Originally posted by creampuff Your reasoning is so flawed. Any lens being manufactured by any company of whatever maximum aperture will go through a series of QC checks. The DOF has got nothing to do with it.
This is a cheap lens targeted at the mass market at a very low price point. Everything in it's production and design is aimed at making it at a target production price.
I remember discussing with some shop keeper (LEica reseller) who was also a photographer, and he told me that after trying several faulty Voigtlander lenses he stopped retailing them. Even though Cosina make both the Zeiss and Voigtlanders, QC seems completly on another level.
I would not expect Pentax to conduct as much QC for a cheap kit lens as for a FA31ltd. Tolerances also would be on a much higher level for a kit lens. And the smaller is the DOF, the more you will see things like misaligment issues.
I don't think my reasoning is flawed on that level. And reducing the costs of acceptable QC fits in the making of a cheap lens.
Anyway, I saw in the comments on "the online photographer" another argument for a smaller max aperture. This lens is targeted to beginers, upgrading from their kit lens. You would expect them to continue shooting full auto, and in particular not paying much attention to "where" they are focusing. A little more DOF would make it more forgiving. And those users would not accuse their lens for being "soft" while in fact they where focusing on the tip of the nose instead of the eye while the lens is fully opened.