there i am recording for like 2 years my train rides. Sometimes people look at me weird because i record audio/Video. Are there any tricks how not to be spotted?
Sometimes you just have to have the gumption to get what you need. As a Sound designer for independent films I've had to do all sorts from pub ambience and once I needed the sound of school children in a class room (that was I nightmare). Most recently I needed the sound of a child's swing in a play ground (the public Park type ones with chains) for a horror film. A women with a child must of thought I was totally weird pushing this empty swing. But needs must.
You can get small recorders that are discreet. But the smaller they are the poorer the quality. I use to use an Olympus LS11 about the size of a cell phone. But my Marantz 661 is far better quality but it's the size of a brick.
I just go out and record if people ask you to leave because your on private property etc then do so, as long as you get what you need. But don't let them try and take your gear off you! Tell them to go **** themselves.
Privacy in our times is shrinking at a faster rate than Iceland and the North Pole. You might want to take it into account that it matters more for some people than others and some can feel awkward or under surveilance when big microphones or cameras are pointed their ways.
Other than that if you want to capture strictly train mechanical sounds it's obviously better to be in place with as little chatter as possible.