Documents that were published before 1923 are in the public domain and no permission is needed, and if published before 1966 they may be in the public domain if the copyright was not renewed, which is likely for scholarly works. Remember that translations are new works, so it is the date of publication of the translation that matters for copyright, or the copyright date if earlier than the publication date, and it is the translator or his publisher from whom one has to obtain permission. Most copyrights of publishers no longer in business have been acquired by a publisher still in business, but sometimes it can take a bit of research to track down the current owner, if any, to obtain permission. The third step is to have a good computer, scanner, and software. The computer should have plenty of hard disk space, as each page, scanned at 300 dpi, will take up to about 100 K for the image file, and perhaps 6 K for the edited file, although that space can be reclaimed by deleting the image and other working files after they have been recognized and the page is saved as an edited file.
Flatbed scanners work best.
Digital cameras can be used, but they will need to have at least 10 megapixels before they are satisfactory for that purpose. Scanners should have a resolution of at least 400x400, and higher resolutions are desirable. Good scanners are now available for a low cost. We prefer smaller ones, such as the Umax Astra 2200, that can be carried into a library, together with a notebook computer, for documents that can only be found in libraries. Larger scanners can be faster, and have scanning plates large enough to scan two facing pages of a book in a single scan, and these may be preferable if portable use is not contemplated.