Ben Diss said:
I wonder if I'd do better with a 450mm Nikkor-M f9?
As far as the film is concerned, they are about the same.
The Artar/Ronar... etc. has the signature of being slightly low contrast ( this is not a bad thing ) with true colors and extremely high resolution. It has a narrow field of view: a 240 would not, for instance, cover 8x10. It has been a traditionally desirable lens for shooting 8x10, coupled with a 230 - 250 wide coverage lens like a dagor or wf ektar.
The M Nikkor is the most highly developed of the apo-tessar type lenses, and has a slightly higher contrast than the Ronar.
In use, either needs to be mastered for portraits. They can easily be too cruel until you learn to see as they do, and use gentle lighting and careful development.
In the old days, these lenses were avoided for portraiture because the lighting was usually too harsh and every little flaw was exaggerated. Today, with faster films, a general philosophy toward lower contrast negatives, and larger, softer light sources, it is commonplace to use these lenses for people.
One pleasant characteristic of the Artar/Ronar is that they are easy to use wide open: the image is clear enough to compose and focus, and even shoot. F/9 is fast for a 480 !
You have a perfect lens. The Nikkor needs a master's touch to control it, and even then, may tend to be too harsh. The Ronar will be splendid for you.