HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Review

Handling and Features
Performance
Verdict
Specification

The introduction of the new Pentax K-1 full frame camera body means that the range of lenses available had a few gaps that needed filling. As a result, a number of new 35mm-format optics have arrived, including this imposing 15-30mm. This fills an obvious and important gap in the Pentax range and it will be especially interesting to see if its performance is as impressively as its looks.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Handling and Features

This is an impressively chunky lens, with a huge bulbous front element that is what we would expect from any 15mm ultra-wide. It looks and feels very well made. 

The wide zoom ring operates smoothly and, interestingly, although the length of the optical unit changes as we zoom, the overall length of the lens does not. This is achieved with an ingenious double lens hood, integral to the lens body. The outer hood stays in a fixed position and the inner lens hood moves in and out within it. Thinking about this, it means that the lens could be supported on any surface and the moving parts will not be impeded nor will they become scratched by moving against, say, a gritty support such as the top of a wall. This double level of shielding does improve the protection for that large and potentially vulnerable front element.

Closer to the camera body is the manual focus ring, which is as smooth as the zoom action. It is ideally placed to make adjustment convenient and can be operated after AF has locked to make final tweaks to the focus point. This Quick Shift feature can be very useful, especially at closer distances. The distance scale is under a clear plastic window and gives distances in both feet and metres.

One interesting point is that the lens focuses in the opposite direction to every other Pentax lens. We have to go back to the pre-Spotmatic days of the late 1950s/early 1960s to find a Pentax lens that focuses this way round. In the days of manual focus this would have been an issue in handling as it can cause confusion in operation. However, it goes to show how AF has taken over in that I almost missed this. The number of times I would want to manually focus this lens are few and far between, so it may no longer be an issue at all.

The lens has the latest HD (High Definition) multi-coating, plus an SP (Super-Protect) coating on the front element to repel water, grease and dirt. There is no possibility of using screw-in filters. The lens cap is a large plastic push-on design that fits well and is unlikely to fall off in use.

AF is achieved with the latest version of the in-lens SDM (Supersonic Direct Motor) system, which is fast and silent. There seems to be no tendency to hunt and the system locks on every time.

Each section within this WR (Weather Resistant) lens is sealed to prevent the ingress of water and dust, so we can continue to shoot in rain and mist, or anywhere where water splashes are likely.

Optical construction is 18 elements in 13 groups. There are three Aspherical elements and three ED (Extra Low Dispersion) elements. The diaphragm has nine rounded blades, which helps to improve bokeh, the smoothness of the out of focus areas. This is a constant aperture zoom, with a bright f/2.8 maximum aperture, so it is ideal for lower light levels and for calculating flash levels manually.

Closest focusing distance is a useful 0.28m, a magnification of 0.20x. There is no filter thread. Finally, the lens weighs 1040g.

15-30mm on 35mm-format equates to 23-46mm on APS-C, and this lens can of course be used on all the previous crop sensor Pentax DSLRs. For older cameras, the AF system needs a K10D (with firmware 1.3) or later, otherwise it will be manual focus only. This means that all Pentax bodies from the last few years will be fully compatible.

Pentax lenses are always very simple in use, there generally being no special switches or mechanisms that have to be considered. This lens is no exception and is basically hassle-free. It focuses snappily, zooming and focusing actions are smooth and positive. Balance on the K-1 is excellent and the combination is easily manageable despite the weight of the combination of lens and body. For Pentax users used to APS-C sized lenses this new lens may seem large and heavy, but it works well as a unit.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Performance

In a similar way to the other new Pentax lenses released, the 15-30mm is definitely of the same design ethos. That is, very good sharpness throughout, regardless of aperture, focal length or centre or edge of the image. The degree of balance is remarkable and is clearly intended to make the most of the entire 35mm-format image area. The pattern of performance closely mimics that of the Pentax 28-105mm and 24-70mm lenses also introduced for the K-1.

MTF@15mm

How to read our charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. 

The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance. 

For this review, the lens was tested on a Pentax K-1 using Imatest.

