I recommend 11x14 in ULF territory. You can fairly easily buy film. Contact printing a film or glass negative is more feasible too. Remember you will be printing on the next size up paper 16x20 which is probably the last size reasonable to do in trays. The logical lens on the short side is the Nikkor 450mm f9 but you might want something faster for wetplate which would probably be a cheap brass antique lens with a hat for a shutter. For 600mm Id go the 24 Artar route but again for wetplate this would probably be too slow.

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