This gives you a very flat FOV with the SW ed100 when used with a canon dslr and acts as a .85 reducer giving you f7.65.
Requires a wide T-ring which I will throw in for $10.
OPT have this at $264.89, for sale at $175.00 plus postage. In Very good condition.
PM please if interested
http://www.optcorp.com/sw-s20201-red...ro-100-ed.html
Cheers