Why Pentax Need a New Mount Now

Started Nov 13, 2013 | Discussions thread
audiobomber Veteran Member • Posts: 5,557
Re: 18-135mm

marike6 wrote:

audiobomber wrote:

marike6 wrote:

As it is now, if or more likely when they release a FF DSLR, the number of FF K-mount lenses is extremely small. You basically have the 31 f/1.8, 43 f/1.9 and 77 f/1.8 Limiteds, the FA 35 f/2 and 50 f/1.4 and the 50 and 100 f/2.8 Macro lenses. And of course the new DA 560 f/5.6 for a grand total of eight lenses. No wides, no zooms of any kind, only 3 Limiteds, two normal, two macro and one $7000 super telephoto.

There are a number of DA lenses that cover FF, as shown by mounting on film cameras and results posted in a thread at Pentax Forums: 35 f2.4, 50mm 1.8, 40mm 2.8, 70mm, DA*200, DA*300. I had not heard that the DA 560 is FF compatible.

I didn't that APS-C lenses like the ones you mentioned cover FF, but clearly if they are designed for a smaller APS-C image circle they are going to be dicey at best on a high resolution FF.

There's a long thread with samples at Pentax Forums, DA lenses on Full Frame: Test Shots thread. As a result of reviewing that thread, I'm going to have to revise my list. The DA 35 2.4, DA*55, DA*200 and DA*300 are fully useable on FF. The thread has not been updated with the DA 50mm, but is widely said to cover FF.

The 560 f/5.6 I thought was FF. If it's a $7000 pro grade APS-C lens that's probably a first.

The DA 560 is not listed in the test thread. and I haven't heard whether it covers FF or not.

So the lens upgrade path for APS-C DSLR users, the majority of Pentax users, is dicey at best. And for K-3 users, there are some fairly sizable holes in the APS-C lens lineup. For example they cannot keep releasing excellent bodies like the K-3 and kitting it with the 18-135. Such a lens that on 16 mp wasn't cutting it, just doesn't make sense at all on the 24 mp K-3. It puts the camera in a bad light and it needs to bet updated or discontinued.

The 18-135 is built for convenience. I'm not at all convinced that it's great optically.

The ePhotozine review, AFAIK, doesn't mention anything about the border and corner performance of the 18-135, where the lens seems to have the most trouble.

Photozone MTF test

Many of us who own the lens think the PZ tested copy was a poor performer. Here's a test shot comparing my copy at 18mm vs. the 16-45 and 15mm Ltd. I think it does well. It is certainly better than either copy of my 18-55's.


From the PopPhoto test:

In our optical bench tests, the lens produced Excellent-range SQF numbers at the tested focal lengths­—a promise of superlative sharpness and contrast. Its performance closely matched those of the comparable Canon, Nikon, and Tokina zooms, but at the aperture-range extremes, was slightly softer than the Sigma 18–125mm.

It's a superzoom, it has strengths and weaknesses. Mechanically, it feels like a pro quality lens.

It looks good in the center of the frame mainly.

As a kit superzoom, I believe there's a lot of variation in samples. I have a good one.

But it's not a bad lens I guess, but I believe the K-3 deserves better. A lot better.

I have better zooms, but they stay at home because of the 18-135's acceptable image quality, extreme convenience and weather-resistance. If I want better IQ, I use a prime.

Here are test shots I made vs. the highly praised DA 55-300mm:


135mm f8. Note the soft bokeh from the rounded blades:

18mm @ f8, nice colour and contrast. It's not shown here, but the 18-135 has extremely good flare resistance for a consumer zoom.

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 audiobomber's gear list:audiobomber's gear list
Pentax K-3 Sony a6000 Pentax K20D Pentax smc DA 15mm F4 ED AL Limited Pentax smc FA 50mm F1.4 +18 more
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