Perhaps a bit controversial, but we’re at the point of seriously diminishing returns already. Typical modern 35mm negatives are frequently thought to produce usable detail for up to 6K scans, but that’s not because they have 6K of fine detail – a la Nyquist, a 6K scan is needed to accurately capture about 3K of fine detail. So a 6K scan of a pristine, high-quality 35mm negative could produce something that’s visibly better than 1080p, but doesn’t quite push the limits of 4K. But the OT negatives are neither pristine nor particularly high quality – and most importantly, we don’t have access to any of them. Instead, what we have is projection prints, considerably worse quality than negatives, the best of which struggle to have 1080p of fine image detail, and in many ways fail to match a 720p downscale of a higher-quality source, in terms of fine image detail – the grain definitely does resolve better at 4K, but so much has been wiped away by optical duplication that you’re not getting any usable image detail along with it. So IMO 4K scans are more than adequate for what we currently have access to. An upscale from 4K to 8K wouldn’t have any less fine image detail than an 8K scan, of these sources. Should we stumble across actual well-preserved OCNs some day, I’d be happy to revisit this opinion.
