dsb-vs-ml in 135

There might not be any diagrams online that are 'official' for the DSB line to be able to confirm the optical differences like there are for the ML's, so this is only a somewhat educated guess. It might be safe to assume that the company's intentions and targeting would cover a whole model line, and not just a single lens model, so I'd assume what was set out for the 135mm DSB would have been applied to the entire DSB family, and the same would seem likely for the other lines and their individual models too.

It's very possible that the optical diagram between lens families could have been identical - or near enough - but it wouldn't mean the results would have been the same between every family. Optical designs are only part of the final equation, so if you add on the use of coatings (single or multiples, of XYZ types), better shaping/grinding/polishing of the elements, precision binding and alignment of cemented groups, precision machining of the metal components to get tighter optical tolerances, plus the better and more costly glass formulas... there could be a huge difference in the final results.

Sizes might not really be a good indicator of anything, unfortunately. The Contax C/Y 85mm f2.8 sitting next to a Contax G 90mm f2.8 - where both have 5 elements in 4 groups - is one example where dimensions alone don't tell enough about the insides to judge by.

This is not directly related to any maker's lens models, but explains glass types used and the properties they have that can affect how well lenses work, and how good the resulting IQ can be. The exact same optical diagram might go from mush to magic with the right selections, and every element could potentially be completely different from each other in the final product.

A rather technical and geeky look at glass types, and the refractive indexes and chemical makeup offered in different and ECO/modern optical glass types. Click the links under "Introduction to Glass Properties" for even greater detail... www.oharacorp.com/catalog.html

One other way to keep costs down is in using molded glass as the lens 'starter' and then grinding/polishing from there, as opposed to using flat glass blanks and doing all the work to shape and polish them into the final elements needed. It's more time intensive, so it raises the cost with a better end result for IQ, than offered with the lower cost, molded glass shortcut method. I suspect the YUS line may have used molded glass, versus flat blanks for the ML's, and maybe the DSB line had a mix of both types - but that's purely speculation.

Another page, but much less geeky overall - with links to molded vs flat info... www.swiftglass.com/blog/what-is-optical-glass/