First, Mongo has not noticed a great deal of difference between the two converters - although , it may depend upon the lens you use it with.
Secondly, the two converters are different lengths (the III version being shorter than the II). In theory, you would have to transplant the version III optics together as a combined group with perfectly exact distance from element to element as in the version III itself. Even if this were possible, you then have to try and get the rear element of the converter to be in a position ( in its new body) from the sensor that is exactly equal to the distance it would been in its original casing from the sensor AND at the same time, have the front element of the transplanted elements group the same distance from the rear element of any lens that would be fitted to that which it would have been in the original series III converter. Mongo cannot see how this is practicably possible becuase the body length of the converters is quite different. Therefore , Mongo thinks it is not technically possible and maintain the ability to focus the lens at all distances to the subject.
Mongo would love to know what NG's lens doctor thinks about this.
