on DA L lenses is made of plastic rather than metal. DA L lenses lack quick-shift and are typically not sold with cases or hoods (though these are available separately). DA L lenses also don't have an engraved distance scale.

Some DA L lenses do have weather sealing (WR designation).

Click here to view current DA L lenses

DA L series highlights:

Budget-oriented zoom lenses
Screwdrive autofocus
Optics identical to DA counterparts
No quick-shift or distance scale
Hoods sold separately
Plastic lens mount
Some are weather-sealed

SMC Pentax-D FA 50mm F2.8

D FA Series

Digital-Era Full-Frame Lenses

The D FA lens series made its debut in 2004, just as the majority of the FA series was being discontinued. Originally, D FA lenses were marketed as digital-optimized lenses that were also designed for film cameras.

Due to the quick demise of film SLRs, today D FA lenses are designed and optimized for full-frame digital sensors (namely the Pentax K-1). While early D FA lenses had aperture rings, they were quickly dropped in subsequent lenses due to their redundancy.

Like DA lenses, all D FA lenses offer autofocus and automatic aperture control, and they support in-camera lens corrections.

There are 7 current lenses in the D FA series, one of which is badged as a premium D FA* (D FA star) lens.

Since the full frame format caters more directly to professional photographers, D FA lenses tend to be generously packed with Pentax's latest optical and mechanical technologies. For example, all D FA zooms (as of 2016) are weather-sealed, silent-focusing (SDM or DC), and HD-coated.

Of course, D FA lenses are also perfectly usable on APS-C format bodies. The oddball D FA 100mm F2.8 WR Macro even resembles a DA Limited lens in terms of physical appearance.

Click here to view current D FA lenses

D FA series highlights:

Full-frame image circle
Autofocus (silent or screwdrive)
Most are weather-sealed
Automatic aperture control; no aperture ring (except for early macro lenses)
Latest lens technologies
Current series

SMC Pentax-FA 50mm F1.4

FA Series

Second-Generation (Film Era) Autofocus

With 22 prime lenses and 20 zooms, the Pentax FA lenses comprises the largest Pentax film-era lens series. Today, only 5 FA primes remain in production.

Thanks to aperture automation and screwdrive autofocus, the FA series is very similar to the F series (see below) in terms of functionality. FA lenses work just like modern DA lenses on Pentax DSLRs (the aperture ring should always be kept in the "A" setting), though most do not support in-camera lens corrections.

The FA series improved on the electronic communication capabilities of the F series. As a result, Pentax DSLRs with the MTF program line can be configured to shoot at optically optimal aperture values. Select FA lenses were also fitted with Power Zoom; while this feature never gained traction, power zoom contacts on the lens mount later evolved to instead be used for silent autofocus on modern DA and D FA lenses.

There are 11 professional-grade FA* (FA star) lenses within the FA series; to date the largest Pentax star lineup. In addition, the FA series gave rise to the term "Limited", which denotes compact lenses with an old-fashioned compact metal barrel and a focus on premium image quality.

Key members of the FA* series include the FA* 85mm F1.4 portrait lens, FA* 80-200mm F2.8 zoom, and FA* 300mm F2.8 fast telephoto prime. A distinguishing feature of FA* lenses is an AF/MF clutch operated by sliding the focus ring back and forth.

The FA Limiteds— 31mm F1.8, 43mm F1.9, and 77mm F1.8— are sometimes commonly referred to as the "three amigos".

Click here to view current FA lenses

FA series highlights:

Screwdrive autofocus
Enhanced electronic communication
Automatic aperture control; aperture ring
Full-frame image circle
Mostly discontinued

Discontinued Lens Series

The series below are no longer in production, but many of these legacy lenses continue to be popular on the second-hand market. Furthermore, understanding the history of Pentax lenses gives us insight into the origins of modern technology through early concepts.

Each legacy lens series includes an overview of DSLR compatibility.

