How to set timer in nikon d3100 - Nikon D40x Digital Camera

SOURCE: Nikon D3100 - how to

For Quick Response Mode and other Release Modes, please see "image1":

image 1


For remote control shooting or Bulb mode, see "image2":


image 2

SOURCE: What settings would you use on the Nikon D3100

Hello
Here are some general guidelines for shooting fireworks:-
Get a good position! Try to determine approximately where the fireworks will be bursting. And get a spot with an unobstructed view of that area. You'll probably need to show up early to get a good spot. Figure out the wind direction and get upwind of the fireworks so that your shots aren't obscured by smoke blowing toward you. Find a spot where you can avoid getting a lot of extraneous ambient light in the picture, as this will cause an overexpose.

Set the camera on the tripod. Don't extend the legs or neck of the tripod. Keep everything close to the ground to keep the camera as steady as possible.
Ensure the camera settings are correct. It is best to set these well ahead of time, as it may be difficult to see your camera controls or your checklist in the dusk or dark. But it's wise to double-check now.
Set your focus to infinity. You're generally far enough away from fireworks that you can adjust your lens focus to infinity and leave it there. If you want to get a closeup of a small part of the burst, you may need to adjust the focus as you zoom in. If you want to include buildings or people in the background, you may want to bring these into focus. Avoid the use of auto focus if possible. Most cameras have difficulty adjusting focus in low light conditions.
Use a smaller aperture. Set the aperture in the f5.6 to f16 range. F8 is usually a good bet, but if you're shooting with ISO 200 film you may want to kick it up to f16.
Turn off your flash. The fireworks are bright enough, and your flash wouldn't effectively reach them anyway.
Take off any filters or lens cap before shooting. If your lens has IS (Canon) or VR (Nikon),Turn it off before shooting. If you are shooting with an SLR or DSLR camera, chances are your lens has the IS (image stabilization) or VR (vibration reduction) feature built in. And if you have IS or VR (it is essentially the same thing, but Canon and Nikon just had to label it differently), then chances are you are used to leaving it on close to 100% of the time - which is generally a good idea. IS/VR is meant to sense the vibration (the shaking of you hands, mostly) and compensate for it. When it does not sense any, it... creates it. Turn it off in order to get sharper images. This tip goes not only for shooting fireworks, but is valid any time you shoot off a tripod.
Frame the picture before shooting. Look through your viewfinder during the first few bursts and figure out where the action is. Point your camera at that spot and leave it there. You don't want to be looking through the viewfinder while you're trying to shoot, because you'll likely shake the camera or your timing will be off. If you're trying to get closeups, of course, your framing will need to be more exact and you'll probably have to play with it more. Once again, frame carefully to exclude other light sources that might distract from the fireworks or cause your photos to be overexposed. 5Keep the shutter open to capture the entire burst. Set the exposure to the maximum length. To get the sharpest image it is best that nothing comes in contact with the camera during the exposure. Use the automatic long exposure of 30 seconds or more. If your camera does not have an automatic long exposure the use of a cable release is OK. Use the BULB (B) setting, which will keep the shutter open as long as the button is depressed. A rule of thumb is to open the shutter as soon as you hear or see the rocket shooting into the sky and to leave it open until the burst is dissipating. This will usually take several seconds.
Spice it up. Even good pictures of fireworks can be boring if there's nothing to distinguish them. You can make more interesting photos by including buildings in the background or spectators in the foreground. Choose your shooting location to try to get an unusual and unique perspective on the show if Possible.
Hope it helps, if so do rate the solution

SOURCE: setting dpi on my nikon d3100

DPI (dots per inch) is an output specification and is irrelevant to the camera. The camera puts a value into the field simply because it has to put something there. The DPI is set by the printing program when it prints a picture. A picture printed at 4x6 will obviously have more dots per inch than the same picture printed at 8x10.