What shutter speed should my Nikon D3100 be on for night pictures?

What shutter speed should my Nikon D3100 be on for night pictures?

Matters on your other settings.

For night pictures, you need high ISO's, around 1600, large aperture, preferably the max your lens can do, and from there your light meter will tell you what shutter speed to use

sometimes it is just light enough that you can shoot with over 1/100th of a second, but most times its usually 1/50th or below

If you have to handhold your camera then you'll need a fastish shutter speed (1/100) which will mean needing to increase the ISO, BUT most night photography is done on a tripod, so shutter speed can be as long as you need.

For night photography shoot in Manual mode (M). You should have the ISO as LOW as possible (ie around 200) for best image quality and have the aperture around f8-f11 for good depth of field. You may have to focus manually if its very dark & the AF is 'hunting', but for city/street scenes there's usually enough light for the AF to work fine.

Having sorted out aperture & ISO, then the shutter speed will depend on how much ambient light there's - experiment. Try, say, 8 seconds. If its too dark then give it longer, if its too bright, give it less time.

Night pictures of what?

How will you support the camera?

Do you know how to maximise stability?

Will you be you be using a VR lens?

Which VR lens?

Night scenes should be done on a tripod. At f/8 and ISO200 you should be getting shutter speeds in the 30 seconds-1 minute mark.

Available light (no flash) night portraits will be different. You need to keep your shutter speed to around as slow as you can hand hold. With a new VR lens that would probably be around 1/15-1/30, with a non VR lens, it's 1 divided by the focal length (e.g. With a 105mm lens you'll want to shoot at 1/100). This means you'll need to push ISO up to 800+ depending on the light available and whether you have VR or not.

Flash, night portrait. Another different game. Use diffuse light, at ISO of at least 400, shutter speeds of 1/10, and second curtain sync.

As others have said, it depends on what you're photographing and what you're using alongside your D3100. A tripod, flash, VR (vibration reduction) or similar lens all have an effect on what you can do and still achieve reasonable results.

Shutter speed is just part of forming a properly exposed image, and with night photography, the definition of 'properly exposed' varies depending on the scene and the effect you're looking to capture.

The good thing about digital photography is that it doesn't cost you anything to experiment. If the results don't work out, just delete them and thats the end of that.

If you want to get the feeling of points of light in general darkness, you'll want to set your camera's metering system to under expose. The camera's meter wants to make everything mid-grey, but what your eyes see is darker than that, mostly, especially when you're comparing it to the illumination provided by, for example, a street light.

To avoid camera shake, you should set your camera to about 1/focal length of the lens being used (eg 60mm lens, 1/60th shutter speed). If its a VR lens, you can go much slower than this, but it'll vary depending on posture and the exact lens being used, so you can experiment here to find something that works for you. When photographing people, you'll need to be aware of their motion too, so a shutter speed of 1/20 or 1/30 would be a good start.

If you're photographing moving vehicles and want to get decent light trails, you need a shutter speed that is several seconds long, but to keep the camera stable for this you'll need a tripod.

Anyway I could go on and on, but the best advice is to experiment a bit and see what you come home with. Always look to what you can learn for next time.