Second visit to Hope Cemetery

So I went back to Hope Cemetery after work today. I got out of work at 5, then I was there at about 5:30 or so. The light was beautiful because it was orange, and it was shining on all the tombstones. Unfortunately, a lot of my pictures came out darker than I would like. I'm not a mechanical person, so I really need to practice with the ISO and aperture settings. Really basic things that I'm still embarrassed that I miss up. I tried to pay special attention to the shadows, and the way that they fell on the graves, and how the stones cast shadows on each other. I was also pleased to notice that the leaves are finally starting to fall.

Anyway, I have this idea. I was passing by this couple who were planting flowers at a grave. They were obviously mother and son, and it was really sweet. I was thinking that maybe I could try taking pictures of people in graveyards, the way they are interacting with each other (or the graves), and what they are planting. The problem is, how do I go about this? Do I go up to them and tell them that what they are doing is very sweet and I want to photograph them? Or do I hide in the bushes and snap them as they're going about their business? Would it be rude to go up to people when they're mourning their loved ones to ask for their picture? How long would I have to sit in a graveyard while I waited for people to show up?

Oh, I want to say that I haven't edited these photos yet because I was really excited to post them.