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Canon Expert advice needed

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#1 slavicek

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Posted 25 November 2019 - 10:54 PM

I've just got myself Canon 200 mm f/1.8 lens for use with NV and for "ordinary" observing as well. It looks like the "ultimate" fast and portable lens. yay.gif

 

However, what I did not realize is that this lens has manual focus "by wire" which means it will not manually focus unless it is connected to Canon EOS camera. undecided.gif

 

So the question is: is there a way of "hot wiring" the lens so that I could use the lens manual focus without EOS camera? Any help is greatly appreciated!



#2 dalbaugh

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Posted 25 November 2019 - 11:33 PM

not that i am aware of  that is one of the few that are"wired"

the discontinued EF 200mmm f/1.8 L, the EF 85mm f/1.2 L II, the EF 1200mm f/5.6 L, and the EF 200mm f/2 L IS as well as all the STM lens need power from the camera to focus manual or auto.

 

sorry

 

That lens is very desirable and you should be able to move it quickly.  The old non ef L lens are excellent choices for astro and can be pick up relatively inexpensively.



#3 Todd N

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Posted 26 November 2019 - 02:11 AM

I've just got myself Canon 200 mm f/1.8 lens for use with NV and for "ordinary" observing as well. It looks like the "ultimate" fast and portable lens. yay.gif

 

However, what I did not realize is that this lens has manual focus "by wire" which means it will not manually focus unless it is connected to Canon EOS camera. undecided.gif

 

So the question is: is there a way of "hot wiring" the lens so that I could use the lens manual focus without EOS camera? Any help is greatly appreciated!

 

Just buy a cheap used Canon EOS body and battery/charger to set the f-ratio. I imagine you could get one, even modded for $200 or less so, look in the Classifieds.

 

https://www.bhphotov...on&N=4294182649



#4 cmooney91

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Posted 26 November 2019 - 07:28 AM

Hi Slav,

 

This is Corey from ATMoB.

 

It looks like it is possible to control the lens with an Arduino.

 

Here are a couple examples.

 

https://pickandplace...c-follow-focus/

 

http://web.media.mit...t/move_lens.pdf

 

The first one taps into the lens control lines using a macro extension ring, which is non destructive but eats up 10mm of back focus.

 

The second one cuts open the lens, which is not so nice. 

 

Here are more resources

http://www.indilib.o.../ascom_efEN.pdf

 

http://howiem.com/wo...f-lens-hacking/


Edited by cmooney91, 26 November 2019 - 07:33 AM.

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#5 slavicek

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Posted 26 November 2019 - 02:20 PM

Hi Corey,

thank you for your help. bow.gif I hope you will be able to look thru the lens soon!

 

Last night I've soldered a Canon battery to the power pins on the lens, hoping this would do the trick for the manual focus. It did not work so there is more to it. I will read the articles you suggested before I proceed further...

 

Then, If everything fails, I will do what Todd N suggested, with a twist. I will buy cheap Canon camera, I will solder "extension" cable to the pins on the lens and to the pins on the camera body. This way the camera will not be in a way and I will be able to couple the lens with anything I want.

 

And even if that does not work then I will have to install some kind of mechanical telescope focuser on the back of the lens.

This lens just looks so nice and I am so excited about it that I will do anything to make it work! Just consider the numbers: max FOV=12 deg (think Ethos), with NV it's "only" 5deg, aperture diameter is 110mm!

Here are some pics:

 

canon1-8-nv.JPG

 

canon1-8-11.JPG

 

First pic is the lens with NV, second pic is the lens with 11mm Nagler.

It is not an accident why I've coupled it with 11 mm Nagler. The whole thing looks like Saturn 5! lol.gif

 



#6 ccs_hello

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Posted 26 November 2019 - 10:53 PM

EF lens is using Canon's proprietary (two-way) protocol communicating with the Canon body to do e-control.

(Essentially "fly by wire")

It is a form of extreme hack, not for casual DIYer.

 

BTW, this thread is better fit in ATM subforum, not truly EAA.



#7 Jeff Morgan

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Posted 26 November 2019 - 11:03 PM

Cool lens! Sorry I can't help, I am using the older manual (FD) lenses.

 

Can't wait to hear how it does with NV.


Edited by Jeff Morgan, 26 November 2019 - 11:04 PM.



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