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Samyang/Rokinon 135mm ZWO EAF - NINA V Curve

Rokinon 135mm f/2.0 ED UMC Sony A7III ZWO EAF Auto-Focusing Troubleshooting
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LookSpaceThings avatar
LookSpaceThings avatar
Hello!

I have built a rig with the Samyang 135mm, ZWO EAF, Astrodymium Ring System and a mirrorless camera (Sony A7III astromod).

It was easy to put them all together and the EAF can control very well the focus.

The issue is that the focus point in very near the hardstop so when I run NINA autofocus routine it cannot make a proper V curve.

I have followed  @Nico Carver tutorial on how to adjust the infinity focus by removing the hard stop but I do not think it is going to work for this particular issue  (I have not tested yet, clouds )

https://www.youtube.com/watch?v=Yk2myVjAFlU&list=PLEn7nyeL4szTZDziU3-iJTZNM_-bqRuBL&index=11&t=287s

Does anyone knows a solution for this issue?
Walter Leonhard Schramböck avatar
Walter Leonhard Schramböck avatar
I never had this issue, but I am using an Asiair for my Samyang-rig, not NINA, because my mobile setup has to be lightweight and fast to prepare.
Michael Ring avatar
Michael Ring avatar
In the Autofocus Settings of Nina you can see the Backfocus in/out settings, only use one of the two fields and make sure that the movement created by this setting is away from infinity and not towards infinity. That solves the issue. Also the Hardware Mod should have solved your issue.

What happens is that to compensate for backlash the Focusser is moved in the opposite direction of adjustment first, when this movement is in direction of infinity you will usually always hit the hard stop. When you set this movement away from infinity then this will never happen.

Michael
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