thanks for the thoughtful posts and interesting discussion.
Looking back it seems that the original post was bit naive to ignore user requirements and expectations, as well as weather limitations and cost. However, the general thrust still seems to be backed up by the later posts - there really can be no prescriptive requirement on the length of exposures, for a whole gaggle of reasons. I wasn't trying to knock any systems, just to point out how radically different they could be in sensitivity.
Must say that I personally enjoy watching subs as they come in - nice to be part of the acquisition process. I can see how automation would allow many more/dimmer targets to be imaged though - I guess it all depends on what each of us wants from the hobby
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