Hi,
Have a look here:
http://www.schneideroptics.com/Ecommerce/CatalogItemDetail.aspx?CID=1072&IID=873
Have a look at the samples.
When you switch to 16:9 with your vx2100, you simply apply a "mask"
to the video your camera is recording. You lose a lot of video information.
It is a "false" 16:9
When using the Century optics lens you get
real 16:9. Your recorded image is much wider than what you would record with the "false" 16:9 that your vx2100 gives you.
I hope it answers your question