If you find yourself needing to go over 30 seconds, not likely but possible, you should know that the inexpensive IR remote which works nicely with the D3200 is the only way to get a true time exposure with hands off. When you set the shutter to "bulb" in S or M modes, the first push of the remote button opens the shutter and leaves it open, and the second shuts it again.
Because the kit zooms will focus past infinity, you can't just twist and forget. You must try to find a very distant object, a tree on the horizon or a celestial body you can see clearly, and focus on that. It's better to be a little short of infinity than past it.
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Here's one I came across that looks as if it's aimed at about the right equipment: http://www.astropix.com/HTML/I_ASTROP/QUICK.HTM
If you find yourself needing to go over 30 seconds, not likely but possible, you should know that the inexpensive IR remote which works nicely with the D3200 is the only way to get a true time exposure with hands off. When you set the shutter to "bulb" in S or M modes, the first push of the remote button opens the shutter and leaves it open, and the second shuts it again.
Because the kit zooms will focus past infinity, you can't just twist and forget. You must try to find a very distant object, a tree on the horizon or a celestial body you can see clearly, and focus on that. It's better to be a little short of infinity than past it.