Long Exposure of Dallas, TX

I took these shots in Dallas over looking a bridge by my uncle's house that I was staying at. I turned my shutter down super low and experimented with my ISO until I got the light just right and fired off these beauties. I typically don't like to mess with long exposure a lot because I feel that it's a major pain in the ass to get back to more basic setting and is only useful for low light shots. Also sense you have to lower the iso and close the aperture to compensate for the amount of brightness you'll gain from the low shutter speed it just seems like a lot of work. Any photographers know of ways to achieve these kind of effects with less effort?