Lens test of D FA 24-70 f/2.8 was made with a Pentax K-1 mk II - French version
A 24-70 range lens with f/2.8 aperture has become the mandatory standard zoom in the catalog. Together with the 15-30 and the 70-200, they form a trinity where any absence is considered as a fault by some experts. It is therefore natural that Ricoh Imaging proposed this D FA 24-70 f/2.8 at the end of year 2015, shortly before the release of the K-1.
Introducing the Pentax D FA 24-70 f/2.8 HD ED SDM WR
Foreword
The Pentax D FA 24-70 f/2.8 was born Tamron, there is no doubt about it. It shares with it its main characteristics such as the optical formula, the number of lenses and the « look and feel ». Nevertheless, it differs from it on a number of points. It is not a simple name change, as it could have been said :
- The lenses are of high-end Hoya origin, which is not the case with Tamron.
- The treatment of the lenses is the Pentax’s HD treatment.
- Integrated Quickshift function, specific to Pentax
- The SDM engine is an original Ricoh.
Ricoh Imaging decided to purchase the optical/design combination for reasons of time and cost savings. This way of proceeding is questionable. But if the lens is a quality one and the price remains reasonable, why not ? The Tamron’s version of the 24-70/2.8 is considered by many specialists to be one of the best in its class ! Pentax has not made a bad choice.
General information
With its weight of 0.8 kg, this D FA 24-70 f/2.8 seems a bit massive. But is it possible to do better with 17 glass lenses and an engine ? Difficult, unless you cut back on the quality of construction (as with the D FA 28-105, whose results are inferior). Users’ apprehension about the weight of the torque it will form with the K-1 (1.8 kg) can be heard. However, the K-1 and D FA 24-70 are very well balanced and the weight is not felt as much as feared.But if weight remains a preoccupation, other solutions than the traditional neck strap must be considered. Like an hand strap or a shoulder strap.
The range covered by this lens is from 24 to 70 mm in FF (36 to 107 mm on an APS-C). From 24 mm ultra angle (UGA) to small 70 mm telephoto. An optical challenge especially since its maximum aperture at f/2.8 is constant over the entire focal length. The minimum focusing distance is 0.38 m, which will allow to get close enough to the targets.
It is equipped with the Quick-Shift function, allowing to refine the focus manually, after AF memorization.
For the filters (UV, Polarizer and other ND), the diameter is 82 mm. This has an impact on the invoice when purchasing this type of accessory.
It comes with a storage bag and a petal-shaped hood. Caution, this hood is the unmodified Tamron one; it is not equipped with the trap door allowing the rotation of a polarizing filter. Even if the shape allows a manipulation of the filter, it’s a pity, because it is a lack.
Main technical data of theD FA 24-70 f/2.8
Optical formula
This formula is complex, with 17 lenses, 4 of which are aspherical. An aspherical lens is a lens whose shape is close to a sphere, but not strictly spherical. Its interest lies in the improvement of optical performance at the image’s periphery. So many elements of this type suggest 2 things:
- It is complicated to design a zoom that is at the same time UGA (with a focal length of 24 mm) and small telephoto (with a focal length of 70 mm). That’s a big gap which brings significant constraints. Especially when the aperture is constant and large (f/2.8).
- The goal is to obtain an homogeneous image over the whole surface, from the center-field to the edge-field.
Two points that should be checked during the tests.
The construction also includes 3 ED (low dispersion) glasses in order to reduce chromatic aberrations and to increase the sharpness and the rendering of the colors.
If the focus is internal, the passage from focal length 24 to 70 mm will be made by a physical extension of the zoom.
The diaphragm is composed of 9 blades. From f/2.8 to f/5.6, its shape remains relatively rounded. Beyond that, the shape is not really round anymore. It is controlled automatically from the bodu (no manual control possible via a ring).
The mount is KAF3, KAF2 compatible.
Construction quality
Its construction, based on polycarbonate, is very resistant. Since its release, many copies have been sold since about 1 out of 2 buyers of K-1 (mk I and mk II) is the owner of this zoom. The return rate is very low and is more a result of problems related to drops causing off-center or lens breakage (especially frontal).
The proposed motorization is SDM type. One will appreciate the silence during focusing. It is fast, even when tracking moving subjects. Although this is difficult to quantify without dedicated tools, it is faster than the motor of the DFA 150-450 or that of the DA★ 16-50 (for for the last one, it was quite simple). Nevertheless, it seems to me to be slower than the recent D FA★ 50 and D FA★ 85. In the meantime, the engines have really made progress.
