Online tools to convert TIFF to PDF are best suited for users that only have a few TIFF files to convert to PDF, since converting TIFF to PDF online is a slow process. Some tools that allow you to convert TIFF to PDF online include OCR, which makes the PDF files text-searchable. If you have many documents to convert, you should consider purchasing commercial software that allows you to perform batch conversion.
Related knowledge of photo editing software:
Tiff to PDF (tiff2pdf) v3.3 Intro
TIFF To PDF ActiveX Component 2.0.2009.1221 intro
DreamSys Tiff to PDF Converter
Converting TIFF to PDF Online vs. Using Proprietary Software