i am going nuts. i tried to close one side of a loft cylinder. so "cylinder" was open, and i tried to close it with planar trim surface. but i get holes in it (see picture)

first thought: planar trim surface sucks. ok, adding another loft at the end. duplicate nurbs circle, scale down real small, and loft with the edge of cylinder. wow works. until i seen a close up render i got again holes (barely noticeable though in perspective view - but clearly visible in render). this happens with nurbs, polys (of course) and bezier

second thought: nurbs, polys and bezier are not goot to make a cylinder close. redoing the loft with a subd. and then i made it. (see picture)

i did not want to do a loft, i only wanted planar trim. and subd is not available in planar trim either and actually i did not want to use subd (another )

anybody know any suggestions on how i can make a planar trim close perfectly w/o imitating with loft+subd?

here is a close up render (production quality, reduced to 4 colors to limit bandwidth )