Taking Portaits help

Hi guys, I have a Sigma 18-200mm, and take alot of portraits. its 50:50 portaits:landscapes

i've found anything below 35mm creates too much barrel distortion with the person's face

what the best focal length to take portraits with that lens?

and should i pony up for a 50mm 1.4? they're about $300AUD, which is alot of money

whats the best lens for taking portraits with? i would often be indoors in low light situations. i'm not even going to consider an external flash for the time being. although i know i should get one eventually for the portrait work.

cheers fellas

PS. do you guys have any tips for taking portraits? without a full on studio

Hi,
Have a look at the threads in the lenses forum. There are various discussions and opinions on the 50s, 70DA, 77Ltd, 85 etc etc.

Kim