Right! Never too late to learn! ANY version of Photoshop will do, and you don't need to use any of the options that are needed by graphic designers to vie in effects for full-page color ads and
album covers (if there are any albums any more). As always, and as with cameras, the professional equipment that looks daunting ends up doing the job most easily as well as best.
Mac makes sure that kids can use their machines, as well as their great grandparents: that's great and
good for NASDAQ, too, which is
good for R&D. But, also, Macs do facilitate the
work of that minority of minorities: scholars. And, of course, artists. But for coins, I assure you, you only need a
bit of Photoshop.
Here is my advice.
As Akropolis said, start with a
very good coin.
Start by mastering your camera. Focus and exposure and lighting.
Start by learning to optimize the best and most essential features of Photoshop. Their manual is aimed at graphic artists, the "cool" stuff, but you don't need to worry about its full potential.
Don't get fancy till you are comfortable and skillful in the basics.
Then you can start doing 'interesting' things, both with lighting and with post-processing.
Pat L. (the voice of experience, starting with a lousy camera and Photoshop 3 and having struggled with every transition the industry can throw at us--that is why mastery of the basics is the most important).