The root of my problem is my lack of adequate understanding of two things:
1 the iCloud and when it does and when it doesn't synchronise data between devices
2 the way Apple devices organise photos
My lack of understanding in these two areas is mostly quite unconnected, but what I'm asking about now is something that relates to both.
Our of the blue, my iPad stopped sending and receiving emails last week when I was away from home. Having done everything I can think of to remedy things, I have decided to do a factory reset.
(I did this procedure several years ago – I can't remember exactly what the problem was then; it was Mail related but not identical to the current problem. I followed some online instructions and the Mail problem was resolved as a result.)
When I did the factory reset last time I can't remember what I did about the photos on the iPad but now I feel the need to have reassurance that there's no way that when the procedure wipes the photos on the iPad it won't simultaneously delete the photos on my iMac. (When I delete a photo on the iPad I am confronted with the message that deleting it will cause deletion of it from the Photo Stream on all my devices.)
So far, this does NOT seem to happen, but I am very nervous that I could accidentally wipe all my photos.
As I suggested above, I am confused about the various categories of collections of photos on both the iMac and the iPad. There doesn't actually seem to BE a Photo Stream on the iMac, which might explain some of the facts.
I would have deleted all the photos on the iPad ages ago if I were not nervous about losing them from the iMac as well, because they are using up masses of storage and it seems silly to have all the photos twice over.