Tiff to PDF (multiple pages tiff, some portrait, others landscape)

Hi,
Ive been searching the forums, but im unable to find an answer.

Problem:
I have a TIFF file which I need to convert to PDF.
The TIFF file consists of pages of both portrait and landscape format.

When I only have 1 page in my TIFF I have been doing the following:

Dim sec As Section = pdf1.Sections.Add()
Dim myimage As New Bitmap(ms)

        If myimage.Width > myimage.Height Then
          sec.IsLandscape = True
        Else
          sec.IsLandscape = False
        End If

But how can I loop through the TIFF pages and (maybe?) add a new section for each page and at the same time determine if the page should be "landscape" or not.