Sharpness at 15mm is simply very good centre and edge from f/2.8 through to f/16. It falls away at f/22, as expected, but remains good even here. At 15mm we find -3.44% barrel distortion, which is good for such a wide lens. CA at the centre is almost zero and at the edges well controlled at below 2 pixels width. This is all easily corrected in software.

CA@15mm
 

How to read our charts

Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimise the problem, hence they usually cost more.

For this review, the lens was tested on a Pentax K-1 using Imatest.

20mm shows +0.154% pincushion distortion, a remarkably low figure that is close to perfectly rectilinear. That is, straight lines even at the edge of the field will remain straight. CA follows the same pattern as at 15mm, and the centre figures approach even closer to zero.

20mm sharpness is virtually identical to the wider settings and is incredibly even across the field, being consistently very good. It just drops away at the edges at f/22, but is still good.

MTF @ 20mm	CA @ 20mm

24mm gives us a figure of +1.25% pincushion distortion, still an excellent result for an ultra-wide lens, especially a zoom. CA shows the same outstanding central correction, the edges showing fringing but correctable in software.

24mm sharpness shows no sign of dropping. Whereas many zoom lenses would be becoming less and less sharp at longer focal lengths in all the new Pentax zooms this does not seem to be the case. Performance is maintained, as is the remarkable even quality across the frame. The lens at 24mm is very good at the centre and at all apertures. At the edges, the f/2.8 figure falls slightly but results are still good. The edges are very good from f/4 to f/16 and  f/22 still yields a good result.

MTF @ 24mm	CA @ 24mm

At 30mm we have +1.58% pincushion distortion, which is still a good result, although a typical 28mm prime lens would tend to show barrelling, to the handling of straight lines may look different for some shots. It's unlikely to be a problem though, more of academic interest. CA centrally is virtually banished and control at the edges actually improves. All these things can be corrected in software.

30mm sharpness still achieves the same high standard that we see at the other focal lengths and still shows the same edge to edge evenness. Centre and edge are very good from f/2.8 to f/16 and f/22 shows a drop through diffraction effects, although remaining good.

MTF @ 30mm	CA @ 30mm

Bokeh, the quality of the out of focus areas, is something that we give much more priority to than in the past. The 15-30mm shows lovely smooth transition in those areas and a very pleasant bokeh effect. There are qualities that cannot necessarily be measured in a lens, but the net effect is a very visually appealing image and this lens certainly has that, just as much as the other full frame Pentax zooms.

Flare resistance is also vital, especially in a wide angle with its relatively exposed front element. It seems that the new Pentax HD (High Definition) coating works very well indeed, and flare was not found in any of the images shot into the light.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Sample Photos

Value For Money

This lens fills a unique slot in the Pentax repertoire and is an important asset in that range. It is priced at £1499, although as always no doubt this will fall over time.

Nikon, Sony and Canon users will have to look to the Tamron 15-30mm f/2.8 SP Di VC USD lens, priced at £849. Whilst not directly relevant to a Pentax user it does show that Pentax have lost none of their propensity for releasing lenses in unusual and sometimes unique focal lengths. A look through their range of Limited lenses will reinforce this. The closest other marque lens is the Canon 16-35mm f/4 L IS USM at £682.

Although a hefty price tag at its introductory level, nonetheless the HD Pentax 15-30mm f/2.8 ED SDM WR lens delivers the goods and is an essential part of the range. For more options have a look at the Top 10 Best Pentax Lenses.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Verdict

The Pentax D FA 15-30mm f/2.8 ED SDM WR is quite simply a beautiful, sweet lens to use. It is heavy and bulky and not inexpensive, but it delivers a very high standard of performance and maintains that standard equally well at all apertures and focal lengths. From sweeping vistas to expansive interiors, a lens to aspire to.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Pros

High and very even sharpness
Smooth bokeh
Fast silent AF
Weather resistance
Well controlled CA
Excellent flare resistance
Low distortion for an ultra-wide

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Cons

Quite heavy
Expensive

FEATURES
HANDLING
PERFORMANCE
VALUE FOR MONEY
VERDICT

The Pentax D FA 15-30mm f/2.8 is a beautiful, exquisite lens to use, with lovely results.

Pentax HD PENTAX-D FA 15-30mm F2.8 ED SDM WR Specifications

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