10mm vs 18mm

Found few photos related to the subject for my own reference. Credit goes to the owner of the original images.

18mm, approx 72 degree angle of view



10mm, approx. 110 degree angle of viewFrom: wilful disbelief's blog

Useful photo from shutterasia, applicable for canon cropped sensor (1.6x), but at least give you some rough idea on how it'll look like on Nikon DX (1.5x)

Found a link for focal length comparison from Tamron.
For distortion between 10mm to 24mm from Photozone website.
Discussion on focal length vs viewing angle can be found here.

Also interesting discussion in ShutterAsia forum related to ultra wide angle. According to the OP, he prefer the sigma rather the more expensive Nikon. The only complaint he has so far is the followings:

• Stupid coating which is liable to peel off
• Stupid side-pinch lens cap which can't be used with the lenscap on (I changed mine for center-pinch Nikon cap - which is good)
• Non constant f/4 aperture - but as I explained above in reality I don't find this a limitation

Saving up for an ultra wide angle before my London trip end of next month.