Shootout Again! DA* 16-50 Vs SIGMA 18-50/2.8

Here is a very recently published shootout test for the above two lenses:-

http://forum.pentaxfans.net/showthread.php?t=54131

(The report in Traditional Chinese, you can use Babelfish to translate)

Nonetheless, since Babelfish is not something one can fully understand :-D, I summarise the author's findings as follows (you may wish to read in conjunction with the full report with all those testing sample pictures posted):-

1. Purple fringing of the DA* is more obvious than the Sigma at the widest focal settings, for apertures from f/2.8 to f/8, i.e., at 16mm Vs 18mm respectively. The author compares the image corners.. ;

2. Exposures (i.e., for the image brightness) and colour/tone responses are more or less the same as tested at 50mm;

3. Resolution of the Sigma throughout the same aperture range (f/2.8 to f/8) wins the Pentax clearly, at the widest focals as compared. My comment is that this comparison may not be totally fair as the magnification of the Sigma at 18mm is slightly larger. As such if the same crops of the same image scene are compared, the larger magnification one will have the slight advantage. However, the difference seems to be so obvious that the Pentax should really have (much) less resolution. Also, the tester also tested at 34mm/35mm to verify his results on another day and yet again he found that the Sigma is still having better resolution;

4. Focusing accuracy test: The Pentax DA* back focused whilst the Sigma focused flawlessly on the same K10D!(?) The author remarks that this confirms the reported (back) focusing problem of the DA* lens, when SDM is used. He further writes that the focusing error could be the true culprit for the decreased and lower resolution as found. I think he is right for that suggested point as focusing accuracy is very important to keep the (high) effective resolution;

5. Distortion levels of both lenses are more or less the same and both are quite obvious. My comments are: I can see from the test images that the test chart/target are not shot "perfectly" on an optical bench for perfect alignment nor the target is perfectly flat. However, this is understoodable for what a non-professional measurebator could do with the limited resources he has. Still, the test shots can be treated as some kind of basic reference, IMHO;

6. The author is astonished at the high performance/cost to price ratio of the Sigma but however rather disappointed with the Pentax DA Star, which is expensive but yet found to be inferior and lose the shootout for almost all aspects under test;

Well, after reading this test and all the results, I feel rather disappointed (again). The DA* Star is again something let Pentaxians very down in general. It has focusing issue as verified, which has been reported over and over again since launched. The true cause can be either a design flaw, no matter hardware and/or software wise or a quality control issue. The DA* optically does not live up to the standard as supposed and expected. Actually, it has more obvious purple fringing, lower resolution, obvious distortion and so on - and the worse is that it cannot even win but just lose to the Sigma which is being sold at a price less than half of the DA Star.

My impression is that the DA Star is just something Pentax created to hurt seriously their long established reputation of their only true strong point, i.e., excellent optics, especially for the Star series, which should be their top-of-the-line, most luxury glass with the best possible optical quality and performance on the Earth, but still being sold at attractive and reasonable price levels - which all these favourable factors are true and valid for the old film FA* and F* or even A* lenses. But now that it looks rather sad and disappointed for those digital DA* "Star" are found to be performing just like some kinds of rebadged Tokinas which are actually being sold much cheaper. Still, the Pentax Digital "Star" are yet marketed with a "Star" price but lack the true quality and real performance which they should have (or at least as expected or supposed to be), as reported by many of the new users for what have been tested and verified repeatedly from many of the recent reports. (Not even to mention the unique optical characters which each of the old *true* Pentax Star lenses had - Sad. Really..)

Afterall, I believe that the consumers are brilliant, overall speaking. Reputations, no matter good or bad, are built over time and nothing can be hidden or cheated. So, if the DA* really don't perform, I'm afraid that Pentax is really endangering their brand name and just spoil their long-established good name of the Star and when the end of the Star legend comes, their old real fans must be upset (mostly).