[Test – EN] Pentax DA★ 50-135 mm f/2.8 ED [IF] SDM (2021)

The review of the SMC Pentax-DA ★ 50-135 mm f/2.8 ED [IF] SDM was performed with a Pentax K-3II body - Test en français ici

This lens Pentax DA ★ 50-135 mm f/2.8 ED [IF] SDM was already tested by Pentaxklub in February 2016. However, we announced in August 2020 that some lenses would have a new review. Now it is the turn of this zoom lens to be submitted a second time to our test procedures. Currently, unlike the DA ★ 16-50, no successor or replacement to this 50-135 has been announced. The 50-135 therefore remains one of the flagships in the Pentax APS-C lens catalog.

Overview of  the SMC Pentax-DA ★ 50-135 mm f/2.8 ED [IF] SDM lens

General information

The focal range of this zoom, on APS-C cameras, is roughly like a 75-205 mm on FF body. And its aperture f/2.8 would then correspond to an f/4.2. If you know what I mean… This is one of the most popular focal length ranges for photographers. Note that for the full format, Pentax offers 2 more or less equivalent zooms in terms of field of view (DFA ★ 70-200/2.8 and DFA 70-210/4, not really what is generally called « entry-level »). The brand also offers, for the APS-C format, a DA 50-200/4-5.6 ED WR zoom, much more « consumer » and often supplied as a kit lens in the past.


Note that it benefits from an internal focus device (IF, Internal Focus) that prevents it from lengthening during focusing, unlike its « little brother », the DA ★ 16-50 f/2.8.

If it is used with an SDM-compatible digital camera (1), this AF motorization is automatically activated. However, if it is used with a non-SDM compatible digital camera, the AF motor of the camera can be used to focus (screw drive).


The indication does not appear in its « official » name, but it is a « Dust and Weather resistant » lens, built to be usable in difficult conditions: dust, rain, snow. However, it is not designed to operate underwater. This use requires dedicated equipment

Hood and filter mount

The supplied tulip-shaped hood has the traditional (at Pentax) trapdoor that allows a polarizing filter to be operated even when it is in place. By the way, when the hood is correctly mounted, this trapdoor must be located on the bottom of the accessory and not on the top. Therefore, beware of the risk of loss!

Please note, moreover, that the filter mount (67 mm diameter) does not rotate when changing focal length and focusing (internal focus, « IF »)

Getting started with the DA ★ 50-135 mm f/2.8

The Pentax DA ★ 50-135 mm f/2.8 weighs 685 g (about 1.5 pound). This is not an insurmountable weight in common use. It is difficult to make comparisons with similar lenses of other brands: the competition has totally disappeared. There was once a Sigma 50-150 in K-mount, but it hasn’t been around for several years.

There is no discomfort in using this 50-135 on any Pentax APS-C frame. The body/lens balance is very good and the weight of the set is very acceptable for most photographers. One important note: there is no way to use it on an FF camera other than in APS-C crop mode. The optical circle is that of an APS-C and does not cover the 24×36 sensor. It is however possible to use it in crop mode 1:1. We will come back on this point a little further.

Its minimum focusing distance (1 m – about 3.2 ft) is fine, but does not allow the practice of proxi-photo, except if you « crop » the final image. This is because the magnification ratio is about 1:5 (0.17x).

The following photos were taken with a K-3 II, approximately at the minimum focusing distance. The height of the mug is very exactly 10 cm (about 4 inches).


1/80s - f/9 - ISO 400 à 50 mm
1/15s – f/9 – ISO 400 at 50 mm –  -1EV


1/60s - f/9 - ISO 400 à 135mm
1/30s – f/9 – ISO 400 at 135 mm



Handling : 10

Main technical data about the DA ★ 50-135 mm f/2.8

Technical data (click here)
PENTAXsmc PENTAX-DA★50-135mm f/2.8 ED [IF] SDMMonture KAF2
KAF2 Mount
Focal lengths
50mm à (to) 135mm
Equivalent 35mm sur un APS-C
35mm equivalent on an APS-C camera
76,5mm à (to) 207mm
Angle de champ / de vue

Angle of view
31,5°-11,9° sur un boîtier numérique Pentax (with a Pentax DSLR)
Plage d'ouvertures
Aperture Range
f/2,8 - f/22
9 lamelles
9 blades
Lentilles - Groupes

