Gary Wolstenholme reviews the weather sealed Pentax-D 100mm f/2.8 Macro WR lens.
Posted: 20/02/2014 - 10:40
Handling and Features
Performance
Verdict
Specification
This macro optic provides an angle of view equivalent to a 150mm on a 35mm format camera, when mounted on a Pentax Digital SLR. It sports a fast f/2.8 maximum aperture, life size magnification at its closest focusing distance, weather resistant construction and costs around £515.
Pentax-D FA Macro 100mm f/2.8 WR Handling and Features
The build quality of this lens is excellent thanks to the aluminium weather sealed lens barrel and metal lens mount. In fact due to the high quality construction and design, you'd be forgiven for mistaking this lens for one of Pentax's premium 'Limited' lenses. The weight of this lens is fairly typical for its type, at around 340g and it balances well with the Pentax K-5 IIs body used for testing.
Focusing isn't performed internally, so the lens barrel extends by a couple of inches during focusing, although the filter thread does not rotate. This makes it perfect for use with polarising and graduated filters. A hood is supplied with the lens that attaches to the front of the lens via a bayonet fitting although this doesn't move as the lens is focused. This is important as it would shade your subject when focusing at close distances if it did.
The manual focusing ring rotates during auto-focus although it is well enough out of the way to avoid catching your fingers with it accidentally. Manual focusing action is smooth and well damped , which makes applying manual focus adjustments a pleasure. The Pentax 'Quick Shift' focusing system has been implemented on this lens, which means manual adjustments can be applied once the lens has focused automatically. Auto focus is screw-driven, so it generates more noise than newer silent focusing lenses do. The minimum focus distance of 30.3cm is typical for a lens of this type and provides enough working distance to prevent shading your subject with the lens. Focusing is reasonably quick for a macro lens at normal distances, although a focus limiter may have help speed up focusing on those occasions that the camera struggles to lock onto a subject easily.
Pentax-D FA Macro 100mm f/2.8 WR Performance
Sharpness is already excellent in the centre of the frame and good towards the edges of the image at f/2.8 and stopping down as far as f/5.6 improves performance further. Here sharpness is outstanding in the centre of the frame and excellent towards the edges.
Pentax Pentax-D FA Macro 100mm f/2.8 WR MTF Charts
How to read our MTF 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 and sharpness 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-5 IIs using Imatest.
Chromatic aberrations are extremely well controlled, barely exceeding 0.25 pixel widths. This low level of fringing will be difficult to spot, even in harsh crops, or large prints.
Pentax Pentax-D FA Macro 100mm f/2.8 WR Chromatic Aberration Charts
How to read our CA charts
Chromatic aberration (CA) 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 minimize the problem, hence they usually cost more.
For this review, the lens was tested on a Pentax K-5 IIs using Imatest.
Falloff of illumination is also well controlled for a lens of this maximum aperture. At f/2.8 the corners of the frame are only 0.71 stops darker than the image centre and visually uniform illumination is achieved with the lens stopped down to f/5.6 or beyond.
Distortion is virtually negligible. Imatest was only able to detect 0.07% pincushion distortion, which is an extremely low level and should not require correction, even by the most discerning photographers.
During testing, this lens proved itself very resistant to flare and contrast levels are retained well, even when shooting into the light. The hood also does an excellent job of shading the lens from extraneous light that may cause issues.
Pentax Pentax-D FA Macro 100mm f/2.8 WR Sample Photos
Value For Money
Being priced at around £515, this lens is more expensive than offerings from third party manufacturers, but this is acceptable given how well the lens performs and how good the build quality is.
Sigma offer a 105mm f/2.8 macro lens, which costs around £380 in Pentax fit and Tamron also offer a 90mm f/2.8 lens, for around £325. The budget conscious amongst us may consider these as good alternatives, especially if weather resistance, or extra-sturdy build aren't high priorities.
Pentax-D FA Macro 100mm f/2.8 WR Verdict
As far as lenses go, this one is a top notch performer. It's sharp from maximum aperture, displays very little fringing, falloff or distortion and it is built to a very high standard. Considering all this, the price is very reasonable too, and this lens should find many a fan amongst Pentax camera owners as a result.
Pentax-D Macro 100mm f/2.8 WR Pros
- Excellent sharpness
- Weather and dust resistant construction
- Good build quality
- Low CA, distortion and falloff
- Quick shift focusing system
Pentax-D Macro 100mm f/2.8 WR Cons
- No focus limiter
Pentax Pentax-D FA Macro 100mm f/2.8 WR Specifications
| Manufacturer | Pentax | |
| General | ||
| Lens Mounts | Pentax K SMC-FA |
|
| Lens | ||
| Focal Length | 100mm | |
| Angle of View | 16 | |
| Max Aperture | f/2.8 | |
| Min Aperture | f/32 | |
| Filter Size | 49mm | |
| Stabilised | No | |
| 35mm equivalent | 150mm | |
| Internal focusing | No | |
| Maximum magnification | No Data | |
| Focusing | ||
| Min Focus | 13cm | |
| Construction | ||
| Blades | 8 | |
| Elements | 9 | |
| Groups | 8 | |
| Box Contents | ||
| Box Contents | lens caps, hood, bag | |
| Dimensions | ||
| Weight | 340g | |
| Height | 80.5mm | |
Members gallery photos using: smc PENTAX-D FA 100mm F2.8 WR Macro
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