Just a heads-up

if you did a photograph for aesthetic reasons or something, carry on, but if you did so because you couldn't find a good way to take a screenshot, I usually use the command-line grim utility. I'll sometimes do something like $ sleep 3; grim on one workspace, then flip to the one I want to screenshot, so that three seconds after issuing the command, it'll save a screenshot.

I'm sure that there are also other utilities out there, and KDE Plasma may have its own screenshot utility built in somewhere. But I can vouch that grim will do it.