do I need an extension tube

[judenoypi]

HI guys, just want some advice,I have a canon EF 100mm F2.8L IS USM, do I need an extension tube inorder to close really to the subject,and do you think its not gonna affect the sharpnesss of the picture if i use it.Thanks for your advice

[inkista]

Only if the 100 isn't getting you close enough. It won't affect sharpness: an extension tube is just a hollow tube without any glass elements, but it will affect the amount of light coming in and your ability to focus to infinity.

[judenoypi]

thanks appreciate it