N.I.N.A. + MGEN-3 Autoguider Focal Length Setting?

Acquisition Guiding Deep Sky Help Needed
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Christian Koll avatar
Christian Koll avatar
Hello,

I just stumbled accross this - don't know if I have my focal lenght put in correctly in NINA's Guider Setup settings (see screenshot enclosed - circled with red ellipse). Don't bother on the German language setting, the word next to the red ellipse just means "focal length".

Am I supposed to enter my main telescope's focal length or the focal length of my guider scope?

My main telescope is an Esprit 100 with 550mm focal length.
My guider scope is a Sky-Watcher 50mm guider scope with 176mm (supposed to be 180mm, but actually 176mm) focal length.

Within MGEN's internal menu the guider scope focal length is set correctly.
Is this setting in NINA suppost to calculate my guding RMS for the main telescope?

The RMS values in arcsec should be identical for guider scope and main telescope, shouldn't they?
So my guiding RMS should be around 0.3" per axis, according what the MGEN-3 displays, right?

So I guess I'll have to enter 176mm in NINA for this to display correctly, right?

Thanks for your help!
Chris

PS: Unfortuantely the NINA or MGEN manuals don't tell you anything about these settings.
I know there is a Discord group for NINA support, but I could not manage entering into Discord...

Marcus Jungwirth avatar
Marcus Jungwirth avatar
Hallo Christian,

Ich habe mit dem Mgen3 die Polarausrichtung gemacht. Da errechnet er sich im ersten Schritt mit platesolve die korrekte Brennweite. Die ist dann im Mgen sowieso gespeichert. Sicherheitshalber würd ich das bei Nina auch eintragen, ist glaube ich aber irrelevant da das Guiding ohnehin der mgen macht. Hoffe es war hilfreich und funktioniert. 

LG Marcus
Christian Koll avatar
Christian Koll avatar
Marcus,

thanks very much - guiding works like a charm - so no issue, other than the not matching RMS values in arcsec displayed by MGEN-3 and NINA.

Maybe this is a too specific question and better put into the NINA Discord cahnnel.

I believe this is a bug in NINA:
RMS-values in arcsec should stay the same, no matter what the focal lengt is (that's the point of using arcsec in the first place).
The only difference should be RMS in pixels, depending on focal length (RMS arcsec divided by pixel scale = RMS in pixels).
But NINA calculates RMS in arcsec and pixels depending on focal length.

CS
Chris
Christian Koll avatar
Christian Koll avatar
Marcus Jungwirth:
Ich habe mit dem Mgen3 die Polarausrichtung gemacht. Da errechnet er sich im ersten Schritt mit platesolve die korrekte Brennweite. Die ist dann im Mgen sowieso gespeichert.


Ja, Polausrichtung/Brennweitenmessung habe ich gemacht - es läuft auch alles einwandfrei und ich bin mit dem Guiding sehr zufrieden.

Es geht nur um die Anzeige in NINA, welche nicht mit der im MGEN übereinstimmt.
Bei einer RMS-Anzeige in Bogensekunden spielt die Brennweite keine Rolle, NINA rechnet jedoch auch die Werte in Bogensekunden um.
Ich denke, es handelt sich hier um einen Software-bug in NINA.

LG
Christian
Well Written Concise
Marcus Jungwirth avatar
Marcus Jungwirth avatar
Hallo @Christian Koll,
ich achte bei der nächsten Session mal drauf und berichte wie's bei mir ausschaut. 
LG Marcus
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