In case you happen to need to convert a PDF to a .tif this seems to be a good way.

Here is a commandline that should work well for letter-sized pages of a multi-page PDF file: (Using ghostscript)

gswin32c.exe -o page_%03d.tif -sDEVICE=tiffg4 -r720x720 -g6120x7920 input.pdf

In case you want to do this under program control you could use GhostSharp, https://github.com/mephraim/ghostscriptsharp