Just a question, what Fujinon 600 is ? The T or the C ?
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Congratulations, this is an impressive asset !
The Nikkor T was very valued for the fieldability of the kit, if wanting to carry 3 long focals then quite weight and space were saved, and using a single shutter instead 3 also added exposure consistency, while also saving bellows extension. There are not much convetional choices in those lengths and some people used process lenses instead, like the APO Ronar, obviously commanding longer bellows than the Nikkor kit. The Nikkot T kit also has very good coatings. A "rival" glass is the APO Tele Xenar 800, a massive and ultra expensive/scarce thing, but reportedly it is better, specially in the corners, but in landscape, most of the times, what the corners have is irrelevant, in the top corners we may have sky/clouds and in the bottom corners we may have something near that is not in perfect focus.
Instead Christofer Burkett mounts the APO Tele Xenar 800 in his Calumet C1 to take details, for his kind of photography that glass had an advantage, specially considering that it could follow abig enlargement (with APO Nikkor EL 480 enlarging glass!) to craft museum ilfocrhomes.