I think the economics are actually a wash. Considering that digital sensors have a life. Like hard disks all sensors fail. I have film cameras that I still use that are over 40 years old. How many people will be using their digital cameras that long and what is the expected lifetime of a digital camera, five years? Three? Actually the life cycle of new DSLRs is about 18 months. Then, the pressure starts to upgrade to the better new camera long before the "old" camera wears out. Newer DSLRs take better pictures. With film cameras you can put the latest film in the camera to get pictures as good as any new camera will take. So, you have to compare the recurring cost of replacing your equipment with digital. That's why I think it's a wash.

People take more pictures they never use on digital. That actually makes it harder to find the photos that really matter. Digital makes it tempting for folks to shoot like fools and come back with little to show for it. The cost of film actually encourages people to think before they shoot. Also, many people who are not serious photographers often do not have protocols to backup and migrate their images to newer media. Thus, when a hard drive crashes the whole archive is often lost. A shoe box, on the other hand, can preserve negatives and prints a long, long time.

Cost per exposure digital is cheaper. You almost capture every second of your vacation for no materials cost. In fact you may be able to shoot eight frames a second. Now, let's talk about cost per picture that matters. People are actually printing less and leaving more images, garbage and good locked away on non tangible media. My parents had photo albums that were family treasures and movies we all knew by heart. Making a million copies of digital images that are forgotten in a month is hardly a value in my book. In my opinion for most folks digital imagery has gotten so cheap as to be perceived by most as being worthless. What's the value of photos that are not looked at, digital or analog?

I used to collect train photographs of every locomotive Southern Pacific owned by number. My primary responsibility was to make pictures that pleased me, even though they would put others to sleep. To calculate the environmental impact of digital images you have to calculate the impact of all the storage devices over the years the images are stored on, all the energy used and consumed storing, updating, migrating and editing the images vs. the shoe box my dad's black and white negatives sat in for 40 years.

~Steve