"What is the best way to convert an old, physical book into a PDF file for digital preservation?"

Adobe Acrobat Online Services allows direct conversion of eBooks to PDFs by uploading the file on their webpage.

Smallpdf, Word, Preview, and online converters like PDF2GO also facilitate eBook to PDF conversion.

Dedicated document scanning apps on smartphones can convert physical books into PDFs by scanning pages.

Adobe Acrobat's "Save As" feature can convert files to PDF, given it supports the original format.

Online tools like Smallpdf enable conversion of various file types including Word, Excel, PowerPoint, and images to PDFs.

Converting webpages in Safari to PDFs is possible through File > Print > PDF > Save as PDF.

A document scanner mobile app like Adobe Scan and CamScanner can convert physical books into PDFs.

EPUB to PDF converters allow direct conversion of eBooks in EPUB format to PDF format.

Online tools like Online Documents Converter and Zamzar can convert various file formats to PDF directly from URLs.

Using screen capturing tools to convert documents can leave out metadata and possibly violate copyright laws.

OCR (Optical Character Recognition) technology can be used in PDF converters to recognize text in scanned images or documents.

PDF editing tools allow for the addition of various multimedia elements, interactive buttons and widgets in the converted files.

The process of converting physical books into PDFs by scanning can cause significant degradation to their bindings.

Quality concerns should be addressed while converting via scanning, including resolution, color depth, and page alignment.

Certain DRM-protected files may not be convertible and may require extra steps to remove DRM restrictions.

Legality of removing DRM is questionable and can result in fines or legal action under the Digital Millennium Copyright Act.

Meta information from the source file can get lost or altered during the conversion process.

Complex formatting features in the source file may not translate perfectly in the converted PDF.

Online conversion tools have varying file size limits, often between 10-50MB.

Large files will require alternative methods.

Converting files with sensitive information should be done on secure platforms using HTTPS connections to prevent data leakage.