E-mount electronic protocol reverse engineering

Entropy512 wrote: Also, we know based on the Sigma MC-11 and Phigment LM-NEX that the lens can report distortion/vignetting profiles to the body so that the camera does not need to maintain a database of lens profiles for correction.

Are you sure about that? I thought the camera look-up table was the only source of correction data, which is why other manufacturers have to pick an existing lens ID before they can auto-focus.

Miranda F wrote: I thought the camera look-up table was the only source of correction data, which is why other manufacturers have to pick an existing lens ID before they can auto-focus.

This was/is true of A-mount. To my knowledge there has been no indication that it's true of E-mount.

sybersitizen wrote: Bob J wrote: My understanding is that the basic specification for e mount is available as a free licence... would that specification include the information you are trying to gather... As explained on that page, the specs are not offered to individuals. They are offered to companies that sign a non-disclosure agreement and meet other criteria.

Granted, but I just wanted to confirm if that specification would include the information being sought...

sybersitizen wrote: Bob J wrote: Granted, but I just wanted to confirm if that specification would include the information being sought... Only people who have been granted access can give a complete answer - but it must be yes in order for manufacturers to produce properly working lenses and adapters.

I would disagree here. Reverse engineering is the way this sort of thing has been done for many years. That announcement was back in 2011, and since then - we've seen no evidence of anyone that does not have an extensive cross-branding agreement with Sony (Zeiss and Tamron) having any sort of documentation.

Techart III is unbelievably buggy.

Metabones IV is the most mature adapter out there, and they explicitly state that they received no assistance from Sony. If there's any company that would be eligible for the specifications, it would be Metabones/Conurus by virtue of being the most well-regarded electronic adapter manufacturer out there.

Sigma's first E-mount autofocus attempt was notably flawed with a bunch of limitations. They didn't even try another E-mount product for another 3-4 years, and I have seen others claim their CEO has been quoted as saying the mount was difficult to work with.

All of the evidence that can be seen in the E-mount product landscape says that the term "basic" in that specifications announcement is much more limiting than people think it is (Perhaps mechanical specifications only?) or the licensing terms are really nasty with non-monetary costs that no one is willing to pay.

On another subject, as to lens vignetting/distortion profiles - for E-mount it's definitely coming from the lens.

For example, from Sigma's MC-11 product description- "MOUNT CONVERTER MC-11 incorporates the digital data necessary to provide fast and smooth AF for compatible lenses as well as OS features and functions of the camera that help control peripheral brightness and correct transverse chromatic aberration, distortion, and more.". Also, Phigment Tech's LM-NEX supported automatic vignetting correction - https://www.phigmenttech.ca/lmnex/index.php?page=config&sensormode=2&model=1.1

Entropy512 wrote: sybersitizen wrote: Bob J wrote: Granted, but I just wanted to confirm if that specification would include the information being sought... Only people who have been granted access can give a complete answer - but it must be yes in order for manufacturers to produce properly working lenses and adapters. I would disagree here. Reverse engineering is the way this sort of thing has been done for many years. That announcement was back in 2011, and since then - we've seen no evidence of anyone that does not have an extensive cross-branding agreement with Sony (Zeiss and Tamron) having any sort of documentation. Techart III is unbelievably buggy. Metabones IV is the most mature adapter out there, and they explicitly state that they received no assistance from Sony. If there's any company that would be eligible for the specifications, it would be Metabones/Conurus by virtue of being the most well-regarded electronic adapter manufacturer out there. Sigma's first E-mount autofocus attempt was notably flawed with a bunch of limitations. They didn't even try another E-mount product for another 3-4 years, and I have seen others claim their CEO has been quoted as saying the mount was difficult to work with. All of the evidence that can be seen in the E-mount product landscape says that the term "basic" in that specifications announcement is much more limiting than people think it is (Perhaps mechanical specifications only?) or the licensing terms are really nasty with non-monetary costs that no one is willing to pay. On another subject, as to lens vignetting/distortion profiles - for E-mount it's definitely coming from the lens. For example, from Sigma's MC-11 product description- "MOUNT CONVERTER MC-11 incorporates the digital data necessary to provide fast and smooth AF for compatible lenses as well as OS features and functions of the camera that help control peripheral brightness and correct transverse chromatic aberration, distortion, and more.". Also, Phigment Tech's LM-NEX supported automatic vignetting correction - https://www.phigmenttech.ca/lmnex/index.php?page=config&sensormode=2&model=1.1

Those adapters might be buggy, but that may be down to the Canon side - which may well need to be reverse engineered.

Bob J wrote: Those adapters might be buggy, but that may be down to the Canon side - which may well need to be reverse engineered.

While it does need to be reverse engineered, the protocols have been around for so long that the results of REing them are, at this point, something you can find with a Google search. https://pickandplace.wordpress.com/2011/10/05/canon-ef-s-protocol-and-electronic-follow-focus/ for example

A number of companies have made products to control EF-mount lenses that work extremely well - see Blackmagic Design's EF-mount cameras for example.

Plus you can see plenty of evidence of problems on the Sony side of things. For example Techart hardcoding the third focus position field (used to calculate subject distance) in message 0x30, and also always reporting the same focus position for both current and predicted motor position in 0x30.

Miranda F wrote: YOu may well be right in your assertion, but to my mind it is not proved by this quote.

I can understand you thinking that for Sigma's quote, but the Phigment LM-NEX vignetting profile feature/capability is unambiguous here.

sympa wrote: --- That happens before the EF mount comes into action.

Do you mean Canon EOS fullformat (EF) mount, which was launched 1987? Or
Sony E-mount, where the fullformat lenses (stamped FE) were launched 2013-Oct-16 ? :-)

Edited by Swede101 - 10 May 2016 at 19:45