Question about Raynox DCR-250, Macro / Close-up Front lens

Yes, because the Sony 90mm has a filter diameter of 62mm, which means it falls between 52 and 67mm.
The longer the focal length, the greater the effect of Raynox; it magnifies by about 2.5x with a 100mm lens.
Here's a magnification calculator: extreme-macro.co.uk/raynox-adapter-techniques/
With the Sony 90mm, min. focus 0.28m, this gives a magnification of 2.44 ( 2.44 times more than the

1:1 ratio of the lens)

Yes, it works fine; you are just extremely close to the subjects you want to photograph. The Raynox fits many lenses and cameras and is an affordable tool for extreme macro.

Yes, because the Sony 90mm has a filter diameter of 62mm, which means it falls between 52 and 67mm.
The longer the focal length, the greater the effect of Raynox, which magnifies by around 2.5x with a 100mm lens.
Here's a magnification calculator: http://extreme-macro.co.uk/raynox-ada...
With the Sony 90mm, min. focus 0.28m, this gives a magnification of 2.44 (2.44 times greater than the 1:1 ratio of the lens).