I have switched to shooting tethered, for two reasons. First and more importantly I am able to focus from my desktop, with the coin imaged as large as my screen. Secondly, I don't have to keep pulling the flash card out of the camera and sticking it in my computer; the files just end up on my computer. But my computer is within range of my photo setup, at least within a long usb cable's length.
I have a Canon, and I use the EOS utility. I have mine tethered and control from my computer for a couple of reasons: First, it is much easier to see a full size picture, and adjust it on the monitor than using that tiny viewscreen. Second, I'll be viewing and sharing the pictures on my computer, so I want a really good idea of what it will look like on my monitor. Things appear differently on different screens.
I want to thank all of you for your posts. I was going to buy a new macro lens, but using my Sigma 18-250mm f/3.5-6.3 DC Macro HSM Zoom Lens on my Nikon D3100 on a good tripod with adequate lighting I was able to take some satisfactory coin photos. More practice is what I need now.
I've got the option to tether my camera, but prefer to use the 'live view' option on it.......I can zoom in, before the shot is taken, to make sure everything is in focus.