Canon Lens Adapter with access to focusing control

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Canon Lens Adapter with access to focusing control

Postby jmtanous » Sat Jan 06, 2018 4:58 pm

Hi Sam,

I like a lot the short backfocus of your cameras, it makes OAG a reality even with 56mm backfocus reducers.

I am looking to your Canon lens adapter solution and is amazing that you can squeeze a filter wheel between the lens and camera, this is fantastic specially for the new CMOS cameras with tiny pixels and smaller sensors.

The only missing bit of this solution is autofocusing, if you want to autofocus you need to add some pulleys and a stepper to the lens. However most Canon lenses already have the ability to autofocus, all the hardware required is already embedded in the lens.

I did some research and is is possible to control the lens parameters (focuser and aperture) externally with some auxiliary hardware (arduino). There is an ASCOM emulator to expose the Canon focuser mechanism as an ASCOM focuser. In other words all the bits are there to use the Canon built in focuser with a non-Canon camera.

It would be fantastic to include in your FW (or adapter) a board to control the lens or at least to expose the lens pins externally for easy addition of a logic board.

Some references:

http://www.indilib.org/media/kunena/att ... m_efEN.pdf

https://es.aliexpress.com/item/SLR-digi ... 4.5.mFFSCm

https://www.cloudynights.com/topic/5382 ... used-this/

Cheers,

Jose
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Re: Canon Lens Adapter with access to focusing control

Postby Sam » Thu Jan 11, 2018 8:42 am

this is not easy to do
and auto focus usually doesnot work well at night
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Re: Canon Lens Adapter with access to focusing control

Postby jmtanous » Thu Jan 18, 2018 8:50 pm

Sam wrote:this is not easy to do
and auto focus usually doesnot work well at night


Hi Sam,

The whole idea is to expose the internal lens focusing mechanism as an ASCOM focuser so we can use focusmax or any other astrophotography focusing software.

Cheers,

Jose
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Re: Canon Lens Adapter with access to focusing control

Postby Astrogate » Fri Jan 19, 2018 4:33 pm

Hi Jose

I agree with Sam if we're talking about auto-focusing a camera lens and a ZWO camera when imaging deep sky objects. Perhaps one can find a bright enough star like Vega and use FocusMax in order to complete a focusing V-curve but it is always best to manual focus. Now for autofocusing on brighter objects like the moon, planets or solar that would work great. Very good idea btw! I would say that it is always best to manual focus when it comes down to deep sky objects (stars) and use a Bahtinov mask.

Chris A
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Re: Canon Lens Adapter with access to focusing control

Postby jmtanous » Sat Jan 20, 2018 9:05 am

Astrogate wrote:Hi Jose

I agree with Sam if we're talking about auto-focusing a camera lens and a ZWO camera when imaging deep sky objects. Perhaps one can find a bright enough star like Vega and use FocusMax in order to complete a focusing V-curve but it is always best to manual focus. Now for autofocusing on brighter objects like the moon, planets or solar that would work great. Very good idea btw! I would say that it is always best to manual focus when it comes down to deep sky objects (stars) and use a Bahtinov mask.

Chris A


Hi Chris,

I respectfully disagree that that is better so use a Bahtinov mask than a good software based focusing solution. In my experience Bahtinov mask will get you close to focus, good enough for F/6 and slower but not enough for fast optics.

FocuMax will work just fine with a lens however you need to motorize it with an external stepper and pulleys. It would be great (and cheaper) to use the already built-in motor inside the lens to automate focusing or to manual focus without touching the equipment.

Cheers,

Jose
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Re: Canon Lens Adapter with access to focusing control

Postby Astrogate » Sat Jan 20, 2018 6:15 pm

Hi Jose,

I have focused using my Batinov mask and my camera lenses (Canon 100 mm f/2.8 prime & 70 to 200 mm f/4) quite well but I will admit that it is not easy. I am going to make some follow focus devices for both lenses. I would admit that it would be nice to have a motorized version like the one from Robofocusser that I once owned.

Chris
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