The KDE4 Kamera library used the icon 'camera-photo'.
This icon is a part of the oxygen-icons set.

When I started porting Kamera to KF5/Qt5, I didn't have oxygen-icons installed (Oops...)
I replaced the icon using QIcon::fromTheme("camera-web"). This icon (now that I've found the intended 'camera-photo' icon) is pretty similar, but not the same. 'camera-web' is a part of the Breeze icon set.

My questions are, is there some rule governing the choice of icons that may not be available?
Should I check for oxygen-icons as an optional dependency? (And if so, should I change the icon based on it's availability?)
Is it generally safe to assume almost everyone running KF5 is more sensible than me in installation choices and has oxygen-icons?
It seemed to me than 'breeze' was the default in Plasma 5. Should I therefore stick with an icon present in 'breeze'?

Some guidance would be appreciated! (And apologies if this isn't the right place)

chrisb2244 wrote:The KDE4 Kamera library used the icon 'camera-photo'.
This icon is a part of the oxygen-icons set.

When I started porting Kamera to KF5/Qt5, I didn't have oxygen-icons installed (Oops...)
I replaced the icon using QIcon::fromTheme("camera-web"). This icon (now that I've found the intended 'camera-photo' icon) is pretty similar, but not the same. 'camera-web' is a part of the Breeze icon set.

Some guidance would be appreciated! (And apologies if this isn't the right place)

There is a camera-photo icon in Breeze (on GIt anyways).

chrisb2244 wrote:My questions are, is there some rule governing the choice of icons that may not be available?
Should I check for oxygen-icons as an optional dependency? (And if so, should I change the icon based on it's availability?)
Is it generally safe to assume almost everyone running KF5 is more sensible than me in installation choices and has oxygen-icons?
It seemed to me than 'breeze' was the default in Plasma 5. Should I therefore stick with an icon present in 'breeze'?

No, we add the icons as we make them.

Unless you really, really want to use Oxygen then yes. Otherwise no, just Breeze.

... however Oxygen is still installed as a dependency on some distributions. So it's likely that a lot of users will have them.

Breeze is the default so yes.