The Nikon 180mm 2.8 is one of Nikon's sharpest lenses. I've owned each version since it became available in the 1970s. The 105mm is legendary also.

It's good to see someone contemplating purchasing excellent fixed focal length lenses instead of those do everything (but nothing excellently) zooms.

Personally I wouldn't consider anything other than Nikon lenses.

Hi Larry
Thank you I do a lot of natur photos water falls,flowers and I also shoot car racing at Lime Rock Park in Ct.
I have a Nikon 80mm-300mm but it is a kit lens tho it is a nikon. I also hope to have a D200 by the end of the summer.
P.S I have photos in the gallerys under jrhoulihan
Thanks for your help Jim

The Sigma 105 is a great lens, very sharp. I don't know about the 180mm. I guess it all depends on what you are going to do with your images. Unless you are selling them professionally or doing huge blowups you will probably not see a diffrence between a good 3rd party lens and a nikon.

If your prints are no larger than 24" on the long side you should see no diffrence. If us amature/advanced amature and semi pro photographers would concentrate more on composition, focus, and lighting rather than equipment we would get better images. Modern glass is so close to perfect unless images are examined at extremly high resolution and under labratory conditions you would be hard put to tell the diffrence.