From someone who worked ~30 years in the documentation business (user guides, reference guides, owners manuals, etc.):
No, RTFM is never useful and usually rude for several reasons, but here are 2 that should be enough:
- Camera reference manuals are pretty dry reads, giving only the function and brief parameter descriptions without a lot of conceptual 'how to' text to help people wrap their brains around it
- When you tell someone to RTFM, you may not be considering that persons reading or comprehending abilities in your arrogance.
There are several better ways to hand this, such as:
- Just move along and say nothing if you don't intend to help. Leave it to others.
- Giving a bit of description with examples and/or screen shots for clarity is helpful in ways that go beyond the dry reference page. This is true for the software we use (Adobe, C1) as well as camera gear.
- Give that help, but (as mentioned by someone else) give the page number in the owners manual, maybe a screenshot of the page. When you do this, you're already pointing out that there's a manual with the information — there's no need to add "read the manual".
Chris