The best lenses for Pentax K-3: Recommended wide angle, telephoto and standard lenses

Introduction

On the Pentax K-3 the best corrected wide-angle in our database is the latest HD version of the ultra-compact DA 21mm f3.2 AL Limited. This highly portable ‘pancake’ lens with its high-grade aluminum outer and engraved markings only weighs 4.2 ounces (134g) and measures just 1.0” (25mm) in length. In second place is the now discontinued smc version, which we’re showing for reference. It has the same 11P-Mpix peak sharpness but the HD coatings of the new model have reduced chromatic aberration while also improving uniformity across the field. The small increase in price seems justified, but if you already have the smc version it’s still a great choice.

Pentax HD DA 21mm F3.2 AL Limited	700	18	11
Pentax smc DA 21mm F3.2 AL Limited	650	16	11
Pentax smc DA 12-24mm F4.0 ED AL (IF)	700	15	10
Pentax smc PENTAX DA 14mm F2.8	575	15	8
Pentax smc DA 15mm F4 ED AL Limited	510	14	9
Pentax HD DA 15mm F4 ED AL Limited	700	14	8
Tamron SP 10-24MM F/3.5-4.5 Di II LD Aspherical IF Pentax	499	13	8
Sigma 8-16mm F4.5-5.6 DC HSM Pentax	699	13	8

We’ve also included zoom models in the rankings this time, as we’ve still some lenses to add to the sample. From the rankings, it’s clear that the Pentax smc DA 12-24mm f4.0 ED AL while not great on the K-5 is a very good performer on the 24-Mpix K-3 sans AA filter, especially given the relatively accessible price ($700). It’s sharper at the wider end like most zooms of this type and, with a peak sharpness of 10P-Mpix, is comparable in sharpness with the firm’s primes of the same focal length, at least at the wider end.

As an equivalent to a 21mm (on a 35mm FF) the smc DA 14mm f2.8 ED (IF) resides in third place of current models. With a 77mm filter thread and measuring 3.3” (83.5mm) in length it’s a large lens given it was designed specifically for APS-C, but central sharpness is high at f4.0 even if the corners are some way behind. It’s also well corrected for vignetting and distortion, though lateral chromatic aberration is higher than expected.

We also like the 15mm f4 ED Limited for its small size and build quality, though the new HD model’s $700 is quite a jump over its predecessor’s selling price of $510. It has lower distortion and vignetting than the 14mm and it has similar optical performance from f4 onwards, though the corners aren’t quite as sharp at f8-f11.

Sigma’s new full-frame 35mm f1.4 DG HSM is also available with a Pentax K mount and it comes as little surprise to see it perform well on the Pentax K-3. Even though it’s the best performing model in this category it doesn’t exhibit the quite the same performance as we’ve witnessed on the Nikon D7100.

Sigma 35mm F1.4 DG HSM A Pentax	899	27	16
Pentax smc DA 35mm F2.8 Macro Limited	700	22	13
Pentax HD DA 35mm F2.8 Macro Limited	750	22	13
Pentax smc DA 35mm F2.4 AL	220	22	11
Sigma 17-50mm F2.8 EX DC HSM Pentax	669	21	13
Pentax smc DA 40mm f2.8 XS	250	20	10
Pentax HD DA 40mm F2.8 Limited	550	19	9
Pentax smc PENTAX DA 16-45mm F4 ED AL	335	18	11
Pentax smc DA 40mm F2.8 Limited	360	18	9
Pentax smc PENTAX DA Star 16-50mm F2.8 ED AL (IF) SDM	736	15	10
Tamron SP AF 28-75mm F/2.8 XR Di LD Aspherical [IF] Pentax	499	15	9
Pentax smc PENTAX DA 18-55mm F3.5-5.6 AL II	125	15	7

On that camera the Sigma has excellent sharpness across the field at maximum aperture through to f4, with only very slight drop in the corners. And, stopped down to f5.6, sharpness extends right the way to the corners. However, that’s not the case with the Pentax combination. The centers are sharp but the periphery is someway behind. Even at f8 the corners are still very slightly behind, and at f11 diffraction lowers sharpness significantly. In fact, it performs very similarly to the Sony mount version on the SLT-A77 – a camera with an AA filter as well as a semi-silvered (SLT) mirror in the light path. Intriguingly all three cameras have related sensors. Nevertheless, the Sigma is a good performer and it’s competitively priced, given the high-speed f1.4 maximum aperture.

