Wide angle lens comparison between four lens:

Pentax SMC DA 35mm F2.8 limited macro
Pentax SMC-DA 15mm F4 ED AL Limited
Pentax SMC DA 18-135mm 3.5-5.6 ED AL (IF) DC WR
Bower 14mm f/2.8 ED AS IF UMC manual focus,

Photos were taken in RAW, converted to JPG with no sharping or other processing, other than adding text.

131216-8122_DA_35mm-F2.8-limited-macro_

131216-8122_DA_35mm-F2.8-limited-macro_

131216-8124_DA_15mm_F4_ED_AL_Limited t

131216-8124_DA_15mm_F4_ED_AL_Limited   t

131216-8126_DA_15mm_F4_ED_AL_Limited_F6-7 _

131216-8126_DA_15mm_F4_ED_AL_Limited_F6-7  _

131216-8128_DA_18-135mm_3.5-5.6_ED_AL_(IF)_DC_WR

131216-8128_DA_18-135mm_3.5-5.6_ED_AL_(IF)_DC_WR

131216-8130_36mm_DA_18-135mm_3.5-5.6_ED_AL_(IF)_DC_WR

131216-8130_36mm_DA_18-135mm_3.5-5.6_ED_AL_(IF)_DC_WR

131216-8131_Bower_14mm_f2.8 _ED_AS_IF_UMC

131216-8131_Bower_14mm_f2.8 _ED_AS_IF_UMC

131216-8133_Bower_14mm_f2.8 _ED_AS_IF_UMC

131216-8133_Bower_14mm_f2.8 _ED_AS_IF_UMC