TIFF is a perfectly good archiving format for raster images. TIFF is capable of good compression to save space. As TIFF is a raster image, there is not font information to save. As far as I understand it you can import TIFF into a PDF and it just provides a wrapper around the TIFF data. I don't see any purpose to importing to pdf.
Thank you Michael. lets say we "have" to convert them into PDF or PDFA (because of program requirement) then what will we loose (if any) when we convert them into PDF. Second question, lets say we have to convert them into PDFA, then can we still preserve archiving abilities even though it is converted into PDFA from a TIFF format?
Perhaps there is no gain. What drives the migration to PDF/A might be more significant.
While more government and enterprise entities in the United States are requiring it for digital submissions/records this growth is slower than in Europe.
I suspect that more entities engaged in international commerce will be using PDF/A for their archived records.
Regardless, a useful information resource for PDF/A (when you find yourself having to go to it) is the document "PDF/A in a Nutshell".
Having Acrobat Pro's support of Standards is useful when having to perform a "migration" to an ISO Standard associated with PDF.
The obvious point is that with PDF (and PDF/A) you can OCR the pages and convert the text into searchable, semi-accessible data!
You won't be able to make fully-accessible PDF/A-1a files as the OCR system cannot interpret the semantic structure of the file (it won't know what makes a H1 header a H1, where paragraphs flow to, etc.) but you can certainly make PDF/A-1b files.
Converting scans to PDF may or may not downsample the image, and may or may not convert the text into simulated fonts - it depends on the options you choose when applying OCR. Unless there's a need to preserve the TIFF data exactly (e.g. for legal reasons) the compression in Acrobat X can usually shrink a mostly-text-based scan by a factor of ten or more, without any real loss of fidelity on screen.