理光宾得更新Limited定焦系列，很多同学都认为HD系列是SMC系列的马甲版。无意间在Pentaxforum看到一篇对比评测，摘抄了几个关键部分发上来分享。主要的改变：1.外观；2.镀膜；3.改为圆形光圈叶片。
All the Pentax DA series Limited prime lenses exhibit pleasing bokeh overall. The HD variants theoretically should have the smoothest bokeh thanks to their rounded aperture blades, but this is only visibly the case for the 40 mm lens, in our opinion. 
所有的Pentax DA Limited系列镜头都展示出令人满意的焦外。由于采用了圆形光圈叶片，HD系列理论上应该有更柔顺的焦外，但我们看来，只有HD 40mm比较明显。

So, which lens series is better: the old SMC or the new HD Limiteds? It turns out that most of the changes made between these two lineups can only be compared subjectively, including the external appearance, bokeh, and star burst effects. What we can objectively conclude is that the HD lenses do a much better job of suppressing ghosting, and in harsh lighting they may produce images with more contrast. Although ghosting is never fully eliminated, in some cases it is so hard to spot with HD lenses that you won\'t need to have to apply any post-processing whatsoever to your photos.
哪个系列镜头更好：老的SMC还是新的HD Limited? 结果是两个系列大部分变化只能主观地比较，包括外观、焦外和星芒效果。我们客观的结论是，HD系列能更好的抑制鬼影，并且在严酷光线下有更高的对比度。尽管鬼影不能全部消除，在某些严酷情况下用HD镜头你将不必须对你的照片后期处理。
HD70 F5.6

DA70 F5.6

HD35 F8

DA35 F8

HD40 F4

DA40 F4

HD15 F5.6

DA15 F5.6

全家福

所以英文和图片都转自Pentaxforum
感兴趣的同学可以浏览原帖
http://www.pentaxforums.com/reviews/hd-pentax-limited-primes/introduction.html