I'm just going off what others have said here and to convert to .dng
I'm pretty clueless as you can see and have no idea of the difference between .tff and .dng
A TIFF is a (normally) non compressed image format, usually saved from another format like RAW, as there are only a few cameras that cam save as a TIFF in camera. Because of that it is a large file, which is good because you want the most data you can get when editing. It is a rendered file though, and any changes to the image are altering the actual pixels. Better than a JPEG, because that has been compressed to some degree, and some information has been thrown away. Whether you can see the difference in a TFF and a high Quality JPEG is debatable. And depending on what you actually want to do to the image editing wise, there may not be that much difference between a TIFF and a high Quality JPEG.
A RAW, or DNG file are not an image files, they are data files, which is why you normally need software to even see them on your computer, never mind process them. The DNG, unless a native format of the camera, (I think Leica and Pentax may offer that as an option) the DNG Converter software converts the cameras RAW into a DNG, which is a 'wrapper' for the RAW file from your camera. It retains the benefits and editability of your RAW file, but the DNG 'wrapper' makes the file compatible with older software. You also have the option to have the original cameras RAW file saved within the DNG file, at the expense of a larger file size.
And why RAW or DNG? Because any edits you do to colour, white balance and exposure etc, are manipulating data, rather than pixels. You have more leeway to make changes to the data than the pixels, with less visible side effects. I rarely have to go into Photoshop because the Adobe Camera Raw and Lightroom RAW processing options are so powerful.
For some JPEGs are enough, and if they want to edit, they are happy with those files, for others who want to edit their images, and would like the best possible file to edit, RAW is the best option in most peoples opinion.
