Surprisingly for the price I found, however, that both sides metal bayonet. But that does not conceal that the supporting parts cheaper plastic and should therefore be supported in use with more expensive lenses ALWAYS!
However, the rings complement each other perfectly with the Canon EF 50mm f1.8 - which is usually to be had for about 100.
The optical quality of the fixed focal length and the rather large aperture diaphragm plays the loss, one has Naturally with intermediate rings, opposed.
By the way perspective is not worth really to combine the rings with a zoom lens, since the zoom function is often be harmful to by the greater distance from the sensor plane and then really only the sharpness level shifting (I got the rings with my 70-200mm zoom tested and could not "Zooming". The image area remained virtually the same, but I was able to continue at 200mm from the object are 70mm as in, for example.
Screwing becomes somewhat hakelig, but also depends on the respective lens.
So for beginners and adventurous the intermediate rings are easier to handle than reversing adapter. Autofocus is one in Macro Photography of hand usually disable (rather Focus set firmly and then focusing by shifting body) but the iris is worth gold!
Stacks are all three extension tubes and combines them with a 50mm prime lens, you get an impressive magnification.
Another advantage: If you manage then at some point a macro lens on, you can also combine this with the intermediate rings in order to obtain an even higher magnification.
