Hello , I recently purchased a canon full frame rokinon 135 full setup with the EAF focuser. Can anyone get the ASIAIR to autofocus the lens using the AIR? There are instructions online to modify the lens to focus past infinity. I believe that it may need to be modified in that way to go past infinity in order to autofocus correctly. Is it able to autofocus using the air without modifying the lens? I plan to use this lens at f/2.8. I have used the EAF before and autofocus works flawlessly on my redcat, but the redcat will focus past infinity so I didn't experience any issues there. If anyone is using the canon, what backfocus have you found to be optimal? I have the canon lens and a 2600mc. it is my understanding that the backfocus is 44mm. just would like to see what others may be using if you have the same lens. Also, regarding a dew strap, where do you put it? The rings prevent me from putting it just behind the front lens. if I put it as far back as I can on the dew shield will it work? Any help you anyone can provide or tips imaging with this lens would be greatly appreciated.Regards,Itto Ogami
Questions using the Samyang 135 and EAF focuser
Itto Ogami:
Can anyone get the ASIAIR to autofocus the lens using the AIR?
Hi Itto - I've used the EAF with my Samyang 135mm and ASIAIR Pro (AAP) - the EAF sits on top with a belt driving the focus mechanism. I also shoot at around F2.8 usually.
My focus ring stops just to the right of the "L". Due to the orientation of my EAF I enabled "Reverse" in my AAP so any large movements would go left and not towards infinity.
I found a small step size (25) works fine. If you start "in focus" it'll go to a star size of about 5, then work back to focus and past it. Finally it'll do the fine movements to bring it back in. I find this setup works 95% of the time (if it doesn't it's usually sky conditions).
I'm not sure where an average Samyang 135mm lens focus ring stops out of the box or whether we should change this stop point to support autofocus. I'd be interested in others thoughts on this too.
Itto Ogami:
it is my understanding that the backfocus is 44mm
Agreed. I use a mono camera with 1mm thick filters, so I make my backfocus 44.3mm. This brings it under the "L" as mentioned above.
On my lens (and many others from what I see in images) the Red focuses quite differently to the Green & Blue - certainly at F2, F2.4 and F2.8. My Green, Blue and OIII all focus almost the same. My Red and Ha are similar but a lot different to G and B.
Itto Ogami:
Also, regarding a dew strap, where do you put it?
My fixings allow it to be at the back of the lens hood. I think far back of the lens hood / dew shield should be OK - just do a test.
Hope the above helps
Lee
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Thanks so much for your answers Lee!! Its appreciated 
Itto
I had initial focus issues with the EAF and Rokinon 135mm along with the ASI air. I was able to solve the problem by setting the ASI air to small step size 10-20 and then changed it to only move in one direction. This prevents the EAF from hit the focus stop point near infinity. I had already got rough focus with the manual focus before completing the auto routine. It was worked great sense. Here is my first light without flats with the 135 mmm rig and a mono ASI 294 mm: https://www.astrobin.com/52x6em/
CS - Brandon
I had initial focus issues with the EAF and Rokinon 135mm along with the ASI air. I was able to solve the problem by setting the ASI air to small step size 10-20 and then changed it to only move in one direction. This prevents the EAF from hit the focus stop point near infinity. I had already got rough focus with the manual focus before completing the auto routine. It was worked great sense. Here is my first light without flats with the 135 mmm rig and a mono ASI 294 mm: https://www.astrobin.com/52x6em/
CS - Brandon
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Brandon Tackett:
Here is my first light without flats with the 135 mmm rig and a mono ASI 294 mm:
Brandon, Awesome image! Thanks for the advice
This was taken at f/2?Thanks. Shot 2.8. I believe it was two stops down on the ring.
Here is my version of the heart and soul after adding flats. Vignetting almost completely gone and mild coma in 2 corners, but light years better focus and coma with the eaf set up. I only cropped out the edge stacking artificats. Definitely open to thoughts and critiques.
https://www.astrobin.com/52x6em/C/
https://www.astrobin.com/52x6em/C/
Hello Folks!
I just joined the group today...
I had this issue with focusing past infinity. It was very frustrating because I could not find a solution until I came upon this YouTube video from one of our Astrobin colleagues, Nico Carver. I performed this minor surgical procedure on my Samy and it worked perfectly.
https://www.youtube.com/watch?v=Yk2myVjAFlU
I just joined the group today...