The D FA 24-70 is Weather Resistant (WR label), which means it has seals protecting against dust and water. Although WR label is inferior to the AW label, using it in difficult environments, such as in the mountains or the sea, will not be a problem. In use and with hindsight, it can be said that weather resistant is effective. Be careful, resisting water does not mean that it’s waterproof. An underwater use must be proscribed. On the other hand, if the camera and lens inadvertently fall into the water and are retrieved immediately, they should survive (experience for some).
Construction & Finition : 6
Technical specifications : 10
Getting Started
A bad point, the D FA 24-70 f/2.8 has a plastic side that gives a mid-range appearance. This is not catastrophic since the resistance is superior to that of the DA 16-85, but it is a bit behind pure Pentax productions.
The zoom ring is wide enough to not feel any discomfort during rotation (about 70° of rotation). It seems a bit hard at first, but you quickly get used to it. The rotation movement is smooth. On the other hand, the focusing ring is not wide enough for certain types of hands. With 8 mm, some fingers that are a bit big will not be comfortable. A few more millimeters would not have been luxury. It turns « endlessly », there is no stop.
The rings are coated with a rubber-like material and have small pimples that are quite pleasant to the touch. They allow to hold the ring better and avoid slipping.
We will appreciate the latch to keep the lens in closed position. Its positioning at the top right is rather unusual. A heritage from Tamron that will help to avoid inadvertently locking/unlocking it. A help to take, but finally an ergonomics that seems more interesting to me.
The lens has a distance indicator, ranging from 0.38 m (minimum focusing distance) to infinity.
The pitch of the filter (where the lens hood is blocked), is independent of the lens block. This makes the use of polarizing or graduated filters much easier and faster. These will not rotate when zooming and focusing. Going from 24 to 70 will not require a retouch of the polarizer.
Handling : 7
Technical point of view
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 ACs), whatever the focal length and/or aperture.
Test pictures
All the photos used for the tests were taken in RAW (DNG). Unless explicitly mentioned, not developed or not retouched.
note : the focal length of 24 mm is wide. So we can see the flaps on the right and on the left.
| aperture | entire image | detail |
| f/2.8 |  |
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| f/4 |  |
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| f/5.6 |  |
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| f/8 |  |
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| f/11 |  |
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| f/16 |  |
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| aperture | entire image | detail |
| f/2.8 |  |
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| f/4 |  |
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| f/5.6 |  |
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| f/8 |  |
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| f/11 |  |
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| f/16 |  |
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| aperture | entire image | détail |
| f/2.8 |  |
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| f/4 |  |
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| f/5.6 |  |
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| f/8 |  |
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| f/11 |  |
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| f/16 |  |
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Chromatic aberration 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.
CAs are present between 24 and 50 mm and at full aperture. As soon as we close one IL, or even 2 depending on the circumstances, the CAs disappear. On the other hand, even when present, they do not cause any particular problem. To find CA , you must to look for them. Above 50 mm, the lens is not affected by the phenomenon.
In common use, the flare resistance seems very good even if it can be provoked, especially below 35 mm. The use of the hood is nevertheless recommended, both indoors and outdoors, day and night.
Vignetting
At f/2.8, there is a visible vignetting in the corners throughout the entire focal length range. Some conditions may diminish the visual effect while others, mainly clear and bright skies, will accentuate it. This vignetting fades at f/4, before disappearing at f/5.6.
Distorsions
A double phenomenon for this objective. At 24 mm, the distortion is cylinder type. Although visible to the naked eye when looking closely, it remains very low. At about 35 mm, the distortion reverses and becomes cushion type, until the end of the range. But it remains low.
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It would be embarrassing if not corrected This is possible when shooting in JPEG (activating the correction function) or in Post-Processing (when shooting in RAW). This problem is related to the nature of this lens which starts its race by being a UGA. It is almost impossible to be perfect along the whole range.
All in all, this is a good surprise for this type of zoom. It shows a quality of design and construction where aspherical lenses play a very important role.
The aperture has no influence on the distortion found.
Image Homogeneity
At f/2.8, the homogeneity between the center-field and the border-field is already good, over the whole proposed focal length range, even if the sharpness is not perfect. The user will not have any bad surprises, which is a good thing. Closing by one IL, this homogeneity becomes excellent and the rest up to f/11. Between f/11 and f/16, a softening of the image gradually sets in, before becoming ubiquitous beyond f/16. As often, the f/22 aperture is not recommended, unless necessary.
| f/2.8 center-field |
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| f/2.8 border-field |
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| f/4 center-field |
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| f/4 border-field |
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It would be annoying if it was not possible to correct either when shooting in JPEG (activating the correction function) or in Post-Processing when shooting in RAW. This problem is really related to the very nature of this lens, which starts its race by being a UGA. It is almost impossible to be perfect along the whole length.
