My apology for the delay in posting second part of the review. My working hours have been extremely irregular this past couple of weeks that any serious and productive blogging is virtually impossible. Anyway, here it is now, the second part of the smc Pentax D FA Macro 100mm F2.8 WR review.
I’ve added the word “user” in the title to reflect the spirit of this series of write ups, which is to share my experience in using the lens and hopefully there will be useful information shared in the process.
This is the second part of a planned three-part series. The first part, here, serves as a quick glance into Pentax’s promise of nice bokeh, which I think is delivered quite nicely, as nice a bokeh you can expect from a f/2.8 100mm macro lens.
Fly macro
Prior to buying this lens, I had actually been looking at the old smc Pentax D FA 100mm lens and Sigma 105mm f/2.8 EX DG Macro.
I decided to go for the D FA 100mm WR purely on the assumption that “since this is new, it must have been manufactured to perform better than the older one.”
Both the Pentax 100mm Macro and the Sigma 105mm Macro are over four years old and although lens ages much slower than a camera body — some lens remain desirable many years after their release like the Pentax Limited lenses — I reckon that newer a lens should always be better, or at least try to be better than its predecessors, hence the decision to go for the D FA 100mm WR.
Further more, it’s weather resistant — a logical companion for the K-7.
Specification
smc Pentax D FA 100mm f/2.8 Macro WR
| Focal length | 100mm |
|---|---|
| 35mm equivalent | 153mm |
| Maximum aperture | f/2.8 |
| Minimum aperture | f/32 |
| Number of diaphgram blades | 8 |
| Angle of view | 16 degrees (with Pentax DSLR) |
| 24.5 degrees (with Pentax film SLR) | |
| Construction | 9 elements / 8 groups |
| Focusing range | 30.3cm - infinity |
| Magnification | 1:1 (1x) |
| Filter size | 49mm |
| Mount | Pentax KAF |
| Weight | 340g |
| Dimensions (Length x Diameter) | 80.5mm x 65mm |
| In the box | Lens, lenshood case, lens cap |
| Special Features | Weather-resistant, rounded diaphram blades, "Quick shift" focus system, super protect lens coating |
[Source: Pentax]
On the camera
The following YouTube clip is how the lens looks like on the K-7. The red ring on the base of the lens is the WR seal. The clip is without a narration though; I have got a strange Borneoan accent which I rather keep out of the realm of YouTube 
As can be seen from the YouTube video, the lens is quite small even on the K-7′s compact body. The also lens extends out as the focusing distance gets narrower; thankfully the hood helps to balance out the “imbalances” and hide the lens protrusion. Or else, things could look a bit uncool.
There’s nothing to control on the lens except for the focusing ring. No switch, no aperture ring and so on; just the focusing ring, so it’s pretty much a mount-and-shoot lens.
Apart from shooting macro and close-up, the Pentax 100mm F2.8 Macro WR is also useful for a medium telephoto photography and capable of producing sharp results.
Autofocus is quick in the normal range but the same cannot be said when focusing on its minimum range. It tends to hunt at macro range and a focus limiter would have been useful but just like its predecessor, this feature is missing.
The only consolation is the Quick Shift focusing system which allows a user to fine tune the focus by tweaking the focusing ring.
[Part III: Image Quality and Conclusion...]
