On Sun, 15 Jul 2001 18:34:08 -0700 (PDT), bigrocketman3@webtv.net (Steve McDonald) wrote:

[Lotsa good advice deleted - read above...]
> Ever have difficulty getting a lens hood unscrewed? Instead of
>grabbing it around the outside, squeezing inward and attempting to turn
>it, place a finger on the inside of the rim and a thumb on the outside.
>When you turn it then, there is neutral pressure against the threads and
>the hood will often come off easily.
>Pressure placed inward around the rim will bind the threads against the
>inside and keep them from freely turning.

This works well for nested step-up/step-down rings, also.
The parts are too thin to get a good, even grip on them
around the edges, but using your method, there is usually
success.