Last week I posted this question and got good feed... (
ETTR buys less noisy shadows at the price of possibly blown highlights. In the sample photos
the OP posted, the hightlights are snow fields, which has almost no detail anyway. This is almost
certain to make ETTR look good.
ETTR is a work-around for noisy digital sensors. Night photography involves long exposures
and/or cranking up the ISO. Either way, you get more noise than normal. So on the face of it,
a bit of overexposure is a good idea for night photography.
In long exposures, digital sensors don't have reciprocity failure like film does, but they accumulate
chroma noise. Also turning up the ISO always increases noise. Over-exposure can help improve the
image-to-noise ratio in shadows, which helps to justify risking a few blown highlights.
The real solution would be to have less noisy sensors. This is achieved in astronomical applications
by supercooling the sensor. That's not practical for everyday photography, but there has been some
improvement, with newer sensors being -- on the whole -- less noisy than old ones. If this trend continues,
we should less and less about ETTR for well lit situations.
Any "rule" for exposure that doesn't take the photographer's intentions (for how he wants the subject to
look) into account is just another form of automatic exposure. It will look how it looks, you may like it,
you may not.
I don't like colored speckles, so I use film and long exposures for night photography (and have to deal with
reciprocity failure). For a given brand/type/speed film, the manufacturer usually provides a curve of that
film's reciprocity failure. This graph can be used to estimate normal exposure. If a mathematical function
is fitted to the curve, then you can even have an exposure calculator for that film. If done correctly, the
resulting negative is no better or worse than one made in normal light.
Photography is about the final image. Camera's can't read minds, so the photographer has to play a role.
Only he knows what the objects in the scene are and how they generally look in real life. Only he knows
the image he is trying to create.
Rules can be helpful, but there are always multiple considerations. The "shoot lots and cull" approach
often amounts to picking the best of a bad lot.
So the answer is yes, ETTR is a helpful rule in digital night photography, but it's no substitute for visualization--
and choosing the exposure that produces the image you
want. It's just another consideration: when
shooting with a noisy sensor, over-expose a bit.