SOLID KUDOS to C1 on this--this will make my workflow much nicer. Just did some testing, and found a few useful things out:
- Using AP mode on the IQ4150 results in glacially slow (3MByte/sec) transfers.
- Setting up a personal hotspot on the iPad and connecting the IQ4150 to it, or connecting to a real AP is much faster (~15MByte/sec in my office, in both cases). In an architectural/landscape workflow, this is acceptable, but I'm impatient, and...
- Ethernet->USBC is faster still (100MByte/sec; i.e. full GigE speeds).
One can, and should, test for latency on this by firing up Live View on C1, moving your camera around (if shooting a static subject), and seeing how quickly the LV window updates. If connected via Ethernet, I'm seeing nearly instantaneous results; if connected via Personal Hotspot, there's minor lag but still entirely usable.
At present, C1 really doesn't like untethering and retethering to the same device over a different network. In a quick test, it seems that C1 has issues properly tearing down a tethered connection completely on the IQ4150. Haven't tried this on my other cameras yet, but: if one is tethered via WiFi and you want to switch to Ethernet, restarting C1 is usually in order. The great thing about using Personal Hotspot as your base station for this is that you can use the "swipe down from right corner" Control Strip to turn your hotspot on and off (or do it on the back, which is probably more battery efficient). I'll probably throw a few bugs at C1 around this and send logs when I get a chance to test it better, but I suspect that support for Retether is probably part of what's going on.
[pauses to catch my breath and throw my old POCP hat and nerd glasses on...]
Now, a few notes on iPad-IQ4150 workflow in general, since folks are asking. I've been using an iPad Pro 13" (2021) as my daily driver for architectural shooting the last year, and it's in general been working really well. I'm usually shooting mainly solo/with client-provided stylists with the iPad tethered while hanging off the tripod on a magic arm.
- The Ethernet connection is a bit of a bugger for those of us who wish that everything would connect via USB-C and you didn't have to travel with a fistful of f***ing dongles, but it's got a number of advantages, not the least of which is that Ethernet cables are cheap, reliable, and available everywhere and in various lengths.
- Not all USB-C to Ethernet dongles are supported on the iPad (or current Apple Silicon laptops). Apple silently deprecated some USB-C-Ethernet dongle drivers in recent macOS and iPadOS, so a device that was happily supported pre-Big Sur might not still be, and might not be on your iPad. Having used a 2017 Intel MBP as my tether device until about this time last year, I'm one to make sure there's at least a cheap docking adapter in every major bag I could possibly walk out my front door with that might contain my laptop, and about half of the adapters I owne(d) wouldn't light the Ethernet adapter up when I moved to an M1 Max laptop or connected them to my iPad. All would seem to indicate they've coalesced driver support between the two OS forks. So, if you're buying random Ethernet dongles off wherever, TEST FIRST before using them in anger, and make sure you're prepared to return what doesn't work. The usual "don't use cheap cables" digitech mantra also applies to dongles, particularly when a P1 back is involved.
- Ethernet tethering is a power hog, on both the iPad end and the Phase end. I've beat the crap out of my HyperJuice 245W battery on location and it keeps on happily powering everything. (I'm moving to ALogic's Ark, which is rated similarly, is about 15% smaller/lighter, and has a USBA port as well, which is nice for the few things I use on the road that still insist on charging via a USBA-USBC cable rather than USBC directly. Looking at you, Godox 200 charger! ;-). I've gotten through entire 8-10hr+ days on location with that setup without it even skipping a beat.
- While a male USBC to male Ethernet cable like the one @Paul Spinnler recommends above looks convenient, if you're doing long shoots, consider getting something that will let you also charge your iPad simultaneously. I usually use Belkin's USB-C/Ethernet and Charge adapter (https://www.belkin.com/usb-c-to-ethernet-charge-adapter/P-INC001.html) and it works great. So does the Anker 555 dock (https://www.anker.com/ca/products/a8383?variant=41698420949156) which also lets you plug in a USB-C camera or other device without disconnecting the dock, while charging from a power bank. I've also tested the 7-in-1 Dockteck (https://www.dockteck.com/products/usb-c-hub-7-in-1-usb-c-pd-ethernet); as a nice freebee, both of these docks also give you an easy way to ingest SD cards into C1 iPad on the road.
- All of these let you free up your back's USBC port for charging/external power. Which, with a power bank with 2 USBC outputs, you can and should do.
- In theory, the P1 back can also charge/power itself over Ethernet. USBC to PoE cables exist (that might also provide connectivity as well as power), but I've yet to test anything. If someone's come up with a USBC power splitter splitter that will also give you PoE + connectivity to the back on one cable and the ability to also charge your iPad, I'd love, love, love to know. (@buildbot, do you have anything hanging around? I seem to remember a thread on this...)