Software Polar Alignment Methods - PHD and Sharpcap

[tim.anderson]

PHD offers two different polar alignment methods (drift and static) and Sharpcap provides one (static).

I have repeatedly tested each method on the same night and get markedly different results (sometimes several arc-minute differences between the three methods). Before each test, I return the altitude and azimuth settings to a marked position on the mount.

Can anyone comment on which method is most accurate and reliable?

Thanks

Tim

[doppler]

The marked position on your mount is still a variable in the equation. I have a marked spot on my my mount but still have to tweak alignment each time I set up (a tiny variation here makes a big difference). The end result is what counts how you get there is only an issue as to the time and ease to achieve it.

[Imme]

I was using PHD drift and was getting very frustrated with the time it took.
I changed to Sharpcap and am blown away by the quick and accurate results I get. I imaged last night and guided with less than 1" error over the 5 hour session......cant argue with that

[LewisM]

I am a bit mixed bag.

PHD2 Drift align and Static align have been VERY frustrating for me. The static align gave me wild results - almost 20° out from prior known good positioning with a compass and an old-style drift align (that gave superb tracking).

Sharpcap has been mixed, but in a not positional issue. The issue I have is sometimes, even though the signal is strong, good image etc (using a Lodestar - with the updated settings etc it works superbly in Sharpcap) that a pllate solve can take up to 5 minutes even though I can see the trapezium of octans in the image. It seems to lag for some reason. Yet other times, it will do the initial solve instantaneously. Weird. Once u[pp and going from my set position (see my "observatory" post), and if I have NOT touched mount settings, it takes 5 minutes to get to excellent, mere seconds alignment.

So, for me anyway, PHD2 polar alignment methods fail miserably, where Sharpcap has it's peculiarities, but is very reliable for me positioning wise. I also bought and tried Polemaster - hated it - and sold it (I got better results aligning with a compass)

[glend]

In the field, like at Coolah last week, i use Sharpcap and work off my imaging camera (ASI1600). Very quick but i don't need it to be too precise as the CGX alignment routine is excellent. At home in the observatory the CGX sits in a previously marked position, with Az positions marked on the mount base as well. I just align the base marks, check the Alt with my inclinometer, and i am ready to go. I has targets sitting right on the centre of the camera cross hairs at Coolah, and every goto was the same.

[kens]

There are three methods in PHD2 - original Drift Align (near dec 0), Polar Drift Align and Static. Original drift align is the most accurate but takes time. Static is faster and almost as accurate, certainly "accurate enough" but can be finicky. Polar drift is the least accurate but incredibly simple. I recommend staring out with Polar drift, followed by calibration then fine tune with either static or original drift. I'm putting together a video tutorial on the two new methods

[kens]

I can help you out with SPA if you want - I wrote it. it is critical to have the right orientation of the star map, correct pixel scale and delete all sync points. Manual mode is more reliable than automated mode but takes longer.