Elements - Groups
18 lentilles en 14 groupes
3 lentilles en verre ED (Extra Low Dispersion)

18 elements in 14 groups
3 elements with Extra Low Dispersion (ED) glass
Distance minimale de mise au point
Minimum focusing distance
1.00 m
Grossissement maximum
Magnification ratio
QuickShiftOui - Yes
Moteur AF

AF Engine
Diamètre de filtre
Filter diameter
67 mm

Weather protection

Dimensions(longueur / diamètre) (Length / diameter)
136 mm x 76,5 mm

Bouchons avant & arrière - Pare-soleil - Sac

Front and rear caps - Lenshood - Soft case
Compatible FFMode Crop ou Mode 1:1

No : crop mode only or 1:1 mode
The ★ (STAR) lenses

This zoom lens appeared on the marketplace in 2007, just like the DA ★ 16-50 mm f/2.8, of which it was the logical complement for APS-C sensor bodies.

At Pentax, the ★ (STAR) lenses represent the top of the line in terms of performance. Not only in terms of pure performance (optical quality, sharpness, homogeneity), but also in terms of manufacturing, with quality materials that offer both toughness and enhancements.

Talking of the sturdiness of the DA ★ 50-135 mm f/2.8 can bring a smile to your face, just like for the DA ★ 16-50. So, those who have owned a « problem » copy will probably have a forced laugh. But it suffered far less from SDM problems than its « little brother ». The copy used for this review never had any problems so far. And yet it has been used more or less regularly for the last 6 years. It is often recommended, when the lens has been unused for a long time, to « wake up » the SDM by manually operating the zoom and focus rings several times. For the focusing ring, remember to position the focus manually, both on the body and on the lens. This is essential to avoid forcing the mechanism.

Optical formula

The optical formula is represented in the diagram below :

DA ★ 50-135 mm f/2.8
Optical diagram of the Pentax DA ★ 50-135 mm f/2.8


As you can see, the optical formula of the DA ★ 50-135 mm f/2.8 includes 3 ED (Extra-low Dispersion) glass lenses. Their use makes it possible to design smaller (and lighter) lenses. One of the main purposes is to eliminate chromatic aberrations as much as possible by avoiding light dispersion. The corollary is that the images are theoretically sharper.

The diaphragm has 9 blades, as often in the ★ series (2). For lenses dedicated to macro, this makes the bokeh more « creamy « . For others lenses, such as this DA ★ 50-135 mm f/2.8, it makes smoother and more progressive the transitions between the different planes of a photo.

Manufacturing quality

The ★ (Star) series from Pentax is characterized, among other things, by high manufacturing quality. Of course, that’s true for this DA ★ 50-135. Its construction quality is flawless. Even after many years of loyal service, no slack will appear. If the photographer is careful, the materials « age » well. It’s hard to ask for more!

The barrel is mainly made of polycarbonate, but it is of high quality. It does not have any « economic » character. The focusing and zooming rings, covered with a rubber coating, are well designed: their handling is pleasant and easy, their width is adapted to all kinds of hands.


The SDM engine, which is 15 years old, now appears to be very outdated, not so much in terms of accuracy but rather in terms of speed of operation, by the latest Pentax products (DC, PLM, new SDM). Moreover, if the reliability problems mentioned in the test of the DA ★ 16-50 mm are here even more largely in the minority, they did exist, and also on other SDM lenses of the same period. However, as with other SDM lenses, this motorization is silent in operation.

Quick Shift

The DA ★ 50-135mm f/2.8 benefits from the « quick Shift » feature. Recall that this allows you to manually adjust or slightly modify the focus after the AF is achieved. A significant comfort in many situations. But it is necessary, for this purpose, that the handling of the focusing ring is sufficiently flexible and precise. This is the case here. Note also that, if the subject is at a distance (even slightly) lower than the minimum focusing distance, the quick-shift will not work and it will not be possible to operate the focus ring. A safety feature to avoid blurred photos by distracted photographers.


This zoom lens has an « AW » (All Weather) tropicalized construction superior to the « WR » (Weather Resistant) finish. This allows it to be used in harsh conditions: rain, snow, dust. However, this does not make it a lens that can be used underwater.


Manufacturing & Finishing : 6

Technical specifications : 10

Main Optical data

PENtaxKlub does not have a laboratory. Our tests are not measured by tools. We wish to bring a user and essentially photographic point of view. Our comments and technical note are therefore the result of a visual analysis.

