What lens would you suggest, we need to film out to 250 yards so we need at least a 20 optical. So what would you recommend for the HDR-fx1

When you say "20x" it isn't necessarily very informative, because that number is relative to the widest lens focal length. But just on the basis of what you've said, 20 x 1.6 = 19.2x, so a 1.6x teleconverter will get you pretty close to 20x. I am using the Century Optics 1.6x teleconverter and have been very happy with it. Not cheap though, as well as big and heavy.

http://www.bhphotovideo.com/c/product/361301-REG/Century_Precision_Optics_0VS_16TC_HDS_1_6x_Telephoto_Converter_Lens.html

They also make a 2x converter, but that's even bigger, heavier and more expensive :-)