Which lens should I go with?

[allahkaram]

Nikon 18mm f3.5 ais lens
http://www.kenrockwell.com/nikon/18f35ais.htm

or

Nikon 20mm f4 ai lens
http://www.kenrockwell.com/nikon/20f4.htm

I definitely want wider lens but my question is how big of a difference will I notice between the two?
I don't like vignetting but I love the distortion so which lens is more prone to give me that?

HELP!!!

 

[pmark23]

I'm not familiar with those lenses, but I have a Tamron 17-35 f2.8-4 which is surprisingly good for it's low cost.

I had it stopped down to f4 to optimize the sharpness, and it was still bright enough that I didn't need too much light. Good corner-corner sharpness, and even exposure over the entire lens. I believe Ken has a review on his site.

 

[rambangbang]

Nikon 18mm. F3.5 its ok and its wider. But 4.0 is not enough light.

 

[Steve Laramie]

both are really crappy for light. I would consider waiting until your budget can support a 2.8. If you cant wait then go with the 3.5.

 

[JamieF]

3.5 all day