I had this issue with focusing past infinity. It was very frustrating because I could not find a solution until I came upon this YouTube video from one of our Astrobin colleagues, Nico Carver. I performed this minor surgical procedure on my Samy and it worked perfectly.
https://www.youtube.com/watch?v=Yk2myVjAFlU
Helpful
Michael Feigenbaum:
Hello Folks!
I just joined the group today...
I had this issue with focusing past infinity. It was very frustrating because I could not find a solution until I came upon this YouTube video from one of our Astrobin colleagues, Nico Carver. I performed this minor surgical procedure on my Samy and it worked perfectly.
https://www.youtube.com/watch?v=Yk2myVjAFlU
Hi Michael!
I finally had a chance to try out the AEF with ASI Air and the Samyang last night.. could not get the AF to work.
This morning I think I have figured out why.. Problems you have all mentioned. The focuser was hitting the hard stop limit on the Lens.
There is a setting in the Focuser tab on the ASI Air app where you can disable the reverse setting. I disabled it. Now the initial movement of the focuser during the AF routine moves it away from the hard stop then slowly comes back. I will test it out tonight. Hopefully it works. Otherwise I will change the stop on the Lens as you mentioned you did. Thanks for sharing the link buddy!
Mike
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Elmiko:Michael Feigenbaum:
Hello Folks!
I just joined the group today...
I had this issue with focusing past infinity. It was very frustrating because I could not find a solution until I came upon this YouTube video from one of our Astrobin colleagues, Nico Carver. I performed this minor surgical procedure on my Samy and it worked perfectly.
https://www.youtube.com/watch?v=Yk2myVjAFlU
Hi Michael!
I finally had a chance to try out the AEF with ASI Air and the Samyang last night.. could not get the AF to work.
This morning I think I have figured out why.. Problems you have all mentioned. The focuser was hitting the hard stop limit on the Lens.
There is a setting in the Focuser tab on the ASI Air app where you can disable the reverse setting. I disabled it. Now the initial movement of the focuser during the AF routine moves it away from the hard stop then slowly comes back. I will test it out tonight. Hopefully it works. Otherwise I will change the stop on the Lens as you mentioned you did. Thanks for sharing the link buddy!
Mike
Nice one Mike. I have the reverse option selected due to the orientation of the EAF otherwise I hit the same issue. You still need a little bit past the crtical focus to make the curve but the big initial movements go away from the infinity stop. Hope you get it sorted.
Lee:Elmiko:Michael Feigenbaum:
Hello Folks!
I just joined the group today...
I had this issue with focusing past infinity. It was very frustrating because I could not find a solution until I came upon this YouTube video from one of our Astrobin colleagues, Nico Carver. I performed this minor surgical procedure on my Samy and it worked perfectly.
https://www.youtube.com/watch?v=Yk2myVjAFlU
Hi Michael!
I finally had a chance to try out the AEF with ASI Air and the Samyang last night.. could not get the AF to work.
This morning I think I have figured out why.. Problems you have all mentioned. The focuser was hitting the hard stop limit on the Lens.
There is a setting in the Focuser tab on the ASI Air app where you can disable the reverse setting. I disabled it. Now the initial movement of the focuser during the AF routine moves it away from the hard stop then slowly comes back. I will test it out tonight. Hopefully it works. Otherwise I will change the stop on the Lens as you mentioned you did. Thanks for sharing the link buddy!
Mike
Nice one Mike. I have the reverse option selected due to the orientation of the EAF otherwise I hit the same issue. You still need a little bit past the crtical focus to make the curve but the big initial movements go away from the infinity stop. Hope you get it sorted.
I recently purchased the 3-D printed Astrodymium mount. It's a nicely crafted piece of gear that holds the Samyang 135 Lens, guide scope, EAF and the ASI Air.
I was having problems with the AF routine the first time out. The focus position with my Lens is fairly close to the hard stop...or limit in one direction.
When the AF routine started it would go in the reverse direction and hit the hard stop and fail to auto focus. I ended up disabling the reverse mode in the ASI Air app. So now when the AF starts it goes forward away from the limit ( hard stop) and is able to move in both directions to create the v curve necessary for a successful AF. I know that some folks have done surgery on the Samyang Lens by moving the hard stop position by removing the small screws under the focus ring. I didn't have to in my case. Lucky for me... I would have lost the tiny screws. Thanks for your suggestions Michael!!!
CS Mike
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