shutter speed slower than 30 sec.

[don_narayan]

I have seen some great photos of stars and the shutter speed is often 2-4 hours. But seeing what cameras they are using, the minimum shutter speed is listed as 30sec. How can you keep the shutter open for so long?

[thien]

You need to use what normally called the "bulb mode" which you need to pressed once for the shutter to open and a second time to close.