We've just been sent the largest and highest resolution iphone panorama photo we've even seen. Taken on the iPhone 6+ a customer just sent through a whopping 13600px wide by 2800px photo - 38MP! - and printed at 36" wide this produced a photo at 380ppi. This is truly crazy stuff.
But how do you make sure that you send to us the full-size image in these confusing days of iCloud Photo Stream vs iCloud Photo Library without having to connect your iphone to your Mac using a wire (it's 2015 after all!).
Well in the new Mac Photos app (with the latest update of Yosemite) you can choose to turn on iCloud Photo Library to keep all your photos stored in iCloud to then be sent to all of your devices:
However to ensure the full size version of the panorama photo is actually downloaded to your Mac (to then upload to us to get printed) you need to make sure you choose 'download originals to this mac' otherwise you will be served a scaled down version and we don't want to waste any of those pixels especially when choosing the 150" wide print!
iCloud is a free service for up to 5GM of storage, but the majority of people will have a library way in excess of this and a large library of 500MB it will cost you $9.99 a month. Also using iCloud Photo Library on your iPhone essentially makes Photo Stream irrelevant and you will no longer see this as an option in your photo app.