Polar align with Sharpcap vs NINA app

andrea tasselli:
SharpCap is good but NINA 3-points (or manual drift-rate approach) is better and this is all down to resolution. With the former you are constrained to a large FOV and small FL and therefore larger error due to large image scale, the other two are using native resolution and image scale and thus, potentially, a much better resolution. The same applies using polar scopes and cameras such as iPolar (in fact they are probably worse than SharpCap).

Thank you Andrea - and yes, I agree - iPolar, which I also have but not in use, is much worse than SharpCap. Interesting thought.... I shall definitely consider it!

CS
Georg

I personally like the SharpCap PA but it requires disconnecting my camera in NINA and delays cooling.  I'd rather cool the camera while doing PA and other things in prep for the night.  I have found the three point PA in NINA to be just fine.  Keep in mind when guiding having perfect PA is not ideal.  Just need good enough

I personally like the SharpCap PA but it requires disconnecting my camera in NINA and delays cooling.  I'd rather cool the camera while doing PA and other things in prep for the night.  I have found the three point PA in NINA to be just fine.  Keep in mind when guiding having perfect PA is not ideal.  Just need good enough

Why is a perfect PA not ideal? Deviations from a perfect PA contribute in my opinion to an increase of FWHM due to increased guiding activities because of DEC errors?

Georg N. Nyman:
Why is a perfect PA not ideal? Deviations from a perfect PA contribute in my opinion to an increase of FWHM due to increased guiding activities because of DEC errors?

If your mount is perfect mechanically then it's fine.  And maybe the strain wave mounts are better here, but my understanding is having PA out by even 5 arc min is OK because it will help keep guiding moving in one direction in both RA and Dec.  I believe this talk from 2019 AIC is where I saw this.  https://www.advancedimagingconference.com/articles/2019_Galasso 

I still try to get pretty close, under 1 arc min, but I don't sweat being exceptionally close.  For me, the results are acceptable.  Running a 0.63x reduced C8 on an EQ6-R Pro with an OAG.

I believe this talk from 2019 AIC is where I saw this.  https://www.advancedimagingconference.com/articles/2019_Galasso

thanks for that one. Really interesting point that I've never really thought of

the idea of leaving some level of misalignment, sort of feels like blasphemy. But, hard to argue with Andy.

Haakon Rasmussen:
I use SharpCap for PA . After replacing my finding scope with an OAG , i started using my Omegon 571 camera and 8" newton.  Resolution should then be sufficient high enough for more accurate PA.

CS Haakon

Assuming the FOV is large enough to ensure good matches when rotating 180 degrees I would still be weary of possible mirror shifts (which do happen in newtons) that make accurate measurements prone to fail.