SMC Pentax-FA J 28-80mm F3.5-5.6

FA J Series

Third-Generation (Late Film Era) Autofocus Zooms

The last Pentax film SLR, the *ist, was launched in 2003 just as the digital *ist D was about to make its debut. Both of these cameras allowed for control of the aperture setting through the camera body itself, so an aperture ring on the lens was no longer necessary.

In light of this, Pentax launched the FA J lens series in 2003. These lenses could potentially be made cheaper since the hardware associated with the aperture ring could be omitted. The trade-off is that these lenses are not backwards-compatible with SLRs that do not support A-type lenses. To further reduce costs, Pentax decided to employ plastic mounts.

FA J lenses worked just like FA lenses with the aperture ring permanently set to the "A" position.

Since Pentax decided to stick with the APS-C sensor format, the FA J series was short-lived, with just 3 lenses. All FA J lenses were discontinued in 2006, though they ended up influencing future digital designs.

DSLR Compatibility and Usage:

FA J lenses work just like autofocus FA lenses. There are no restrictions in terms of metering or functionality on digital bodies.

Click here to view all FA J lenses

FA J series highlights:

Screwdrive autofocus
Electronic communication with camera
Automatic aperture control; no aperture ring
Full-frame image circle

SMC Pentax-F 50mm F1.4

F Series

First Generation Autofocus

The Pentax F lens series was launched alongside the Pentax SF-1 autofocus DSLR body in 1987. The main new feature of this series is support for camera-powered screwdrive autofocus through a mechanical drive shaft in each lens. In addition, it was now possible for lenses to communicate with camera bodies electronically (i.e. to transmit the current focal length or focus setting).

This was the first Pentax lens series to include more zooms (11) than primes (9).

In terms of aperture automation, the F series works just like the A series; each lens has an "A" setting on its aperture ring.

Most F-series lenses were discontinued in 1991 and replaced by cosmetically updated "FA" versions. Some lenses, such as the SMC Pentax-F 17-28mm Fisheye, never saw a replacement and thus continued being available until the early 2000's, which marked the end of the film era.

DSLR Compatibility and Usage:

F lenses work just like autofocus FA lenses. There are no restrictions in terms of metering or focusing on digital bodies.

There is one small exception: the SMC Pentax-F Soft 85mm F2.8 has no "A" setting on the aperture ring. It has a manual diaphragm below F6.7 and works like an M or K series lens at F6.7 and above. This is because because image softness is controlled by the aperture ring and it would be meaningless to let the camera decide the setting. Note that this caveat also applies to FA-series soft lenses.

Click here to view all F lenses

F series highlights:

Screwdrive autofocus
Electronic communication with camera
Automatic aperture setting
Full-frame image circle

SMC Pentax-A 50mm F1.4

A Series

Manual Focus with Aperture Automation

In the 1980's, electronics slowly started replacing analog components in SLR bodies. Pentax launched the A lens series to support automatic aperture control (program and shutter priority mode) on these new SLRs.

In total, the A series consisted of 28 prime lenses and 11 zooms. Of those lenses, a total of 9 were designated as A* (A star), or professional-grade. While most A lenses were discontinued in 1989, some continued being produced until the early 2000's.

Thanks to evolving optical technology, the A series also saw the debut of wide-aperture lens designs, such as the A* 85mm F1.4 and A* 300mm F2.8. The A series is thus an excellent source for affordable wide-aperture telephoto lenses.

Plastic components slowly started replacing the classic metal barrels, namely on cheaper lenses in the A series, such as the A 50mm F2.0.

DSLR Compatibility and Usage:

Pentax A lenses work just like modern lenses in terms of metering. All exposure modes offered by current DSLR bodies will thus be supported. Thanks to this, A lenses are much more convenient to shoot with than M and K lenses, though they are all still manual focus.

On DSLRs, the aperture ring should always be placed in the "A" position; not doing so will cause A lenses to behave like M and K lenses.

