I am new to digital photography, but I've been shooting with a Fujifilm x100s camera that saves to .raf format. When I use Fujifilm's .raf to .tiff converter, it asks me what dpi I want the image in. I think I'm a bit confused. If .raf and .tiff are supposed to be lossless, then when the .raf gets converted to .tiff, the dpi will be whatever is required by the original file? No? Maybe I'm missing something. Thanks all for your responses.
RAW files are not images and do not have attributes as DPI. Moreover DPI is interesting when you print the image. So when you convert RAW to TIFF this attribute is added from the software just in case (w/o specific reason)
For the test you can convert to TIFF with the same setting but different DPI and then compare those images and you will see they are the same (pixel by pixel)
There is no real "DPI" in a photo. Inches of what? If it's a macro photography you can have tens of thousands of pixels for one inch of real life object, while pixels in Hubble images can be megaparsecs apart. Which is why cameras don't set the print definition in their JPEGs (when you see 72DPI it is just a default value, that corresponds to the definition of CRT displays of yore).
The TIFF file, being a format used for print, can have a print definition (which is merely "metatada", in other words, indications that can be changed), which in turns sets the intended print size (
print size= size in pixels / print definition), so your software lets you set one if needed, but this is just for completeness and not terribly useful.