When is a medium format camera useful?

Medium format used to be the standard for fashion work.

Medium format is still mainly a film domain, and the larger negative provides enhanced sharpness and detail compared with 35mm. It was used whenever greater resolution was required by the final product - be it magazine, billboard, or even traditional portraiture. Today, digital resolution is almost as good (if not better) than medium format.

It is definitely not needed for billboards. If you ever go up to a billboard closely, the dots are the size of dimes. You can do that with a little 8 MP camera.

The only time I see it used much is for fashion photography. Even then it is starting to be replaced by 35mm digital.

Most magazines don't care about the camera format. Nat Geo requires a minimum resolution of 8MP for a two page spread. Since all cameras are 12 and up, and camera meets these requirements. I just shot an assignment for Outside using a small point and shoot.

It's essential for billboard work. Some magazines also use this format.

Most glossy magazines and adverts use this format.

This format is particularly used for product photography. For example, an ice cold bottle of Becks with drops of condensation running down it. Or Apple's latest catalogue.