I have LR6 working perfectly well on a 5 yr old MacBook with High Sierra OS. I have been given an even older iMac with Catalina OS. Is there a way to be able to use both machines with LR6? If not what is the best way forward?
You cannot install LR 6 on Catalina. The best way to move forward is to upgrade to Lightroom Classic 11.0, which is the direct successor to LR 6, and can read your LR 6 catalog. Lightroom Classic 11.0 is subscription only.
that's useful info. Thanks. So i have to commit to £120/ year for this? Seems expensive!!!
No one said you have to do anything.
There are a huge number of new features in LrC 11 which in my opinion is worth it, compared to what you have in Lr 6. But really, its up to you, if you don't feel its worth it, then don't pay for it.
haha. I know, but ultimately to use LR6, which I bought, on my "new" old machine, I have no option but to pay £120 for that privelege!!! If my catalogue is backed up on an external HD, can I plug that into my new old machine and use it that way?
Again, the issue is installing LR6 (its installer is 32 bit) on an OS that demands 64-bit. You could boot into an older OS that supports 32bit apps, run the installer, then boot into Catalina and run LR6 with some caveats. LR6 is a 64-bit application, it is the installer that is an issue at this point.
You can also get yourself a modern version of Lightroom Classic for far, far less than £120 per se. You will need to subscribe to the Photo plan.
Your catalog should be fine if you stick with LR6 of course and no, that's not the case as you update that to use modern versions of LR. So you have to decide if you'll stick with LR6 and at some point, not update your OS (it will eventually break and some stuff is broken already), no bug fixes, camera support etc, if you can install it, or move forward and subscribe to LR.
I have been given an even older iMac with Catalina OS.
The fact that the iMac is older probably means it can run versions of macOS older than Catalina. So one option you have is to reset the iMac completely and install a version of macOS that’s compatible with Lightroom 6.
Start up the iMac in Recovery mode, and erase its storage. (This is probably a good idea anyway, so you get a system that’s as fresh as it would be from the factory, with no personal info or files carried over from the previous owner.) Then install macOS 10.14 Mojave or earlier, any version of macOS that Lightroom 6 supports or can run on. Then you will be able to use Lightroom 6 indefinitely. What “indefinitely” means is that when that iMac finally dies, or if for any reason in the future you must move to a Mac that won’t take macOS 10.14 or earlier, then you will no longer be able to run Lightroom 6.
If you want to explore the option of setting up the iMac to run Lightroom 6, what year and model is the iMac?