Please note that for any lens, even the best one, it is always possible to obtain visual imperfections (especially with CAs), whatever the focal length and/or aperture.


Test photos

All the photos used for the tests were taken in RAW format (PEF or DNG). Unless explicitly mentioned, not developed or not retouched.

Note: For all these test images, the shooting conditions are as follows:

  • camera on a tripod, in M (manual) mode, AF assistance activated
  • remote control release (after adjusting the aperture and exposure)
  • focus on the area marked with a blue dot on the image below
focusing areafocal length 50 mmfocal length 90 mmfocal length 135 mm

Aperture Entire picture
f/2.8 (WO)
Aperture Entire picture
f/2.8 (WO)
Aperture Entire picture
f/2.8 (WO)
Chromatic Aberrations and flare

Any lens is likely to produce chromatic aberrations (CA) and flare.

CAs appear as a purple (or green) fringe, unpleasant to the eye. They form when the 3 colors of white light (Red, Green and Blue) pass through a lens, separate and do not meet in the right place to produce a sharp image.

Flare occurs in certain light conditions, such as when the sun sends its rays at an angle to the lens.

This is why we prefer to judge a lens in common and not exceptional image situations



focal length 50 mmfocal length 90 mmfocal length 135 mm
CAs and flare at 50 mm f/2.8 Detail 100 % – CAs and flare at 50 mm f/2.8
CAs and flare at 50 mm f/5.6 Detail 100 % -CAs and flare at 50 mm f/5.6
CAs and flare at 90 mm f/2.8 Detail 100 % – CAs and flare at 90 mm f/2.8
CAs and flare at 90 mm f/5.6 Detail 100 % – CAs and flare at 90 mm f/5.6
CAs and flare at 135 mm f/2.8 Detail 100 % – CAs and flare at 135 mm f/2.8
CAs and flare at 135 mm f/5.6 Detail 100 % – CAs and flare at 135 mm f/5.6

These images were taken in typical Parisian weather, which is generally cloudy and very propitious to the appearance of CAs.

Their examination, and in particular that of the 100% extracts, although taken out of the plane of sharpness, allows us to draw the following conclusions.


Concerning the CAs

They are globally weak, but not non-existent.

At 50mm, they are visible at full aperture (f/2.8) as green or red bangs depending on the orientation. Although largely weakened, they remain apparent at f/5.6 and up to f/11.

At 90mm, they are barely visible at full aperture, and almost undetectable thereafter.

At 135 mm, surprisingly, they reappear, but very slightly from f/2.8 to f/8 and disappear completely at f/11.

This overall weakness allows to correct them very easily in post-processing.

Concerning flare

The test photos did not reveal any flare at all. But of course the lens hood was mounted on the lens, which greatly reduces the risk of flare. By the way, PentaxKlub recommends the systematic use of the lens hood to limit as much as possible the appearance of flare. And incidentally, it constitutes a first protection of the front lens.


The test pictures did not reveal any vignetting. At least on a body suitable for this zoom (APS-C) and used for this test.

Some see the DA ★ 50-135mm f/2.8 ED [IF] SDM as compatible (with limitations) on full frame body (K-1 and K-1 II), especially in crop 1:1 mode. We will see later what it is.

focal length 50 mmfocal length 90 mmfocal length 135 mm
f/2.8 – 50 mm f/5.6 – 50 mm
f/8 – 50 mm f/11 – 50 mm
f/2.8 – 90mm f/5.6 – 90mm
f/8 – 90mm f/11 – 90 mm
f/2.8 – 135mm f/5.6 – 135mm
f/8 – 135mm f/11 – 135 mm

The shooting conditions were as follows :

  • shooting outside in « mixed » weather, with changing light, which explains the colorimetric variations
  • camera on tripod at a constant distance (about 4 m / 13 ft), whatever the focal length
  • remote control triggering

The distortion is relatively strong (barrel) at the shortest focal length, whatever the aperture. It almost disappears at 90 and 135 mm.