In joint second place in this category are the smc and HD versions of the DA 35mm f2.8 Macro Limited, which isn’t surprising given the reputation. With the same DxOMark score, making it technically joint second, is the modestly priced  $220 smc DA 35mm f2.4 AL. It’s neither a macro (the DA Limited can go to 1:1) or as well made (it doesn’t even have any distance markings, and the build is a little low rent), but it’s a good performer optically. This lens has good uniformity even if it can’t match the sharpness of the DA 35mm f2.8 Macro Limited model till f4. The Sigma may be the sharpest overall, but if you’re unsure about the field of view (it’s one of the most difficult to master) then the Pentax 35mm f2.4 is a good first choice.

The highly regarded smc DA* 55mm f1.4 is the equivalent to a 85mm on the Pentax K-3 and, even as the most expensive listed, it’s not really surprising to see this ultrasonic-type (SDM) equipped AF lens sit at the top of the moderate telephoto rankings. At $249 the smc D 50mm f1.8 in second place looks promising in terms of optical quality but it lacks some of the refined features of the DA* 55mm f1.4 including the sonic AF motor, weatherproofing, and the nano-tech Aero Bright coating.

Pentax smc DA Star 55mm F1.4 SDM	640	27	11
Pentax smc DA 50mm f1.8	249	25	12
Pentax smc DA 70mm F2.4 Limited	545	22	11
Pentax smc D FA MACRO 100mm F2.8 WR	589	22	10
Pentax smc PENTAX D FA 50mm F2.8 Macro	444	21	12
Pentax smc FA 50mm F1.4	450	21	11
Tamron SP AF 28-75mm F/2.8 XR Di LD Aspherical [IF] Pentax	499	15	9

Sharpness at f1.4 isn’t high, but depending on your point of view, that’s probably a good thing for a portrait lens. Center sharpness is good at f1.8, better than the smc DA 50mm 1.8, and is slightly better throughout the aperture range, with the corners on both being a far way behind. Best uniformity is achieved at f2.8, though corners can’t quite match the centers for sharpness, which is true for both models. Despite the higher peak sharpness of the DA 50mm f1.8, the DA* model has the better overall performance.

In third place is the diminutive smc DA 70mm f2.4 Limited. It’s the equivalent to a 105mm but the compact ‘pancake’ design is highly attractive, measuring just 1.0” (25mm) in length and weighing 4.6 oz (147g). It’s not bitingly sharp at maximum aperture but it does have good sharpness centrally. Sharpness and uniformity improve on stopping down, as you might expect, where at f4 the corners are almost up to the center. The corners start falling behind again though at f5.6. However, corner sharpness isn’t really a big issue for most portrait lenses.

The only zoom in this category we’ve tested is the full-frame Tamron SP AF 28-75mm f2.8 XR Di LD Aspherical (IF). It’s great value and has very good image quality, at least centrally, even at the longer end from f4 onwards. Vignetting, distortion and chromatic aberration are all low, too.

Pentax users won’t be surprised to learn the smc DA* 300mm and 200mm lenses head this group. They are two very good performers with very low distortion, vignetting and well-controlled lateral chromatic aberration. Despite the longer focal length the 300mm has better uniformity that the 200mm and it’s sharper at maximum aperture (albeit a stop slower at f4 to start with). The 200mm really needs to be stopped down a stop, as sharpness at the initial aperture is a little disappointing. Center sharpness is good at f4 but optimum performance is not achieved till f5.6-8.

Pentax smc DA Star 300mm F4 ED (IF) SDM	1400	17	9
Pentax smc DA Star 200mm F2.8 ED (IF) SDM	1200	17	8
Pentax smc PENTAX DA 55-300mm F4-5.8 ED	475	14	7
Pentax smc Pentax DA 18-250mm F3.5-6.3 ED AL [IF]	499	13	8
Sigma 18-200mm F3.5-6.3 II DC OS HSM Pentax	349	13	7
Pentax smc DA 18-270mm F3.5-6.3 ED SDM	749	13	7
Pentax smc PENTAX DA 50-200mm F4-5.6 ED	261	12	6
Tamron AF18-200mm F/3.5-6.3 XR Di-II LD ASPHERICAL (IF) MACRO Pentax	645	9	5

In third place is the smc DA 55-300mm f4.5-5.8 ED, a modestly priced zoom the equivalent to an 85-460mm. It might lack the sonic-type motors of the 200mm and 300mm but what it lacks in features it more than makes up for in image quality. Unlike most lenses of this type, which are sharper at the shorter end of the zoom range, this lens performs best at 300mm. And, it has very good sharpness wide-open. Admittedly that’s a slow f5.8 at 300mm and it’s not nearly so good at 200mm (unless stopped down to f8) either, but performance starts to pick up again at 100mm at wider apertures. It has a rather complex sharpness profile, however at $475 it offers far more flexibility and is a good choice where a long telephoto might only be used occasionally.

We’re working hard on expanding the coverage of Pentax lenses, but we’re interested to know if there are certain models that you would like to see reviewed first. Please leave your recommendations in the comments section below.