You asked
What are the alternatives to the leica elmarit tl 18mm f 2 8 asph?
The site doesn't list any other lenses as alternatives to the Leica Elmarit-TL 18mm f/2.8 ASPH. That page only shows which cameras it fits, so I can't name substitutes from it without guessing.
If you want a similar wide prime, start with the focal length converter. It shows how a lens's framing and depth of field change with your sensor, so you can compare other wide lenses on your camera. The lenses guide explains what the f-number means for light and background blur, which helps when you're comparing primes.
Written by Claude from this site's pages.