I did some experimenting with lens hoods. From my other camcorders and digital SLR's, I do have many lens hoods and filters.
Before buying a 41.5, i wanted to make sure that I could use a lens hood with the TM90. I tried some of my rectangular wide angle hoods, just holding them at the lens, in the position that they would be, if mounted. I actually found a slightly larger one to fit over the lens barrel.
But, they all vignetted on the right side, at full wide angle. The TM90 is a close call on len thread design. As Romony said, a 58mm "may" work, but its too large for the camera. I have a 58 and 62 wide lens hood, but they get in the way. I could probably make something work, but it would be too large and bulky for the camera. It would also get in the way, when mounting on tripod.
I don't see that I would get any lens hood to work properly, so i will skip the 41.5 adaptor. I don't need filters, as some of you may.