davidstorm wrote:
I have the Pentax 100WR and used to own the Sigma 105 DG EX. I sold the Sigma because I didn't need two macro lenses. However, it all depends on what you intend to use the lens for, is it just for macro work or do you intend other uses? The reason I ask is because the Sigma has a bit of an ace up its sleeve.

It is possibly the best portrait lens I have ever used, much better than the Pentax for this type of work. It has a sublime way of rendering skin tones and also has lovely bokeh. Another reason for selling it was my acquisition of a Pentax DA*50-135, also a superb portrait lens, but I think the Sigma is better, albeit fixed focal length.

For macro work, the Pentax is definitely the better lens, it is noticeably sharper and also being smaller / lighter is easier to handle when not using a camera support. The Pentax also has better build quality I think.

It may help if a few of us post images on the thread taken with each lens? Here are a few:

Sigma 105 Macro, this one with extremely shallow DOF due to extension tubes and wide aperture:





Sigma Macro:





Sigma Portrait:





Pentax Macro:





Pentax Macro:




Regards
David

Chrism8 wrote:
The Pentax 100mm WR is a cracking lens, quite small as well, good for portraits as well being F2.8 and on a PK crop camera is effectively 150mm

Mike-P wrote:
I have had them all and they are all good, to be honest I have never come across a bad macro lens.

I kept the Pentax in the end purely because it's made by Pentax and it's a WR lens but I also have a old manual focus Vivitar S1 105mm f2.5 .