The writer of the film adaption of Fifty Shades of Grey says she's aiming for an NC-17 rating.

Kelly Marcel, the woman who's writing the script for the first installment, says, quote, "It’s going to be raunchy.  We are 100% going there."

Not every sex scene can be represented in a 90-minute movie.  Marcel says, quote, "We did go through and decide which are our favorites and which are not.  Most of them are in there, but I can’t say more than that."

Here's something to note: while she may be writing an NC-17 script that doesn't mean an NC-17 movie will result from it.  The studio will decide how far the movie goes.

And as you can probably guess, it's hard to get NC-17 movies into theaters.  And if you don't get "Fifty Shades" into theaters, you're saying goodbye to massive box office revenue.  What studio is going to do that?