I did a focus ramp test yesterday with the installed 50 mm lens on my RF-9060 and found out that the optimal space between material and nozzle was 10 mm (it's not the focal lenght, but how do we call this space?). That surprised me because the focus tool for this lens is 8 mm, according the written instruction on a sticker on the lens tube. So I checked the lens today (and cleaned it) and I noticed that it is a meniscus lens and that convex side was towards the worktable, so down!! That surprised me too because I thought that it should be up. I checked the internet of course to get some assurance, but I found no clear answer. Some say convex up for a meniscus lens, some say down and some say that it hardly matters.
What is your opinion / expertise in this?
BTW, the 38 mm lens that also came with my machine is a plano convex lens. Don't know why the lens types differ.