Hundreds of every day photographers, either originally from early portrait studios or new "operators" quickly learning the craft, followed the troops during the war. These "tintypists" would set up their portrait galleries or studios near the troops. A quick dollar would be had by the photographer as he would attract many a soldier to have his likeness rendered. More often than not, these photographers would record studio style images using simple backdrops and props on ferrotype or "tintype" plates.
Ferrotype plates have many advantages: They are much more durable than glass plates, and could easily be mailed home in letters or kept fairly safe among the personal effects of a soldier on the march. Ferrotype plates could also be sleeved into paper mattes, instead of more expensive "Union" photo cases which more often were used for ambrotypes (positive images on clear, black or ruby glass). Although a great many ferrotypes were cased in Union cases as well.

The ferrotype plate also allowed for quick turnaround from the photographer to the soldier. Thus many images could be made in a short length of time, and be had by the troops for a reasonable amount of money.
There is no tin in original tintypes, the images were originally made on sheets of iron. I have heard two reasons why the name tintype is used to describe the process. One is that the images were cheaper than other more expensive photographic processes and the images were referred to as "cheap as tin." Another possible reason for the name derives from the tin snips that were used to cut the plates apart.
My impression closely resembles those early itinerant "tintypist" photographers. My camp is styled in a manner with a simple back drop and minimal props, so that I can mimic these early photographer's and their style of photography, creating images that resemble those that were taken during the conflict.
I also stray from the itinerant photographer, and make "Brady-like" camp life scenes when I can. I photograph with glass plates and print multiple copies when I arrive back at my home studio. Mostly I try and preserve the itinerant photographer, to continue to keep the occupation alive through reenactments and my impression.