This is a continuation of the series started at DPreview.com.
I will copy across all the messages from there so that we do not lose information if DPreview.com forums get deleted. But here are the original threads:
www.dpreview.com/forums/post/66804601 - Part 8
www.dpreview.com/forums/post/66553339 - Part 7
www.dpreview.com/forums/post/66387822 - Part 6
www.dpreview.com/forums/post/65906028 - Part 5
www.dpreview.com/forums/post/65600385 - Part 4
www.dpreview.com/forums/post/65291223 - Part 3
The Optical Bench Hub maintained by Bill Claff at Photons to Photos is the largest database of patents that can be matched to an actual production photographic lens.
I also maintain a subset of Nikon related patents list at Nikon Nikkor Lens Patent Database. My goal is to find the best match for a production lens, that may or may not be an exact match.
The lens patent data can be used to analyze the lens theoretical performance. For instance, using the open source ray-optics package maintained by Michael Hayford, following is a Jupyter Notebook that looks at the Canon 50mm RF f1.2 lens.
Patents also reveal who is behind a particular lens design.
Many modern Leica, Zeiss branded lenses are actually designed by Japanese firms!
Nikon collaborates with other companies too!
I intend to copy across the lenses that are not covered by Bill Claff, to start with. The ones already covered by Bill in his database, can be found at The Optical Bench Hub.
The Sigma 40mm f1.4 ART lens is one of the most elaborately designed lenses for a prime.
It is a Zeiss Otus class lens at a fraction of the price. Its design incorporates 3 fluorite class Super ED glass elements, and three ED glass elements. Although not branded APO it is very much an apo-chromatic design.
Patent JP2018134615A - 2018.
Using patent data:
More detailed analysis from patent data using Michael Hayford's ray-optics.
Nikkor Z 20mm f1.8S
This is an example where the patent is the best rather than exact match for the production lens.
The patent is WO2021117429A1.
Cosina Voigtlander SL Macro Apo Lanthar 125 mm f/2.5
This lens has legendary status amongst many photographers.
The related patent is JP2002090622A, designer Yoshihisa Yomogida, 2000.
Cosina Voigtlander Apo-Lanthar 180mm f4
Patent JP2003270529A, also by YOMOGIDA YOSHIHISA, 2003.
Cosina Voigtlander 50mm f2 Apo-Lanthar
Related patent JP-2021-043376.
From the patent
Cosina Voigtlander Nokton D35mm F1.2 (Z mount)
Related patent JP2022-128635A
It seems that there are some problems with this patent. The original data give a 104mm focal length instead of 100mm, which is not within the margin of error. Also I sent you a PM :)
