The exact features were unknown apart from rumours until this press release:
Two new smc PENTAX-DA ( DA Star ) Zoom Lenses
Both lenses are designed by a collaboration between Pentax and Tokina, with the Pentax adding SDM (supersonic drive motor for quiet AF) and WS (weather sealing) to the design. The latter features (and the suffering of my zoom kit during travel) made me decide they could provide for a two lens travel setup, so I ordered them from Tekade.de. The lenses have been arriving at their owners for a week or two now, but I seem to be among the first forum regulars to have received them. My report does not include brick wall nor other test shots. It shows my observations from a users point-of-view. Images will follow, but not full size...
I finally received my two DA*s Saturday and I tried them out immediately. The DA*50-135/2.8 is optically clearly the better one of the two. From the first shots I was clear to me that zooming in on the LCD screen the DA*50-135 delivered crisp sharp images similar to what I get from the best of my glass. I'm sure there will be pixel peeping differences, but not of the magnitude that I would care... The DA*16-50 was a bit less, but still I found it better than the average results of the DA16-45.
The weight of the lenses is considerable, but they balance well on the K10D with grip. Mounting them on the camera feels different because you feel the weather sealing slightly damping the rotation. I did miss a firm grip on the lenses while mounting them, with the wide focus ring and the wide zoom ring there's not much fixed barrel to grip onto. I still regret Pentax abandoning the little ball for gripping onto... But this is more a habit than anything else. Once I get used to holding the lenses further from the mount when (dis)mounting I'm sure it'll be as easy as other lenses.
The size of the DA*16-50 is slightly larger than the DA16-45. The DA*50-135 is about 3/4 of the Sigma EX70-200/2.8 (pre-DG version, but I think they are all the same), but with the hood on both the difference is only about 2cm.
The focus ring obviously doesn't rotate when AF is working (same with SDM or traditional AF), and Quick Shift Focus sets in from the moment you turn it yourself allowing immediate manual focus tuning. This works great providing much more grip on the lens, but if you're used to holding the focus ring without it affecting focus like on the Sigma EX lenses some getting used to is required. The focus ring doesn't stop at the extremes of the focus range, as you can turn it further though you feel additional friction. Makes for steadier handling, similar to FA* standards.
The zoom ring is considerably different between the two, with the DA*16-50 feeling much more rigid than the DA*50-135. The latter having internal zoom makes the difference I guess, since the DA*16-50 extends when zooming in, which means two weather sealed barrels are pushed out of the construction, the first one rotating, the second not.
SDM... By my observation (not measurement!) it is NOT significantly faster than regular AF. Strange thing is that when I looked at the movement of the distance scale when focusing, I didn't notice any difference in speed, but I did when looking through the viewfinder. The lens seemed to slide into focus much faster... Guess less noise and the sliding into focus makes a big difference in perception. Also you don't feel the lens rotate, which was the case with traditional AF ever so slightly. Not a faster but a much nicer experience nevertheless.
Makes me think the actual difference in AF speed between Pentax and the other quieter brands isn't so much after all, more perception than anything else?
Esp the DA*50-135/2.8 doesn't seem a fast focuser. Hunting up and down takes a while. The Sigma EX70-200/2.8 is much faster. On the other hand, the Sigma only covers from 1.8m to infinity, and the DA* from 1m to infinity with the range between 1m and 2m covering slightly over half the entire movement of the focus ring. Taking that into account, focus speed on both should be around the same, hunting time doesn't mean a thing when focus range isn't taken into account.
SDM is retained when using a TC with powerzoom contacts. Though SDM AF does seem to suffer more easily from adding a TC. I mounted the Tamron 1.4x without problems on the DA*50-135. However this combo doesn't seem to lock focus all the time. The lens slides into focus that's visually correct, but the focus lock doesn't engage. Since I use the AF button to AF and my shutter release is AF independent I guess I could live with that, but others may find that a problem.
Neither DA* will mount onto the Sigma EX2x TC however because of its protruding front element.
With a polarizer the DA*16-50 focuses no problemo! Not like the DA16-45 which sometimes refuses to focus with a polarizer, esp at 16mm. Haven't tried the DA*50-135 yet, but it will inherit the polarizer of the DA16-45.
The hoods on both lenses are of better quality than the ones on the DA16-45. Both have the polarizer door at the bottom, which is inserted nice and tightly. The front lens cap has a center pinch to remove it, which makes for practical usage with a mounted hood.
Both lenses come in the classic Pentax pouch. the rear caps have the rim to protect the contacts. Nothing different to what we know there...
The DA*16-50/2.8 seems to deliver images similar to the DA16-45/4. Not in terms of sharpness of so, but in terms of exposure. I guess the 16mm wide angle is mostly responsible for that. I fear the threads about underexposure with this lens will be coming soon... Though those who came to appreciate the DA16-45/4 know this is a very relative thing, some Ev compensation at the wide end may be required in certain situations. I didn't experience this with the DA*50-135, but that's normal since telephoto scenes generally have less DR than ultra wide angle ones. Anyway, it's not a problem for me, but I guess it should be mentioned for those who might consider it so...
Closest focus distance is very workable on both, though the DA*50-135 at 1m is at the limit. It having a slightly shorter minimum focus would have been handy. The 30cm of the DA*16-50 feels much less than 30cm.
Overall both lenses are very much to my satisfaction, and I think both with serve me well for the purpose I got them, i.e. travel to the wetter and/or more dusty places on our planet.
I think this about covers all aspects that I considered. I'll post an update should I think of anything else.
hth, Wim
