I wanted to give my top three tips for photographing cityscapes at night to make better images.
Tip #1 - Ghosting is caused when people or things in your frame move during a long exposure. If people or things are constantly moving and the exposure is long enough they may not appear but alternatively you can shoot multiple frames of the scene and blend them out in Photoshop.
The use of people moving in a photo gives the scene a sense of movement and interest in an otherwise boring image
Tip #2 - Always check your histogram and expose to the right. It’s easy to underexpose cityscapes at night. You look on the back of your camera and the image looks ok... then you get home and the image is too dark and noisy.
One reason is your LCD screen on the back of your camera is backlit... the image shows brighter than it actually is. It is also a low res jpeg you are looking at... the RAW image on your computer is not as bright.
If you want the best result, you need the image to be a bit brighter than what you are seeing, it will give you some latitude with post-processing as most of the date is in the top 2/5ths of the histogram and you receive less digital noise if you shoot to the right. Always check your image histogram and dont rely as much on your back screen.
Tip #3 - Rain is one of the most challenging elements to contend with when shooting long exposures.
Water droplets on the lens are usually visible at narrow apertures, so check your lens between shots and wipe with a cloth. If using an umbrella or cover make sure to keep it out of the frame.
The end result can produce a compelling image... the reflections in ponds, the colors that illuminate the foregrounds, each offer a unique element to your night photograph.
Why don't you join Jeff Wendorff and I in Paris in November of 2018. We will be putting these techniques to the test. See the details here, https://www.kevinpepperphotography.com/2018-paris-street-photography-workshop