Selecting appropriate reverse ring for your camera & lens ( For all dslr )  

Everyone new to this reversing technique will have a confusion about "how can i buy appropriate ring for my lens and camera , how can i know its measurements , how do i search for it ".

The answer is very simple , we only need to know how much our lens filter size is !

How do i find out my lens filter size or diameter?

Almost all lens filter diameter will be mentioned behind its top lens cap.(as in this below picture,diameter is mentioned as 72 mm) That means your lens filter size is 72mm 

In some brands of lenses or if someone lose their lens cap and is not able to figure out how much their lens filter size is , refer image below.This is top view of a sony lens and diameter or filter size of this lens is depicted as "72 mm" with a circle and a slash on it.

So when you have determined filter size of your lens , what you have to do next is that.

You have to search in google like this (as my lens is 18-55 mm and have a filter size of

"52 mm" also i am a Nikon user) "52 mm reverse ring or adapter for Nikon".

From the google results check various products and purchase the one with good reviews and comments.