I tend towards darker pictures when it comes to dusk/dawn shots. Of these two, again I tend to the darker. But is the lighter photo here better in terms of the exposure?
I am trying to capture the most stunning contrast of colors of the sunset seen below. I am worried that the darker one eliminates too much character of the rest of the sky.
Is that true? Or am I right in thinking the darker one is more dramatic, more contrasted.
Which is better is a personal preference.
In terms of exposure this would be an example of a scene I'd consider using the Expose To The Right method (which I generally consider overused by people). After you use ETTR you would need to adjust the final image in post processing (like Photoshop, GIMP, LightZone, DarkTable,, RawTherapee etc.) to choose a pleasing effect.
Doing this means you retain the flexibility to adjust exposure to taste in post processing and don't have to worry about it at shot time.
I'd use ETTR here because it would let me get the exposure of a static scene with minimal noise and maximum dynamic range. In general photography using ETTR can compromise your ability to choose more important parameters (like shutter speed), but for this type of scene it's usable.
I would strongly recommend using RAW when shooting ETTR.
The exposure is too bright when you have overexposed: Lost details due to pixels saturating and there is no more difference between pixels recording parts of the scene which were of different brightness.
As long as you do not reach the point of over-exposure, there are technical reasons that make brighter exposures better. In short, this preserves more details an nuances in the image. See my answer here describing Expose-to-the-Right (ETTR). Now that question was about image quality, not artistic result.
When you produce a darker exposure, it may convey more the experience you had when taking the photo. Darker exposures also make colors appear more saturated which is what you noticed in your sample photos. Of course, a darker exposure means that the relatively darker parts of the image will lose details. Due to the way sensors work, there are fewer nuances in lower stops.
The bottom line is that a brighter exposure without any overexposure is better from a technical point of view while a darker one may deliver a more representative or evocative image. Finally, one does not preclude the other. One can shoot a brighter exposure and use image manipulation to produce a dark image from it. Those who shoot RAW do this all the time since that data is linear and tends to look very flat without a suitable tone or contrast curve.
What you really need is to make and HDR photo. Yes, the area at the horizon is perfectly exposed, but the area at the top of the photo is too dark and loosing detail. Take two photos: one exposed for the sunset and a brighter one that is exposed for the dark clouds. Layer these two photos together to give a more even look throughout the photo. Then you will have more detail in the darker region which will allow you to edit more and add more contrast.
Disclamer my advice is based purely on my subjective opinion of what I like in a sunset photo, and the experiences in solving a similar problem I had in my sunset photos.
For a more dramatic sunset image out of the two: the darker one is more dramatic, you can also warm up the color temperature for more brilliant red, and maybe add some Clarity/Contrast. If you're serious about getting really good sunset photos, exposing to the right and more nuanced post-processing may be needed (read on).
I think that there are two separate aspects to exposure that have been conflated:
1) exposing in camera
Regarding in camera exposure, if you aim to post-process your images you should almost always try to expose to the right in digital photography (see StephanG or Itai's answers) and use RAW for high contrast scenes (like sunsets), because this will give you the most post-processing flexibility. If you do not want to post-process your sunset images, than what I usually do is underexpose by about 1.5-2.5 stops (this increases perceived saturation and stops highlights from overly blowing out) and setting white balance to cloudy or shade- this will give you a more intense red instead of the quite pale yellow-orange-blue sky. The white balance in sunset photos, usually gives more of a dramatic effect than the exposure.
2) "exposure" adjustment in an image processing software
If you are only going to play around with the exposure adjustment, it's probably OK just to expose in camera and skip this step. If, however, you want a more polished look: visible details in silhouettes/shadows, more "dramatic" contrast, selective color saturation, increased local or micro-contrast etc. you should expose to the right, shoot raw and use some kind of post processing software. Learning a couple post processing tools (adjusting hue/saturation/value/contrast or better: manipulating color curves) and strategies (for example learning about the Ansel Adam's zone system, and/or Munsell Color System) will allow you to achieve the look you are after more easily and consistently, but the latter can be a bit time intensive.
General tips for sunset photography Sunset colors are more brilliant when there are large particles in the air (in high humidity, after a storm, during high air pollution). Capturing the "second sunset" (around 10-15 minutes after the regular sunset) can give more even illumination to the sky (this reduces blown out highlights, and makes the whole sky look wonderfully colorful), and gives more color to the clouds. High altitude clouds can give a more dramatic effect especially when patterned, because of the way they scatter and reflect the sunlight.