All in all, this is a good surprise for this type of zoom. It shows a quality of design and construction where aspherical lenses play a very important role.
The aperture has no influence on the distortion found.
Bokeh
| f/2.8 – Subject to about 0.70 m | f/4 – Subject to about 0.70 m |
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| f/8 – Subject to about 0.70 m | |
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| f/2.8 – Subject to about 0.90 m | f/4 – Subject to about 0.90 m |
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| f/8 – Subject to about 0.90 m | |
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| f/2.8 – Subject to about 1.20 m | f/4 – Subject to about 1.20 m |
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| f/8 – Subject to about 1.20 m | |
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At 24 mm and full aperture, the bokeh is illusory as long as you are far enough from the target. In the test shots, one can clearly distinguish the building that is about fifteen meters behind the bottle. The details are present. Some users will be disappointed to see that at f/2.8, the background is so present. It is essentially related to this low focal length of UGA type and the distance of the target. As soon as you get close to it, the feeling changes… a little.
From about 40 mm, the bokeh becomes more pleasant to become very interesting after 60 mm. At 70 mm, it is excellent for a zoom. The transitions are smooth. Even at f/5.6, the background blur remains apparent.
Image quality (homogeneity, sharpness, distorsion) : 32
Optical quality (Aberration, flare, vignetting) : 31
With an APS-C body
Although intended for Full Format, this lens is usable on an APS-C. It will offer a different focal field, ranging from 36 to 107 mm. ACs are just as present, as is distortion. On the other hand, vignetting is no longer visible at f/2.8, which is normal, as the optical frame of the APS-C is smaller. The homogeneity at f/2.8 is also improving, for the same reason. The bokeh at f/2.8 appears closer to that offered at f/4 on an FF.
D FA 24-70 : Price and Competition
The DFA 24-70 f/2.8 has no external competition. A situation that is not likely to change, as Tamron and Sigma no longer (or almost no longer) produce K-mount lenses. One could evoke the possible internal competition with the D FA 28-105 f/3.5-5.6. But the range is not the same nor the aperture range. As for the optical quality, it’s lower on the latter.
As a second hand, one will find mainly the 28-75 f/2.8 from Tamron, 24-70 f/2.8 DG Macro EX and 28-70 f/2.8 EX from Sigma. There are also other older lenses, mainly manual focus lenses.
1299 €, a price that may seem excessive to buyers. But compared to what is practiced at Canon or Nikon, clearly it is not. There are some who would like to compare manufacturer’s optics to independent opticians. In this case, it will also be necessary to compare the price of Canon/Nikon/Sony lenses compared to these same independent opticians. Pentax is more expensive than its cousins produced by Tamron for other brands (difference of about 300 €). This is probably the price to pay for a smaller market and especially a lens built according to Pentax specifications and requirements.
Conclusion
This lens is easy to use in a wide variety of practices, including studio portraiture. As such, it is the ideal companion for FF buyers looking for high performance. Even if the high level of excellence is not achieved, the images produced are of high quality. It will be hard to do better. Or at a much higher price if a D FA★ 24-70 f/2.8 was ever offered. An exceptional compromise that goes in the direction of the photographer.
This is THE essential zoom that you must have with you.
| PROs | CONs |
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Note
| Construction & Finition | 6 | A good construction |
| Handling | 7 | Excellent handling despite a slightly « cheap » look
Ergonomically speaking, the focusing ring is not wide enough, which can be a problem: 1 point less |
| Technical specifications | 10 | Constant aperture at f/2.8 over the entire zoom range, tropicalized and SDM engine. Hard to do better |
| Image quality (homogeneity, sharpness, distorsion) | 32 | Barrel distortion between about 24 and 35 mm, then pincushion type up to 70 mm, but which is easily corrected
Homogeneity and correct sharpness at PO for this type of zoom, which becomes very good, even excellent, when stopping down at f/4 Very good color restitution |
| Optical quality (Aberration, flare, vignetting) | 31 | Slightly low AC resistance at full aperture and in the 24-35mm focal length range, the « weakest » range of this zoom lens. |
| Overall rating | 86/100 | |
Gallery
Click on photos to enlarge
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Photo credits : © fyve – The pictures are the property of the author (unless specified) – Click to enlarge