[AndrewPaulCooper]

I'm thinking about upgrading to an iMac and I am a little worried about image process flow.

In Windows I have a non backed up folder structure where;

I dump my camera data, a load of large RAW digital images (30M each) then throw the duffers, sort 'like' images (e.g. different exposures for HDR recovery) into sub-folders, do some experiments etc.

Loads of data, not worth backing up

I then have a backed up folder where;

I move images good enough to keep
and merged images (usually with their source file(s).
the native format of the program I am using
The final image in all it's glory.

Can I do this on an iMac

i.e. select a folder (and all sub-folders) to be ignored by iCloud / iPhoto to avoid filling my bandwidth and iCloud data with potential garbage?

[dcoke22]

Yep.

The stuff that the app Time Machine, gives you control for choosing things not to backup. You set this in Time Machine's Preferences.

Personally, I choose to let Time Machine backup the images I have in Lightroom, but I could easily structure the folders to make it easy to exclude some or all of those images.

I do occasionally make some time lapse movies. Sometimes I end up with 10s of thousands images that get packed into a time lapse movie. Those images do not end up in Photos or iCloud or in my Time Machine backup. I do, however, have a Backblaze account. Since they let customers backup unlimited data for a flat fee, I do let my time lapse source images get backed up to there.