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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 11 Dec 2010 (Saturday) 17:22
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Reverse-engineering Canon EF lens protocol

 
Chweps
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Mar 30, 2011 06:29 |  #61

Hey guys,

I'm actually trying to make exactly the same thing ! Good job for the reverse engineering.

I'm going to try reverse engineering with :
Canon EOS 1000D + lenses EF 85mm f/1.8 USM + extension lenses Kenko 12mm (it is modified to connect my electronic board of devlopement). I'm going to start as soon as I receive all this products.

I've found some interesting informations, you can see there are 4 kinds of USM motors here (p.21) ->http://software.canon-europe.com …F_Lens_Work_Boo​k_9_EN.pdf (external link)

So there are 2 MIcro-motors USM and 2 rings motors USM and and I think the datas to send them is different for each motors...

You can also see on page 8, informations about which datas are transmited.

Can you tell me more about :
- the micro controllers you use
- how do you "listen" the communication between lense and camera? Do you use logic analyzer?
- what are the power supply voltage for motor and electrmagnet ? I have seen there is only one pin for voltage, il supplies both ? It seems strange.

I don't understand why do you need a teleconverter? 8 pins are sufficient to control aperture and focus of some of Canon lenses ; a teleconverter adds 3 more pins to listen so this more complicated.

This will be very cool if we could work together !




  
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ken_vs_ryu
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Mar 30, 2011 07:15 as a reply to  @ Chweps's post |  #62

here's a Sony NEX controlling an EOS lens' aperture
http://sonyalphanex.bl​ogspot.com …ontrol-for-canon-eos.html (external link)


http://google-black.blogspot.com (external link)

  
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AntonLargiader
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Mar 30, 2011 07:27 |  #63

I remembered a note from this link:
http://www.usa.canon.c​om …ArticleAct&arti​cleID=3602 (external link)

"The IS mechanism is automatically disabled when tripod use is detected and the shutter speed is longer than 1 second."

So, there is some communication from the camera to the lens regarding the shutter speed. Either the lens knows the shutter speed, or the lens know that it's something over one second.


T2i . 18-55 IS . 70-300 IS USM . 70-200 2.8L IS . 28mm 1.8 . 100 Macro . 430EX II . TT1/TT5 . Bogen/Manfrotto 3021 w/3265 ball-mount

  
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RDKirk
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Mar 30, 2011 07:40 |  #64

AntonLargiader wrote in post #12123181 (external link)
I remembered a note from this link:
http://www.usa.canon.c​om …ArticleAct&arti​cleID=3602 (external link)

"The IS mechanism is automatically disabled when tripod use is detected and the shutter speed is longer than 1 second."

So, there is some communication from the camera to the lens regarding the shutter speed. Either the lens knows the shutter speed, or the lens know that it's something over one second.

The lens may not "know" anything. It might work like this: The camera is supplyling power to the IS mechanism, so it can meter the level of activity (or the lens may directly report its level of activity). The camera notes that IS activity is below a certain level, checks the shutter speed itself, and send a command to the lens, "Stop IS."




  
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AntonLargiader
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Mar 30, 2011 07:46 |  #65

It's hard to know what happens when there's 2-way communication. My impression reading the Canon bit was that it is a feature of the new lenses, so unless that subroutine has been lying dormant in all of the older EOS bodies, the implementation would seem to lie in the lens firmware.


T2i . 18-55 IS . 70-300 IS USM . 70-200 2.8L IS . 28mm 1.8 . 100 Macro . 430EX II . TT1/TT5 . Bogen/Manfrotto 3021 w/3265 ball-mount

  
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RDKirk
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Mar 30, 2011 08:22 |  #66

AntonLargiader wrote in post #12123251 (external link)
It's hard to know what happens when there's 2-way communication. My impression reading the Canon bit was that it is a feature of the new lenses, so unless that subroutine has been lying dormant in all of the older EOS bodies, the implementation would seem to lie in the lens firmware.

