How is the 35mm F1.4 GM so good?

Started 9 months ago | Discussions thread
joger Veteran Member • Posts: 7,070
surface coating might be one of the tricks

panther fan wrote:

What jump in technology allowed them to pull this off? All manufacturers have computer design and short flange distance. Sigma is no longer the underdog, they make a ton of premium lenses both for their own brand and other brands. Why is there no marketing around some new lens technology?

I've compiled a comparison based upon the data as an indication of the quality of the GM 35.

I am a materials science engineer and not specialized in optics - nevertheless it's all about physics.

Let me elaborate a bit about my take on Sony's approach, how I perceive it and what I think Sony does in a different way:

  1. The pedigree of Sony is miniaturization and ultra precise mechanics - IMHO that's the foundation of their projectors, walkmen, portable CD players and lately optics - Sony has a long history of enhancing serial manufacturing to a level where tolerances are almost eliminated and thus a high quality level is reached at a reasonable price level - they concentrate on making processes repeatable and automated to a high degree with lots of quality control in the creation of these processes - after all they are japanese and the call it Kaizen
  2. Computational brut force - when Sony released their GM 85 they indicated a bit of that by elaborating on the selection process of the lens grouping - they not only optimized the sharp areas but also the unsharp areas by selecting the designs that were sharp enough and had a beautiful sharpness fall off before and after the object in focus - that's a completely different approach to many others especially Zeiss and leica - they concentrate on sharp images - the Loxia 35 is a good example how to get it sharp but unpleasant wide open in the OOF areas. Sony is putting a lot of pre development and theoretical selection in the optical design - always with manufacturing capabilities in mind
  3. Surface treatment is at a new level - Sony is producing extremely flat surfaces that are almost a magnitude less rough than competition - they do that with a special manufacturing process they unfortunately don't disclose - no wonder
  4. Surface coating is also brought to a complete new level eliminating stray light and thus there is a low likelihood that light rays get a halo around the bright elements and thus more micro contrasts - my guess is that this new Nano AR Coating II is the foundation for that
  5. A further point of optimization are their XA lens elements ( extreme aspheric lenses with different shapes inside and outside ) - these are processed in a single glas pressing method ( I am a material scientist and when I was studying this was the holy grail for optical glas manufacturing ). Sony seem to have brought this process to a complete new level in tolerances in combination with size of these lenses - they are the first to have huge front elements manufactured in this process - thus the light is optimized till the corners already wirth the large front XA lens element. Such processes need special machinery and moulds and stamps and a very precise temperature guidance down to a 1/10th of a degree at high temperatures and of course specialized glas with precise constant mixture - ultra high end process that only a few companies are capable of and can maintain over time
  6. Clever design by grouping e.g. in the GM 35 six lens elements ( in case I counted it the right way ) in the focus group and thus this can be fully automated in assembly. My guess is that there are very few people manually involved in the manufacturing and final assembly process - this eliminates further tolerances and streamlines the design and thus also the longevity of the optical performance.
  7. Sheer brut force in investment - where other companies have to turn every penny twice Sony seems to set a goal and then they execute with all in. Sony has claimed in 2010 or so that they would like to become number one in the camera industry within the coming years - they've missed that target a bit but they are doing really well and their camera business is creating profits
  8. Last but not least clever engineers that do out of the box thinking plus clever marketing that is setting the right goals - e.g. with the GM 35 they obviously decided not to opt for f/1.2 but for slightly slower f/1.4 aperture to minimize size, weight and thus cost and maximize convenience - Sony has a clear target how to execute and that pays off plus the steep learning curve they've left behind and now we see for the past two or three years the enormous achievements of their progress in refinement

SONY's strict rules when deciding what to design

All in all I think the pedigree in miniaturization plus clever goal setting and the deep knowledge about the total system including the roadmap for their sensors brought them to a new level.

I doubt that there are many companies on this planet that can keep up with Sony - the only ones in electronics I'd rank similarly are Apple and Samsung to a certain degree in different fields of course.

Apple builds the best mobile devices and Sony builds the best mobile cameras - it's the sheer dedication and willingness to excel und to invest heavily in machinery and of course understanding the total scope of a design. The XD linear motors are the icing on the cream enabling ultra precise and ultra fast lens focussing. That's by the way also the reason why I dislike adapted SLR lenses on a MILC - these lenses have not been designed for precise focussing to the level that's needed with MILCs.

Last point - short flange distance - it gives much more freedom of design to the lens designers to be in a position to place the very last lens element as close as possible to the sensor - in case it is needed. This trums the SLR design by a good deal and enables designs that would never be possible on a SLR.

There might be other things that come into play and I think I've covered most of the important topics - yet - there may be also the kiss from the ferry to the engineers

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