PTP vs MTP
Picture Transfer Protocol vs Media Transfer Protocol
PTP is the standard protocol cameras use to transfer and control photos over USB; MTP is Microsoft's extension of it for phones and media players.
When you plug a camera into a computer or phone, the two have to agree how to talk. Most cameras offer PTP (Picture Transfer Protocol), a standard built specifically for cameras: it lists the photos on the card, downloads them, reports new shots and, on many bodies, accepts control commands. MTP (Media Transfer Protocol) was built on top of PTP by Microsoft to move music, video and files to phones and media players.
A third option, USB mass storage, makes the camera look like a card reader. It's simple for copying files but can't report new shots as they happen, so it's no good for tethering.
How it works
PTP is an international standard (ISO 15740). The host opens a session with the camera, reads its device information, and asks for storage, object lists and files using standard operations; camera makers add vendor extensions for their own features. MTP keeps PTP's structure and adds properties for media libraries. Because MTP is a superset, many hosts that speak MTP can also talk to a camera in PTP. The same protocol carried over a network instead of a cable is PTP/IP.
An example: a Nikon that mounts as a drive
A photographer plugs an older Nikon into an Android phone and it shows up as storage with folders, but the tethering app sees nothing. The camera's USB option is set to mass storage. Switching it to MTP/PTP in the setup menu makes the camera announce itself as a PTP device, and the app starts receiving shots.
PTP and CloudTether
CloudTether talks PTP to the camera over USB and PTP/IP over Wi-Fi. That's why the camera's USB mode matters: Sony needs PC Remote and Fujifilm USB tether shooting; current Canon and Nikon bodies work as they come. If a body mounts as storage, set its USB option to MTP/PTP. More in camera not detected over USB.
Why the distinction matters
In everyday use you rarely choose between PTP and MTP directly — the camera menu decides. What matters is avoiding modes that aren't PTP at all: mass storage, webcam (UVC) and USB streaming modes all present the camera as something else, and a tethering app won't find it.
Tips and common mistakes
- Webcam and streaming modes look like a camera to a computer but aren't PTP — switch them off to tether.
- Only one app can hold a PTP session with a camera at a time; quit the maker's app first.
- If a camera appears as a drive, look for an MTP/PTP or PC connection option in its USB menu.
Put it into practice
CloudTether tethers your camera to your phone and delivers every shot to the cloud, live as you shoot — no laptop.