In my opinion, the right number is 6.
- 105/2.5 "silver nose", the early sonnar version with 9-bladed aperture diaphragm.
- 105/2.5 AI, gauss construction with the larger rear element.
- 105/1.8 AIS
- 105/2.8 AIS Micro Nikkor
- 105/4 AI or AI'd Micro Nikkor
- 105/2 DC
I have had some more, but sold them off as they didn't do anything my 6 don't. I used to have both versions of the AF Micro Nikkor but sold them as I value MF feel too high when shooting closeups. The 6-bladed sonnar has really harsh bokeh. I never liked the AIS 2.5 because of the shorter focus throw and flimsy and short hood.
The 1.8 does not do portraits as nice as the silver nose and is not quite as good for landscapes as the AI 2.5, but since it does both better than the "wrong" 2.5 for the job I use it a lot.
The 2.8 AIS gets a bit shorter in focal length when focusing close, which I don't like, but it is faster, which I do like. The 4 on the other hand gives more working distance when using larger magnifications.
The DC is a joy to use in a studio setting, but the older manual cousins are easier to use well in the field. The effects of the DC can't quite be reached in post, even if you can do something like it...
What are your favourite 105- lenses? Discuss!
/Peter