One other thought on the 23mm, is the center filter. I used the CF on the 28mm (still greatly wish I had that lens since I upgraded to the 4150), and it made a big difference on the corners even on center shots, and IMO was really necessary on the 5mm shifts. The amount of light fall off towards the edges of the frame on any shot make the CF a huge asset on the either lens 23mm or 28mm. There is a lot of work being done by the LCC otherwise.
The CF for the 23mm and 28mm is the same part.
Paul C
The CF for the 23mm and 28mm is the same part.
Paul C