Before digital, with film, there was a thing called reciprocity, that, generally, means that the length of exposure increases exponentially as the exposures get longer, unlike digital which makes long exposures very easy including my specialty moonlight, since, amongst other things, digital has no reciprocity. This is five years of batteries that I had to use in order to capture long exposures by both moonlight and no light in urban areas. I also made entire books shot with only moonlight in the American badlands, the Appalachians and even abandoned industry and steel mills when there was absolutely no artificial light left.
This is a five year accumulation of dead batteries which could really add up as an expense during monnlit nights and many nights out in the Meadowlands and industry in the cities.