If the older bodies do shut off IS on the tripod. That consideration is just as problematical even if the lens is doing the calculation, because no earlier lens ever needed to know the shutter speed...so it's likely earlier cameras don't communicate that information to the lens.




  
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charithjperera
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Mar 30, 2011 08:42 as a reply to  @ RDKirk's post |  #67

If it doesn't get shutter speed data it may just keep the IS going regardless, probably backwards compatibility build into the lenses.
Also about IS - the lens is probably able to detect tripods because the camera usually wouldn't have any sensors to detect it (except for the 7D's accelerometer).
If the Gyro's on the lens detect below a minimum threshold or detect feedback it may cut off the IS automatically? then that feature would work on any body.




  
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RDKirk
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Mar 30, 2011 09:13 as a reply to  @ charithjperera's post |  #68

This just shows why a good job of reverse-engineering the protocol will be very interesting.




  
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Matteo ­ Ricchetti
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Apr 27, 2011 16:50 as a reply to  @ RDKirk's post |  #69

Hello, this is my first attempt to make a remote controller for EF lenses based on pic.

http://www.vimeo.com/2​2715163 (external link)




  
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sardines
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Apr 27, 2011 19:24 |  #70

macroimage wrote in post #11435983 (external link)
This device already exists from Novoflex:
http://www.bhphotovide​o.com …EG/Novoflex_EOS​RETRO.html (external link)

It has a reverse mount for the camera and a cable to the collar to put on the "front" of your reversed lens that passes the camera contact connections to the reversed lens. This gives full in camera control as the camera thinks the lens is on normally. The Novoflex device is expensive so maybe there is a market for a simple battery operated aperture control that clips onto the end of the lens.



You can just buy a macro lens at that price.... stupidly silly price.


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nnikba
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Jun 04, 2011 22:40 as a reply to  @ sardines's post |  #71

This is the most elaborated project i found so far on line,
Great job here,

I was start looking how to control and display the aperture of EF lens in order to adapt to other camera as Panasonic AF101 or the new Sony 100.

Right now, my prototype only copy the order from an old 350D and i disconnect it as soon as the aperture is done to keep it this way.

There is a lot of room on the Panasonic and Sony ring adapter, so it make easy to work in.

Please let me know if you are interested on sharing iris control command with us, i also have asm programmer background, and a lot of idea on the use of this!

Nnikba


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nnikba
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Jun 04, 2011 22:43 as a reply to  @ nnikba's post |  #72

And 2 other picture of this working,

The next step is to have the motor 5 v disconnected in order to keep connection alive,
And put the 350D in a box with external power supply.

Nnikba


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toffiloff
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Jun 05, 2011 03:04 |  #73

As an embedded systems engineer, I love this work :D Keep it up! Been thinking of trying this myself, if I had some free time lying around


1D3 / 5D2-BG / 350D * 16-35 II f/2.8L * 24-70 f/2.8L * 70-200 f/2.8L * 135 f/2.0L * Σ85 f/1.4 * Σ50 f/1.4 * Σ15 f/2.8 FE * 580-II EX -- flickr (external link) -- twitter (external link)

  
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Chweps
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Jun 16, 2011 09:46 |  #74

Hey I can control aperture I know close it step by step but I can't open it step by step. I can only open it completely... Can you tell me what bytes did you send to open it step by step?
I'm going to control focus now.
I use an 50 mm EF f/1.8 II USM with eos 1000D.
Thanks !




  
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domrich
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Jan 10, 2012 16:10 |  #75

Hi I would like to remote control my EF-S 18-55 canon lens which is piggy back mounted on my telescope as a "wide field" camera with a meade DSI 3 camera. I would like to control mainly the focus. All information on the protocol you got is welcome. Right now I have information on the protocol (SPI) and any information on commands are welcome.
Thanks
Dominique




  
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Reverse-engineering Canon EF lens protocol
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