We have this question about earplugs What kind of earplugs are best for concert photography?, which has remained open by consensus despite some interest in closing it as off-topic. There's also this lovely one about shoes: What kind of shoes are best for wedding photography?.
We also get a bunch of printer questions, like, recently:
- Why do professional printers still feature cartridges?
- Best way to avoid print head clogging when not using printer?
and these also generally get some back-and-forth on topicality.
Meanwhile, we've generally decided that questions about industrial optics without applicability to general photography are off-topic, as are questions about using cameras to measure things, and questions about video.
What's the difference here? Why does one category — stuff which is only peripheral to this light and optics and recording medium thing — get a pass, while the other does not?