This Old Lens: Pentax 100mm f/2.8 WR Macro Lens Review – Another Look

I have written about this lens before. Several times in fact. There is that initial review and other posts like the favorite Pentax lens post I wrote for KEH and a recent agnostic top ten lens post. The moment I decided to step back into the Pentax mount I knew this was a lens that would not be far behind it. For the why I will repurpose and update the list from the earliest post and then follow up why I think this lens is special as compared to other lens mount options I passed on.

• WR or water resistant. In the first post I was speaking theoretically, but I can now say with confidence from experience that this is a stout weather sealed lens. It has been taken out and drenched in harsh conditions and has not ever failed me.

• Metal construction with engraved text. My prior lenses were well built, but none went so far as to have an all metal build.
• Sample images impressed.
• Focal length makes for a fantastic portrait lens. I have purchased the Pentax 77mm f/1.8 in the past, but based on experience I will use this as a portrait lens this time around. At a 150mm full frame equivalent on crop bodies it also makes an especially impressive portrait lens. And since it is a macro lens you do not have the same distance restrictions most long, relatively fast primes have.

I compared this lens to a couple of lenses last time. One mount is no longer relevant, the Samsung 60mm macro, and I will add another lens from a system that I currently use.

Sony FE 90mm f/2.8 Macro G OSS

Olympus M.Zuiko Digital ED 60mm f/2.8 Macro

Pentax 100mm f/2.8 strong points.

• Size. The other full frame option, the Sony, is massive compared to the Pentax. The size is comparable to the Olympus, but the Olympus is longer even though that lens is built for a MFT sensor. Pretty impressive packaging.
• Full frame compatible. The Pentax lens does well with APS-C bodies, as I first used it before the K-1 was announced, but I feel the focal length is a better fit for full frame.
• Price. At less than $400 it is a bargain when compared to the over $1,000 Sony. The Olympus is priced similarly, but the advantage goes to the Pentax for me since it is full frame.

Pentax 100mm f/2.8 shortcomings.

• No focus limiter switch. Understandable, but with AF macros I have owned I tended to switch to MF whenever I wanted to take a macro shot and here that is as simple as flicking the little lever on the front of a Pentax camera. Plus I rather like the all of a piece retro-ish metal construction with no switches aesthetic (I know, nothing to do with creating images but it is a factor for me nonetheless.) so it is a trade off I accept easily. Here is a series of 4 shots taken from the same position back to back from far to near.

• Sony has IS in the lens, in addition to Sony IBIS on most cameras, but like the Olympus this lens relies on the camera’s in body IS. This works just fine for me especially considering the smaller price, size, and weight this allows.

It ticks off all of my expectation boxes. I recently saved a bit more on this go around by winning an eBay bid and will update further once it arrives. (Hass arrived and fortunately it is a positive eBay experience.) Here is an ongoing gallery, that will include recent images, and below are some samples from prior experience with this lens.