Guide · How it works
How camera remote live view actually works
Getting the camera’s picture onto a phone sounds like screen mirroring, but it works quite differently. The camera is running an old file-transfer protocol, and live view is something it can do on the side. That explains a lot of odd behaviour.
What PTP-IP is
PTP, the Picture Transfer Protocol, is the standard way a camera talks to a computer. It started on USB. When you plug a camera in and see a list of photos, that’s PTP.
PTP-IP runs the same protocol over TCP/IP. The camera waits on the network and the phone connects to it.
Once connected there are usually two channels. One carries commands and data, such as fetching a file or firing the shutter. On the other, the camera reports events like a new shot or acquired focus, which is how a remote app keeps up in real time.
Live view is a repeated request for the current frame. It isn’t a video stream. The frames are pulled one at a time, which is why quality and size can be adjusted, and why lowering them eases the link straight away.
Where the lag comes from
The picture goes through four stages on the way to your screen. The camera encodes it, it crosses the wireless link, the phone decodes it, and the screen shows it. If any stage slows down, the view stops feeling live.
The camera itself matters most, since an older processor won’t be quick even on an empty network. Next comes the link. 2.4 GHz is packed at events, so use 5 GHz if the camera offers it.
Maxing out live view quality adds load, so step it down when responsiveness matters. With that many variables, be wary of anyone quoting milliseconds. We don’t, and measured per-model data will be published at launch.
Which cameras are covered
Zlens has 74 model profiles so far.
- Sony, 19 α1, α9, α9 II, α7 II, α7 III, α7 IV, α7R II through α7R V, α7C, α7C II, α6100, α6300, α6400, α6700, ZV-E1, ZV-E10, ZV-E10 II
- Nikon, 19 Z 9, Z 8, Z 7, Z 7II, Z 6, Z 6II, Z 6III, Z 5, Z 50, Z 30, Z f, Z fc, D850, D780, D750, D610, D500, D7500, D5600
- Canon, 18 EOS R5 Mark II, R5, R6 Mark II, R6, R7, R8, R10, R, RP, EOS 5D Mark III, 5D Mark IV, 5DS R, 6D Mark II, 7D Mark II, 90D, 80D, M50 Mark II, M6 Mark II
- FUJIFILM, 18 X-T1 through X-T5, X-T30, X-H2, X-H2S, X-S20, X-E4, X-Pro2, X-Pro3, X100F, X100V, X100VI, GFX100 II, GFX100S, GFX50S II
A profile describes what the protocol allows. It isn’t a hands-on test, and per-model results will be published at launch.
Where it earns its place
Astrophotography
The hard parts are focusing and not touching the camera. Magnified live view with focus peaking is far more precise on a phone than on the rear screen, and once the exposure starts your hands stay off the body.
All-night time-lapses rely on the intervalometer, and a power cut or a crash can waste the whole night. Zlens picks up again after either.
Long exposure
Timing a bulb exposure and watching the histogram is easier with the phone in your hand. In Zlens the intervalometer and bulb mode work together, and you get a sound and an on-screen alert if the shutter drops below the limit you set.
Group shots and self-portraits
You need to be in the picture and still check the framing and whether anyone blinked. That only works when live view, touch focus and the shutter are all in your hand.
How Zlens handles it
Live view quality and size are adjustable. Focus peaking, histogram, zebras and waveform are all there, with multi-point magnification for checking focus.
Shutter, aperture, ISO, white balance and focus mode can all be changed from the phone, along with touch focus and power zoom. A red night mode protects your dark adaptation.
Zlens isn’t out yet. The download link will go on the home page once it’s ready. Menus in the official apps change with firmware and app versions, so go by the menu on your camera.