Sorry Fahim, I just checked and you are right. I used the Bintel extension (slightly shorter than the Mogg one which I don't have
) to achieve about 0.45 reduction. However, I do know it's 0.45x, as I did an astrometric test on an image of the Jewel box using AIP4WIN V2 specifically to find out the reduced focal length. Native 2000 focal lenght reduced to 917mm.
As you will notice on the bintel site, their FR is only 0.7 without the extension. Their extension measure 25mm when fully threaded, whereas the mogg one is considerably longer (see image) to be used with a native 0.6 reduction. The degree of focal reduction depends on the lens as well as the distance the lens is from you imaging plane
Sorry about the confusion.