Kind of hard to specify because it depends on the ambient light, distance, etc., but the general rule is to shoot in manual mode with auto ISO off, keep ISO fairly low, aperture somewhere in the middle range, and use a time exposure. Open the shutter when you presume a shot is about to occur, allow one or more skyrockets to be fired, and then close the shutter.
The last fireworks I shot, I used a time exposure of varying length, and got pretty good results at F10 and ISO 200. The lens was set fairly wide, but what focal length you use will depend, of course, on how far away things are.
A tripod is mandatory for this. You will also need to use manual focus. Try beforehand to focus on something which is far enough away to guarantee that the fireworks will be within the depth of field. Infinity will likely work. But do not crank a zoom lens to the infinity stop, as most such lenses will focus past true infinity, and be blurry all through. Look for a distant light, house window, etc. if you can.
That's a very general rule, and will depend on a few things. Check a picture after taking, and either lower ISO or close aperture a little if the image is too bright or blown out, and open up or raise ISO if it's too faint. But generally if you get a good display of fireworks, especially if bursts overlap some, you'll get some overexposure of the brightest parts, and that's unavoidable.
Do not leave auto ISO on, because in the dark the meter will crank the ISO all the way up, causing the picture to be noisy and overexposed. The meter cannot understand fireworks.
Unfortunately the D3200 does not allow multiple exposures on the same frame, because one other way to do this is to shoot shorter exposures and then shoot subsequent ones over the same one.
If you do not have an infrared remote, which allows you to shoot in true time-exposure mode, one other option would be to set the shutter speed manually to some long exposure time. Try, say, 20 seconds, trip the shutter when you see a rocket going up, and see what happens. If you time it right, you'll get some hits. But there's also the likelihood that some rockets will be partially fired when the shutter closes. Yet another possibility would be to set it at a full 30 seconds, but keep a card handy. Open the shutter, and when you think it's had enough, cover the lens until the shutter stops (being careful not to bump it). Yet another possibility is to open the shutter, cover it, and remove the cover when bursts occur. Put the cover back, and remove it, as required during the 30 seconds that it's open.
It's a little late to do anything this year, but if you're not aware, the D3200, among other models, does not have a true "time" exposure setting, only "bulb," which holds the shutter open only when the button is pressed down. Even on a sturdy tripod this risks vibration, and is not ideal. But when you use the infrared remote release, the bulb setting becomes a proper time setting, in which the first button push opens the shutter, and the second closes it. This is just right for long exposures and highly recommended.
Here's one I got the other night, a bit on the quick and dirty side, when the neighbors across the road put on some fireworks. It's a long exposure about 130 seconds, F10, ISO 200, wide angle. This was with a D7100 using the infrared remote. Multiple rockets were fired in this shot. Note that there was very little ambient light here, and that if there is more light on the scene, the surroundings may lighten up, and any non-firework lights will likely blow out. This also was not a huge, commercial show. You will probably do better with exposures a good bit shorter, and it will depend mainly on how many bursts you want in an image.
PS...apologies for such a late posting. It occurred to me after doing so that anyone asking this question was probably out at the fireworks by the time it hit the page. Well, I hope you got some good shots anyway.
Comments
The last fireworks I shot, I used a time exposure of varying length, and got pretty good results at F10 and ISO 200. The lens was set fairly wide, but what focal length you use will depend, of course, on how far away things are.
A tripod is mandatory for this. You will also need to use manual focus. Try beforehand to focus on something which is far enough away to guarantee that the fireworks will be within the depth of field. Infinity will likely work. But do not crank a zoom lens to the infinity stop, as most such lenses will focus past true infinity, and be blurry all through. Look for a distant light, house window, etc. if you can.
That's a very general rule, and will depend on a few things. Check a picture after taking, and either lower ISO or close aperture a little if the image is too bright or blown out, and open up or raise ISO if it's too faint. But generally if you get a good display of fireworks, especially if bursts overlap some, you'll get some overexposure of the brightest parts, and that's unavoidable.
Do not leave auto ISO on, because in the dark the meter will crank the ISO all the way up, causing the picture to be noisy and overexposed. The meter cannot understand fireworks.
Unfortunately the D3200 does not allow multiple exposures on the same frame, because one other way to do this is to shoot shorter exposures and then shoot subsequent ones over the same one.
If you do not have an infrared remote, which allows you to shoot in true time-exposure mode, one other option would be to set the shutter speed manually to some long exposure time. Try, say, 20 seconds, trip the shutter when you see a rocket going up, and see what happens. If you time it right, you'll get some hits. But there's also the likelihood that some rockets will be partially fired when the shutter closes. Yet another possibility would be to set it at a full 30 seconds, but keep a card handy. Open the shutter, and when you think it's had enough, cover the lens until the shutter stops (being careful not to bump it). Yet another possibility is to open the shutter, cover it, and remove the cover when bursts occur. Put the cover back, and remove it, as required during the 30 seconds that it's open.
It's a little late to do anything this year, but if you're not aware, the D3200, among other models, does not have a true "time" exposure setting, only "bulb," which holds the shutter open only when the button is pressed down. Even on a sturdy tripod this risks vibration, and is not ideal. But when you use the infrared remote release, the bulb setting becomes a proper time setting, in which the first button push opens the shutter, and the second closes it. This is just right for long exposures and highly recommended.
Here's one I got the other night, a bit on the quick and dirty side, when the neighbors across the road put on some fireworks. It's a long exposure about 130 seconds, F10, ISO 200, wide angle. This was with a D7100 using the infrared remote. Multiple rockets were fired in this shot. Note that there was very little ambient light here, and that if there is more light on the scene, the surroundings may lighten up, and any non-firework lights will likely blow out. This also was not a huge, commercial show. You will probably do better with exposures a good bit shorter, and it will depend mainly on how many bursts you want in an image.
http://jmp.sh/v/IAuXsByMHTIEFuXK0ouh