Originally posted by Dartmoor Dave Better than the K 24mm/2.8, I'd say. I used to own the K version and was entirely underwhelmed by it in comparison against the Takumar 24mm/3.5. Those shots with your A 24mm look far better than I remember from the K, with much more vivid colour rendering and much nicer contrast.
EDIT: I've just looked in the lens reviews and see that the K and A are optically the same. But looking at your shots and the samples in the review section, I'm guessing that the coatings must have changed significantly because the rendering looks quite different to me.
The coatings did change significantly. No way the K version could do blues like this, this is the "A" trademark - I've had a few A lenses and still have the A 70-210mm and I can tell this is very typical "A" rendering, except with even more contrast and saturation (possibly multi-coating of all the sides of all elements? That is the not-so-secret-weapon of the Ricoh GR's beautifully saturated color and contrast).
In fairness, my post-processing also changed since I've had the K, but still, there is a difference.
In regards to the importance of coatings, I found this recent review of the Tokina 35mm f/2.8 Macro quite interesting...
Quick Review: Tokina 35mm 2.8 Macro AT-X Pro DX - phillipreeve.net followed by the Pentax Limited 35mm f2.8 Macro review...
HD Pentax DA 35mm f2.8 Macro LTD: a quick report. - phillipreeve.net
In short (so you don't have to read it), it is horrible against bright light - flare, loss of contrast, aberrations, you name it. Something anyone knows to be a point where Pentax excels.
This quote tells it all: "It has good contrast, and the Pentax version has gone from disastrous flare in the Tokina to superb performance. I’m quite amazed there can be so much improvement without changing the optical layout."
So yeah, coatings make or break a lens and are as important as the glass itself
By the way, the pictures above have a couple tone curves that add some saturation and contrast, plus a small amount of contrast (+5 I think). The saturation was not increased at all, except for those curves that I've basically been using for other lenses, except for other lenses I do crank up the saturation just a bit...