Bob Salomon wrote:
Or 50mm 2.8 Apo Rodagon-N?

No. It was the "old" Apo-Rodagon without suffix. However,
I had both the latest Apo-Rodagon "N" in 2.8/50 and 4/90 on
loan here and compared them to my "old" Apo-Rodagons with
the same focal length. With a carefully aligned enlarger,
no differences visible, tested at 2x, 6x, 10x and 15x enlargement
(90mm) and 4x, 8x, 12x, 20x (50mm). So I decided to keep my old
glass. All my enlarging lenses are used at two f-stops down from
full open.

In a glass negative carrier as the lenses are designed to be used with?

Of course. I use my Durst G139 with TRINEG glass carrier and use a Versalab
Parallel laser alignment tool to align easel, lens board and carrier.

Martin