Thanks Mark. lenstip published a long interview with the optical engineer that designed the outstanding Sigma 35mm f/1.4 DG HSM (price & specs) and Sigma 18-35mm f/1.8 DC HSM (price & specs) lenses. The interview comes with lots of b&w images that appear to represent Sigma’s laboratories. Some excerpts from the interview:
Q:What is more important today: intuition and experience or an access to new software and fast computers[…]
A: We think that both are important. Although it is necessary to use machines perfectly, we cannot come up with creative ideas if we rely too much on technologies. Sometimes it is necessary to advance it with own judgment while considering about the purpose and results at all times.
Q:At what point do you start thinking about the usage of antireflection coatings? Does an optics specialist think of them already at the beginning of their work or do they just optimize the final product according to the elements used in the construction or their refraction coefficient?[…]
A: We start thinking about the usage of antireflection coatings from the middle stage of the design.
Q:In the case of such a unique construction as the Sigma 18-35 mm f/1.8 which parameter was set as the first? The focal range? The aperture? Or perhaps the image quality was the main priority and you adjusted the rest of parameters accordingly?
A: The project had started with a lens incorporating a maximum aperture of F1.8 and 2x zoom-ratio lens with a focal length equivalent to 50mm in a 35mm format. After some speculation, we decided to produce the 18-35mm f/1.8 lens because it seemed to be able to achieve the highest performance with this spec.