Mark, I tried to get some long exposure shots at the ocean last night, triopod and all, but came up woefully inadequate (screen was black). I'm sure I was setting the exposure incorrectly, but I'm not sure why, will have to check my owner's manual.
Your meter might have been fooled by light entering from the viewfinder. Most of the time, you don't have to worry about light from the viewfinder. During the metering, your eye is covering it so not much light gets in. During the exposure, the mirror is flipped up so no light gets in. The challenge is when you compose, move away from your camera, and then use a remote shutter release to trigger the shot. If you are using a mode other than Manual, your camera will check the light level just before opening the shutter. When it does that, it might see light coming in from the viewfinder and assume that the scene is brighter than it really is.
There are several ways to deal with this. The most straightforward is to meter in manual, setting the exposure while looking through the viewfinder. If you don't want to do that, you can cover your viewfinder. Some camera straps have a little fitting designed to slip over your viewfinder. My viewfinder has a little lever that you can push down to cover the viewfinder. You can also just hold your hand over it (be careful not to bump the camera).
This usually doesn't cause black pictures. It usually just causes a mysterious underexposing. If they are really back (and you didn't have a bright light shining into your viewfinder), it is probably something else.
In the old film days, you have to worry about all of that and reciprocity failure. Uusually, if you reduce the amount of light by half, you double your exposure time and everything is fine. With film, for exposures longer than a second or two, that doesn't quite work. You actually needed a longer shutter speed than you would expect based on standard metering. I'm glad those days are gone (at least for me).
Anyway, the sun had set so I followed the color to a different, nearby location and was able get these (handheld). I wished I'd composed them a little differently, but hey, live and learn. I liked the color, at least. I might try again tonight. Any thoughts are welcome.
Wow. Those are lovely. On the second one, I'd try cropping into more of a panoramic shot to eliminate the really dark sections. Similar to what I did with this shot from my Canada trip: