I wouldn't use this as a guide on how to organize your business (as a sole proprietor, LLC, corp, etc). This is heavily state dependent. My state (Washington) doesn't recognize S-Corps (we have no income tax anyway) as it's an IRS distinction. The IRS doesn't recognize LLC and will default you into a sole proprietorship or partnership, depending on the number of owners. You can elect to go C- or S-corp with the IRS after the fact.

If you make all your money from your photography business and it's a good enough income, you'll probably want an LLC (if your state allows this) and file taxes as an S-corp. Some states allow you to form as an S-corp, so depending on the legal description of your specific state you form your company, that might be a better route (or the same thing in meaning, but the only difference is the name). If you have investors, they may require you form as a corporation, but file taxes as an s-corp (or c-corp).

If you don't make much money from photography, probably an LLC and file as a sole proprietor (the amount of extra taxes you pay (if any) is negated by the amount of accounting required to pay yourself a salary). Also there may be issues of drawing business funds as personal funds that can pierce the liability shield of an LLC, making yourself personally liable for actions of the company.

In short, if you don't know what you're doing, talk to a lawyer. If you do know what you're doing, ignore everything I said--you don't need this info.