In a recent thread started by Michael Heald Ted Harris says: "I find that scanning at the maximul real world resolution of your scanner produces the best results for a "master" file that you can then manipulate as needed depending on the final image. In terms of all of the consumer scanners this will mean setting your scanner to sample at ~ 2400 spi (depending on the settings)." So Ted says to scan at the maximum optical resolution rather than the maximum resolution stated by the manufacturer.
OTOH, in the same thread robc says: "I would scan at 4800ppi which gives you an image of approx 24000x19200 pixels."
So one says to scan at the maximum optical resolution of the scanner, the other says to scan at the maximum resolution stated by the manufacturer (robc was talking about the Epson 4990, which Epson says has a maximum ppi of 4800).
I had always understood that there was no point in scanning at a ppi higher than what the scanner could resolve, that while a scanner would create a file based on the maximum stated resolution there was no benefit in doing so if the scanner could only resolve a lesser number. However, robc's statement about scanning at the maximum spec resolution is the second time I've seen that suggestion here and both robc and the other person, whoever that was, seemed to be knowledgeable about scanning. I'm not.
So I'd like to know whether there is any kind of a consensus about this. Do you scan at the maximum optical resolution or the maximum resolution stated by the manufacturer for best results, forgetting about what size print you want to make since either way you'll presumably downsample once you decide on that.