What is this "widget"?

[reagan]

I recently purchased a Canon Lens mount Converter B. With it came a little black widget that the seller says is part of the unit.

See attached photo. Can someone tell me what the little thing is and what it's used for?

Thanks for your help.

 

[harry01562]

Re: What is this "widget"

Re: What is this "widget"

Your pic was a bit small, but it appears you got a bonus with the converter. That little plastic thingy is used when reversing a Canon FD lens to use on macro shots. It allows the lens to stop down, where normally it will stay wide open. Ive seen them sell on eBay for $25+, based on being scarce.
It has nothing to do with the converter, but don't tell the seller that. 🙂
Harry