Originally posted by Jome Hello dear Pentaxian,
I would like to know where I can find step-up rings from 49 mm to anything that are VERY solid?
What is your definition of "solid"?
Step up rings are made of either polycarbonate (the most likely to cross-thread or break), anodized aluminum (the most common), and brass (the most durable and considered the most 'reliable').
Both Heliopan and Sensei make brass step up rings, but in the 49mm+ sizes, you're looking at mostly Heliopan.
I prefer using BHphotovideo because of their selection, competitive prices, and it's easy to filter the parameters of what I need on the side bars of their web pages.