50 mm 1.8 lens

[pasknucklehead]

Hi my new friends,
I know that everyone says that a good portrait lens is at least 80-90mm somewhere in that order. I want to really do a close portrait and want to really make the subject stand out with a really blurry background. I have an 18-55, 55-200 and a prime of 50 1.8 lens. I know that typically the prime lens are sharper, so is there a way to get my background blurred with the 50 lens and what is the benefit of having to use a longer lens?
Also, I took some photos the other day of a horse, I actually think I posted it on here somewhere. But anyway, I am sooooooo used to using film and now transferring over to digital is really making me think. I wanted to get the horse blown up to 11x14 but I was told by my lab that I would lose the ears. Can someone explain how much a digital image is different than say a film image. I know that with film, I would have gotten all the horse in the enlargement, I;m fairly sure of that, so I was really disappointed that I couldn't get it done in the size I wanted.
Thanks guys,
DC

[jerryph]

The fast answer is that yes you can do it with the 50mm... you can also likely do it with all your lenses to some degree if you understand how. Understanding DOF or Depth of Field is one of the topics covered in the course offered here. Understanding it permits you to use small (numerically large apertures) and still blur either the foreground, background or both.

An example, this picture was taken at F/7, yet I still clearly blurred the foreground and the background:

http://farm3.static.flickr.com/2267/2341040381_8c25508826.jpg

The EXIF is included HERE (http://flickr.com/photos/jerryph/2341040381/meta/in/set-72157604136892371) as proof.

The benefits of using a longer lens is less distortion. Effects like "chipmunk cheeks" or looking like "the camera added 10-15 pounds" are reduced when you use focal lengths between 70 and 200mm.

Concerning the pic, I would need to see it if it could be cropped to a 11 X 14... but if it cannot, what is stopping you from framing it to a ratio that permits the complete horse from being seen?