... my lens was the APO-Nikkor 610mm f/9, not 900mm.
I used it on an 8x10" camera back in the dark ages of [sheet] film.
I remember looking at some wonderful 10x8" b&w prints back in the early 80's and feeling i was nowhere near the level of richness & quality they'd achieved.
The gallery owner sympathised, then said not to worry.
It turned out these were contact prints direct from the source 10x8" sheet film negs!!
This in turn sent me down another rabbit hole (Pentax 6x7...)