Homogeneity and sharpness of the image

The shooting conditions are the same as for the test images.

focal length 50 mmfocal length 90 mmfocal length 135 mm
Aperture Center Border
f/2.8 (WO)
Aperture Center Border
f/2.8 (WO)
Aperture Center Border
f/2.8 (WO)

Generally, the homogeneity and sharpness of the image are not a big problem with fixed focal length lenses. At least for those designed for digital photography. Provided, of course, that the photographer does not neglect his focus. Of course, there are exceptions, but they were much more frequent with the lenses of the film era which favoured the center of the image, to the detriment of the periphery.

The same is not true with zooms, for which it is much more difficult to compose an optical formula that ensures homogeneity and sharpness of the image over the entire field covered, whatever the focal length.

This Pentax DA ★ 50-135 mm f/2.8 is, at least in part, an illustration of this.

Image analysis

The examination of the images leads to the following remarks.

At 50 mm

Center : the image is only decent at f/2.8 and improves greatly afterwards, especially at f/5.6 and f/8. There is a slight drop at f/11 and a very strong drop at f/16, probably due to diffraction effects.

Border : the 2 best apertures are f/4 and f/8. We note an inexplicable and significant drop in quality at f/5.6, a fairly good image at f/11 and, to a lesser degree, at f/16.

At 90 mm.

In the center: the image is good from full aperture, improves from f/4 to f/11 (which does not mean that f/11 gives better results than f/4) before showing a slight drop at f/16.

On the border: correct at f.2.8, the image is good from f/4 to f/8 before being significantly lower at f/11 and f/16

à 135 mm

In the center: the image is good to very good at all apertures and shows a noticeable drop at f/16.

On the border : the image is good to very good from f/2.8 to f/8. It shows a slight drop at f/11, a little more accentuated at f/16.

Generally speaking, homogeneity and sharpness do not call for any particular criticism, except at the f/16 aperture which, in all cases and at all focal lengths, proves to be the least good. However, it is still usable in many situations. Classically, the best images are obtained from f/4 to f/8. This is certainly not a scoop !

Focus areafocal length 50 mmfocal length 95 mmfocal length 135 mm

Bokeh – The central blue dot represents the focus area (on the 2 « R » of the word « Charrette »)

The background is roughly located 8.50m (about 26 ft) behind the subject.

The bottle is about 1.10 m (3.3 ft) from the sensor plane.

f/2.8 f/5.6

The bottle is about 2.30 m (6.5 ft) from the sensor plane.

f/2.8 f/5.6

The bottle is about 4 m (13 ft) from the sensor plane.

f/2.8 f/5.6


Image quality (homogeneity, sharpness, distorsion) : 27

Optical quality (Aberration, flare, vignetting) : 33


With a full frame body

As we said before, some people think that this zoom is compatible, with limitations, with full frame sensors. This is true, with no limitation other than image resolution, but only if you operate in APS-C crop mode.

But, even in a 1:1 crop that is considered as usable, some vignetting still occurs. Sometimes, for example for outdoor views, it can still be corrected in post-processing. In all other cases, the vignetting produced is much too important, limiting the workable surface of the image to the central part. This is what leads us to say that, like most Pentax DA zooms, this 50-135 is not compatible with the full format (24×36), whatever the focal length and aperture. The vignetting is so important that it « eats » a large part of the image. Even in 1:1 crop it remains very visible (see images below).



K-1 II - mode "normal" - 123mm - f/9 - 1/200s - ISO 400 - -1IL
K-1 II – « normal » mode – 123 mm – f/9 – 1/200s – ISO 400 – -1EV


Here, in « normal » mode, the vignetting is too important to be tolerated.


The same subject, shot with K-1 II and 50-135 mm in crop 1:1. On a black background, the slight vignetting is obviously not visible …

K-1 II + DA* 50-135 à 135mm - ISO 400 - 1/40s - f/9 - -1IL
K-1 II + DA* 50-135 at 135 mm – ISO 400 – 1/40s – f/9 – -1EV

… while it is clearly visible on a lighter background:


avec K-1 II
K-1 II – 135 mm – f/9 – 1/125s – ISO 400 – -1EV
Let’s widen the subject!

The photo above was taken indoors: the vignetting is clearly perceptible, but corrections are possible.

Outside and with a good light, despite a wider framing, this vignetting is much less visible:


Crop 1:1 mode outside (good light)


And here are 3 images taken in « normal » mode, on K-1 mark II:

Focal length 50mm – f/5.6
At 90mm – f/5.6
At 135mm – f/5.6

And we shall conclude with an image corresponding to a 1:1 crop, extracted from the original of the last photo above (focal length 135mm). One will understand better the good reason for the 1:1 crop implemented in the K-1 and the K-1 II !

