1 voteAdminPictomaphone (Admin, Pictomaphone) commented
Oh man, I wish there was an API for reading EXIF in the WP7 SDK. I had to write my own parser to read the exif data from the jpeg file.
Meanwhile, I just checked on my WP8 device and I'm seeing the same behavior as you. Maybe WP8 writes EXIF data to the file differently than WP7? I'll have to look into it. EXIF is a kind of a crazy format with different manufacturers doing things slightly differently.AdminPictomaphone (Admin, Pictomaphone) commented
Some phones don't save all of the exif data to the jpeg file after taking a photo, which could explain why exposure time is blank.