Quote Originally Posted by Willie Jan View Post
Hi,
i am using a 120 rodenstock macro lens.
When using it at 3:1 i loose 6 stops of light.

Is there someone who did a test between using a closeup lens together with a macro and only using a macro lens? I would like to know if there is a quality drop when using a close up lens. At this moment i do not own a closeup lens, so I can't test it...
6 stops at 3x is a quite a lot. That lens must be a very asymmetric tele-construction.

Anyway,
Yes, while you don't lose light (as much) when putting close-up lenses on a lens to shorten its focal length, there is a price to pay for that. Using close-up lenses (whether on a regular or macro lens) produces a significant drop in quality.