Click here to view all A lenses

A series highlights:

Automatic aperture setting
Manual focus
Full-frame image circle

SMC Pentax-M 50mm F1.4

M Series

Second Generation Manual Focus

The Pentax M series was the second series of Pentax bayonet lenses. It consisted of 22 primes and 8 zooms, most of which were launched in the late 1970's and continued being produced alongside lenses from the K series through the mid 1980's.

Lenses in the M series are generally smaller and lighter than their K series counterparts. This series set a precedent for Pentax's focus on compactness.

The M series was also the first Pentax lens series to start designating lenses as professional-grade using a single star. The M* 300mm F4 was the sole member of the "M star" sub-series.

DSLR Compatibility and Usage:

M lenses are manual focus and have no "A" setting on the aperture ring, so the aperture must be set manually by the user using the aperture ring itself.

On Pentax DSLRs, a relatively simple procedure known as stop-down metering must be used in order for the camera's light meter to correctly set the shutter speed. See our guide to using K lenses on Pentax DSLRs for an in-depth explanation of this procedure.

Most Pentax film SLRs, on the other hand, can sense the position of the aperture ring and can thus provide immediate light meter readings without the need for this extra step.

Click here to view all M lenses

M series highlights:

Generally smaller than K lenses
Manual focus
Manual aperture
Full-frame image circle

SMC Pentax 50mm F1.4

"K" Series

First Generation Manual Focus

The original series of Pentax K-mount bayonet lenses was launched in 1975 and continued until the mid 1980's. It consisted of 34 prime lenses and 7 zooms. These lenses were designed for 35mm film and thus support the modern full-frame image circle.

This series is commonly referred to as the original "K" lens series, despite the lack of a K in the official lens names. Lenses were simply labeled "SMC Pentax".

DSLR Compatibility and Usage:

Same as M lenses; see above. Like M lenses, K lenses are manual focus and require the user to manually set the aperture value using the aperture ring. These two lens series operate identically on DSLR bodies.

Click here to view all K lenses

K series highlights:

The original K-mount series
Manual focus
Manual aperture
Full-frame image circle

Takumar-A 28-80mm

Legacy Budget Lenses

In the 1980's, a host of budget-oriented lenses was launched to supplement the main Pentax lens lineup. These affordable lenses shared the same mounts and features as their more expensive counterparts, but they all lacked the SMC multi-coating. As such, their lens names differed as follows:

Budget M series → Takumar (Bayonet)
Manual focus, manual aperture
Budget A series → Takumar A or Pentax-A
Manual focus, auto aperture
Budget F series → Takumar F or Pentax-F
Autofocus, auto aperture

Click here for a complete listing of legacy budget lenses. Due to inferior optical performance, most of these lenses attract little attention today.

Lens Feature Overview

Now that you know about the different Pentax lens series and understand key terminology, the table below should allow you to gain a quick overview of the features supported by each series.

	Current lenses				Legacy lenses
	D FA	DA	DA L	FA	FA J	F	A	M / K
Autofocus
Quick shift		*1					N/A	N/A
Auto aperture
Aperture ring	*2
Lens corrections				*3
Lens ID in EXIF
Supports DSLRs
Full frame		*4

*1 except lenses with plastic mounts
*2 except for the D FA 50mm and 100mm macros
*3 select DSLRs have in-camera profiles for FA Limiteds and select other lenses
*4 some exceptions apply; see here

Conclusion

Pentax users are fortunate to have a plethora of lens choices available to them, both new and old. Legacy lenses are not to be overlooked: some lenses are an exceptional value, while others have tried-and-tested optics that deliver even on today's latest bodies. We hope that this article has shed some light on the different Pentax lens series and clarified some of those confusing acronyms.

For personalized lens advice, don't hesitate to post in our Pentax lens forum.

If you're interested in further deepening your knowledge of Pentax lenses, we to invite you to read on!