Focus Offset in NINA?

[Ratlet]

Hopefully our resident vintage glass expert @alacant will show up for this.

I'm in the process of building an autofocusser and due to the nature of ordering the parts I'm likely to be able to build one for each of my vintage Takumar lenses (135mm and 200mm).

From previous discussions I know that Takumars tend to focus blue and green differently to red.  This means that when you get the image in focus (with a bahtinov mask) you will get red halos and what you need to do is get it in focus then slightly defocus it.  You're basically making everything equally defocussed very very slightly so you get good stars without halos.

My question is whether it is possible to automate this in NINA or similar during an autofocus routine?  Some sort of offset you can program in (find focus and then defocus by x steps for example).

[TiffsAndAstro]

There's some decently reviewed £60 ones on Ali express

[Ratlet]

46 minutes ago, TiffsAndAstro said:

There's some decently reviewed £60 ones on Ali express

Yeah, the Gemini came out about 20 minutes after I started building my own 😂.

I'm kind of in it for the journey rather than the end result at this point.  I'm confident the unit will work as it's a myfocuspro2 unit I'm building, just need to figure out if it'll play ball with vintage glass.

[alacant]

2 hours ago, Ratlet said:

autofocusser

Are you sure you need one? But anyway...

Sorry, can't help with autofocus or autofocesers. I've never had the need to use one. Not sure where you are but here, we focus once at the beginning of the session and let it run. I think it's temperature dependent. We have little fluctuation, which may explain why. YMMV.

Either that, or they're a gimmick.

Cheers and good luck with the project.

 

[Ratlet]

On 09/08/2024 at 22:22, alacant said:

Are you sure you need one? But anyway...

Sorry, can't help with autofocus or autofocesers. I've never had the need to use one. Not sure where you are but here, we focus once at the beginning of the session and let it run. I think it's temperature dependent. We have little fluctuation, which may explain why. YMMV.

Either that, or they're a gimmick.

Cheers and good luck with the project.

 

Ah, was hoping you used them as you're very knowledgeable on working with vintage glass.

With any luck the project will go well.  , but we shall see.

[assouptro]

Nina has a good offset routine in the advanced sequencer 

you have to train your focuser to calculate the offsets taking into consideration the backlash the offsets can be done by pressing a button and letting it run 

mit takes time, but can be time well spent if you can afford to give up a couple of hours when clear 

patriot Astro on YouTube has some great instructions and advice including some advanced sequencer templates you can just plug into Nina and modify for your requirements!

Cheers 

Bryan 

[Ratlet]

That is exactly what I am looking for I think.  I think I just need to find calculated focus, and then determine the focus that gives me the best stars and use that as an offset.

Not completely sure how I'll get it to think that I've changed the filters but I'm sure that it will be possible in either hardware or software.

Thanks @assouptro