How do I determine what shutterspeed to use for long exposure night photography?

Question

Usually when I shoot, I look at the exposure meter scale in the viewfinder and adjust the shutter speed (or aperture). Sometimes even after doing this, I take a picture first and check it in the LCD screen to see whether it is properly exposed or not (the way I want). If it is under/over exposed, I will adjust the the shutter speed or aperture so I get the result I want. This is the technique I have been following.

Now I am going to try some long exposure photography. For example I want to shoot the skyline at night where the buildings are well lit but still get a night feeling. How do I determine what shutter speed I should use? Should I do the same thing? Take a 30 seconds picture, check the picture, and if I don't like, change the shutter speed and keep trying this?

I shoot with a 50 mm f/1.4 on a full frame and I am looking to take pictures like this one on Flickr by Matt Pasant.

Answer 1

Now i am going to try some long exposure photography. For example i want to shoot the skyline in night where the buildings are well lit but still get a night feeling. How do i determine what shutter speed i should use ?

You can continue to use the trial and error method you've been using, and that's fine, but with long exposures each test shot can take a lot of time.

Because you can trade ISO, aperture, and light for shutter speed, you can do some test shots at high ISO and large aperture to get the exposure right and then adjust those parameters and compensate with a longer exposure. For example, if a test shot at 1 second and ISO 3200 gives the right exposure, you can decrease ISO to 100 (that's 5 stops) and increase the exposure to 30 seconds (5 stops). If you don't want to mess with ISO, you can change the aperture instead, or add an appropriate neutral density filter, or some combination of all three.

It's a simple idea: for every stop that you increase exposure length, you need to compensate in the other direction with some other parameter.

Answer 2

Trial and error will get you into the ballpark with longer exposures, just as it does with smaller ones. It simply might take you a little longer.

However. Simply getting a well-exposed night time shot with a 50mm on full frame won't get you anything like that Pasant image. He also used full frame. With a 24mm lens. And from the way the colors are popped and the halo around the tower, I'd say he also did some form of HDR bracketing/stacking, and possibly some light painting (or just got lucky with the environment's lighting) with the way the piers show up in the foreground. So this could have been more than one exposure, not a single shot. Whatever his methods, there's a lot of post-processing going on here. So don't expect a look like this straight out of the camera.