Author Topic: micro-nikkor 105mm f/4 Ai-S!!!  (Read 1003 times)

Erik Lund

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Re: micro-nikkor 105mm f/4 Ai-S!!!
« Reply #30 on: March 16, 2021, 08:53:52 »
The AIS 105/2.8 micro does have floating elements, the basic structure is a double-gauss 75mm f/2 lens with close range correction applied between the front and rear groups, and a 1.4x teleconverter fixed at the rear, so there are three groups of lenses which should prove a higher level of correction at all distances. Surely the Nikon designers would have wanted their new f/2.8 macro to be superior to the older model over the entire focus range.   

This is interesting Roland where did you get this information from? I always thought the last four elements look like a tele-converter. So as the front elements move forward, they magnify the image and the focal length increases instead of decreasing as most CRC systems do. Regards Gerry


New is not always better regrading all points of performance, clearly this is the case here for 'usable working distance' in front of the lens and focal length shortening (focus) breathing which is the case here compared to the 105mm f/4
This trade off of for introducing floating elements for close up sharpness is obvious.
Sure they wanted the 105mm f/2.8 Ais to be 'better' than the privies versions and they succeeded in most aspects for all use cases ;) 

Design choices; The 70-180mm Micro Nikkor is also a great example, so much research and development went into that design.
Erik Lund