The water surface looks so smooth and the lights have the rays coming out. What are the techniques to get such image? What kind of camera settings a dslr camera should have?
This looks to be a fairly standard long exposure. The shutter speed needs to be slower than the 'period' of the waves (or 1 over the frequency) - this will cause the water to look flat. The colour suggests that the scene is largely moonlit which is why it's quite bright. With most 'sea' waves, you're looking for a shutter speed of about 10 seconds (or more) for smooth water.
The sharp focus on both the bits sticking out of the water, and the city, suggest a larger depth of field - which suggests you'll also want a small aperture (larger number). Although I expect the aperture was mainly made small to give a longer shutter speed.
To get this type of shot you'll be needing a tripod, and you'll want a low ISO and possibly a neutral density filter infront of the lens to lengthen the shutter speed even more. You'll also need some patience and practice along with some very good light. Shots like this come from spending many days stalking the perfect light conditions, in the cold and dark not just from knowing how to use your camera when you get there.
- You need to shoot such a scene just after sunset or just before sunup when there is still just a bit of light in the sky.
- You need to use a very long exposure time to smooth out the water and give it that ethereal feel. At a very minimum you should expose for 15-20 seconds. Even longer is usually better.
- You need to use a fairly narrow aperture (high f-number) to get most of the scene in focus. Just be careful not to go so narrow that diffraction starts to be noticeable (probably around f/22 with a FF camera, f/16 with an APS-C camera). If you can get by with f/11 (FF) or f/8 (APS-C) and still have the DoF you need then all the better). Use the hyperfocal distance at an aperture that allows the nearest pylon to be just inside the depth of field.
- You need to use a low sensitivity, such as ISO 100, to allow a longer exposure.
- You need to have the camera immobilized to prevent blur caused by camera motion. A tripod is typically used for this type of shot.
- You may also need to use a graduated neutral density filter to get the sky and the water approximately the same brightness.