Difference between USB mass storage mode, and MTP or PTP mode

For connecting to a computer with a USB cable, many cameras have the option of using either USB Mass Storage Class (MSC) mode, or Media Transfer Protocol (MTP) / Picture Transfer Protocol (PTP) mode. Whereas it seems some newer cameras will only connect in MTP mode. What is the difference between these USB modes? Which one is better for downloading photos from my camera? Does it depend on what sort of computer I am connecting the camera to? (I know I could take the memory card out of the camera, and put it in a card reader, but sometimes that is not convenient)

1 Answer 1

USB mass storage is exactly what it sounds like: your camera presents its storage to the computer as a removable drive. This means you can poke around in parts of the storage the camera would really rather you didn't, re-format with the filesystem of your choice, copy files other than images to and from the camera, and in general treat the camera as a funny-looking USB thumb drive (possibly with unpredictable consequences).

PTP/MTP mode is a more structured way of accessing the storage, designed for moving files to or from the camera. The camera remains in control at all times, preventing you from changing storage in ways that would cause problems.

In general, mass storage mode is more flexible, while PTP/MTP mode makes it harder for the user to break things.

\$\begingroup\$ Also: the flexibility of storage mode extends not only to what you can do, but how you can do it; it's accessible to any software that can access a filesystem (your favorite file browser, rsync, etc). MTP can only be accessed by software that speaks MTP (although there are ways to partially work around this). \$\endgroup\$

\$\begingroup\$ PTP/MTP also seem to mean you don't need to eject the storage before unplugging it, while computers generally give a warning about unplugging a mass storage device without unmounting/ejecting it properly first (so perhaps a higher risk of corruption) \$\endgroup\$