Originally posted by Wild Mark The K28/3.5 saturates very well and generally better than most other lenses. The purplish cast is a classic Pentax signature. Many of Pentax lenses give this purplish cast - it is just a Pentax thing. You can dial down the amount of this in two ways - in camera modifications to the jpg settings or post processing.
Regarding the K30/2.8 - a task for tomorrow afternoon. Just got back from an outing and now settling in for the evening
I heard a documentary on the radio less than a year ago concerning human color perception. Remarkably, certain populations in eastern Europe were found to have insensivity to dark blues and purples (short wavelength end of the visible spectrum). This was discovered in relation to noticing that this group of people had no word that describes the color blue/purple in their language. As it turned out, none of these folks could see color in that range, thus the sky was just the sky and never described to have a color.
Frankly, the deep purplish cast described as a "Pentax" signature is mostly absent in my vision. I do see the sky as blue, though, but not harsh purples in the images described for certain Pentax lens images. That is what I call an innate corrective feature for purple or violet.
A link to the story can be found here:
https://www.businessinsider.com/what-is-blue-and-how-do-we-see-color-2015-2