The effects a tube has on a particular lens differs from lens to lens. There's no way to predict what effect it will have on a lens, and even if there was, the firmware that contained the correction would be as large as the firmware that contained the correction for all lenses without the tube.
- The lens is the thing.
- 'Full Frame' is the new 'Medium Format'.
- "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.