Extract in 1:1 format, from the original photo,

Price and competition

At the time of writing this new test of the Pentax DA ★ 50-135 mm f/2.8, its list price, excluding special offers, is €1,199 in France. This is a sum that very few photographers are nowadays ready to spend for a very good quality lens, certainly, but finally old.

On the new equipment market, with comparable quality, there is nothing left. Its only competitor, in the past, was the Sigma 50-150/2.8, whose production was stopped many years ago, a long time before Sigma decided to abandon the K mount.

However, it can still be found on the second hand market.

In the brand itself, at this level of quality, there is no competition. This could only come, in terms of focal lengths covered, from the sliding aperture zooms such as 18-135, 18-270, 50-200 and 55-300. And also the DA* 60-250, a quality zoom with a smaller fixed aperture (f/4) and much more expensive (1499 €). Moreover the 10mm difference between the two low focal lengths (50mm – 60mm) is quite noticeable in reality. And what about the recent DFA 70-210/4 with the same price as the DA* 50-135/2.8, but with a 20mm difference at the shortest focal length?

Unfortunately, only one of these potential competitors belongs to the « Star » series, and none of them offers a maximum aperture of f/2.8

There are rumors of a possible 50-300mm DFA zoom, also with sliding aperture, in the next months. Plausible or not? The medium term future will tell us.



The Pentax DA ★ 50-135mm f/2.8 is, overall, a zoom lens with excellent optical quality. It produces images of great precision, with faithful colorimetry. It will be used particularly in the common circumstances of life: landscape, street photography and indoor sports especially – provided you can live with its rather slow AF – , portrait. In short, a lens that is inherently quite versatile.


  • Maximum aperture f/2.8 at all focal lengths
  • Image quality
  • Overall manufacturing quality
  • Slowness of AF
  • Sometimes capricious reliability of the SDM motorization
  • Distortion
  • Price

One might think, after reading this « review », that this lens is to be avoided. Having owned one for nearly 6 years (and without the slightest incident!), I think that would be a mistake. Used in good light conditions, the DA ★ 50-135mm f/2.8 will in most cases be satisfying for its owner. As far as AF is concerned, any photographer with any experience will be careful to pre-focus before actually shooting. Knowing how to visually appreciate the real distance of the subject is then an important asset.


Handling 10 Uncompromising and well thought-out: the DA 50-135 is easy to use
Manufacturing & Finishing 6 Manufactoring and finishing are perfect, even 13 years after the market launch
Technical specifications 10 Still without reproach: the quick-shift is a very useful feature..
Image quality (homogeneity, sharpness, distortion) 27 Sharpness is excellent, especially in the center of the image, but the borders are recessed. The distortion is enormous at the shortest focal lengths.
Optical quality (Aberration, flare, vignetting) 33 Correcting CAs is relatively easy. Flare can be avoided. Vignetting can be corrected as well, but it is too important at short focal lengths and larger apertures.
Overall rating 86/100


(1) The SDM motorization has been implemented since 2007. The first camera to be compatible with this motorization was the K10D, at the price of an update of its firmware to version 1.30.

(2) The recent DA★ and D FA★ all benefit from 9 diaphragm blades, some FA★ as well. But other FA★, F★ and A★ have « only » 8 blades.



The photos in the gallery may have been developed.

(Note: All images below were taken with a K-3 II body and the DA* 50-135 mm/2.8)

Leaves – f/8 – 1/50s – ISO 100 at 50 mm
Fall colors – f/8 – 1/50s – ISO 100 at 80 mm
A street in Paris – f/10 – 1/200s – ISO 320 at 85 mm
New (but sad) 2 rooms apartment in Paris – f/6.3 – 1/400s – ISO 320 at 75 mm
The distant flight of a heron – f/9 – 1/500s – ISO 320 at 135 mm
Reflections on the Japy Gymnasium in Paris – f/7.1 – 1/1000s – ISO 800 at 50 mm
Skater of the Place de la République – f/10 – 1/1250s – ISO 2500 at 58 mm
Curfew – f/8 – 1/320s – ISO 320 at 50 mm

Credits : © Micaz – All these photos are the property of the author (unless otherwise specified) – Click to enlarge

Translation to english by Micaz. Sorry for the flaws.