Correct Resistor for maximum light output on Red LED

encryptor:
It says on the front of the package 5 volt, 30mA, 300mcd. Here is the link to this LED. I see in the reviews someone points out this is not really a 5V LED and results show to use 3.5V forward (supply) voltage.

http://www.radioshack.com/product/index.jsp?productId=2102850

As we suspected. I would never trust Radio Shacks 'specifications' on something like this. It appears to be a bog standard blue LED and as such needs to have an external current limiting resistor.

Lefty