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INDI Library v1.9.8 Released (29 Sep 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

What good does an iOptron iPolar scope/camera do for an Ekos user?

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Now, I love the idea of the iPolar -- calibrate it once, and then just go directly to alt-az adjustment every time you set up, no three images, no slewing, do not pass go, just turn the thing on and center the dot. Brilliant!

But AFAIK you have to use iOptron's app, which is only available for Windows and (sort of?) the Mac.

Seems to me I'm a lot better off with iOptron's nice polar scope, which has, what, a two-degree FOV? Even if I just get Polaris somewhere in view and don't bother to align it, I should be close enough for the Ekos PA Assistant. Without the magic live-red-dot software, the iPolar is just making it harder to get the scope rough-aligned to start with.

Am I wrong?
1 year 11 months ago #64028

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If you can use it to capture with EKOS, then it should be compatible with the PAA I would think.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
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Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
1 year 11 months ago #64031

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For what it's worth, I use Ekos for all my imaging, I have the iPolar on my CEM40, and I really like it.

All my imaging is done with KStars/Ekos on a R Pi running ubuntu. I control and monitor from indoors on a laptop (mine's a MacBook Pro).

But when I set up I just carry the laptop out to the mount and do my polar alignment in iPolar on the Mac. It literally takes less than a minute. The iPolar USB port is separate from the one that Ekos uses to control the mount. There's no cross talk. Ekos and the Pi doesn't even know the iPolar and the Mac are there. Just a quick mechanical tweak to the polar axis while watching the little circle line up on the little cross on my laptop screen. Then I unplug the mac and go back inside to let the pi and Ekos do their thing.

Personally I think this is a great setup. I used to run iPolar in Windows (under Parallels on the mac), but now the mac app is updated and works fine.
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1 year 11 months ago #64032

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Yes, but it provides no advantage. My ASI183MM is compatible with the PAA too!
1 year 11 months ago #64033

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That's useful data. I guess I'm not sold that it's that much more convenient than the Ekos PAA. I have to push a couple buttons on the screen, but it does its shoot-slew-shoot-slew-shoot thing and then I have essentially the same mechanic -- a live display with a target that I put the dot on by fiddling with the alt-az adjustments.

Now, you're actually using it, which is worth several times what my imagination is, to be sure! Is it really that much slicker than the Ekos PAA? I mean, I get that you don't have to wait for slews and solves, but with the new StellarSolver that's like ten seconds total in solving and maybe 30 seconds shooting and slewing. But if you say it's better, I'll believe you!
Last edit: 1 year 11 months ago by Rick Wayne.
1 year 11 months ago #64034

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I have only used the Ekos PAA a couple of times more than a year ago, so I can't really say iPolar is better. Sure works great though and doesn't conflict with Ekos in any way.

What you say makes sense though. Why pay for iPolar if you don't want it?
1 year 11 months ago #64035

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I use an iPolar on two iOptron mounts. With both we found a difference of 40’ when doing the polar alignment using the iOptron mount vs using Ekos. Have you ever checked with Ekos if it agrees with the Windows/Mac app?
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
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1 year 11 months ago #64040

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Holy cow! Now the 6 million dollar question jumps to mind: Which was correct, Ekos or the iPolar? I know I've had issues getting my PA to converge using Ekos (rerun the sequence and the alignment is still off or worse), and other times when I've gotten repeatable, single-digit arcseconds results with Ekos PAA, I run the PHD guiding assistant it tells me I have several minutes of error. Unfortunately I'm rarely in a position, or have the patience, to do a real live drift alignment to be certain.
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1 year 11 months ago #64065

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Any of these "one point" polar alignments are likely "wrong" by up to a few minutes of arc relative to the *effective* (refracted) pole that will optimally compensate for field rotation and DEC drift across the sky. That's a key advantage of mount modeling like TPoint or 10Micron.

Think of a polar scope, the Ekos/Sharpcap routines, or the iPolar program as a quick and simple approximation.

Drift alignment in PHD2 is going to be better, but is still just a sample of the many possible measurements.

The "best" position of the polar axis for long-exposure imaging will be given by optimizing a mount model against dozens to hundreds of measurements across as much of the sky as possible. But for most applications the quick-and-dirty methods work just fine.
Last edit: 1 year 11 months ago by Scott Denning.
1 year 11 months ago #64068

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I wasn't referring to PHD's drift alignment routine, actually, but to the process of observing DEC drift directly. If you can't detect any over the an interval similar to what you're using to image, well, pretty much axiomatically your alignment is good enough for imaging.

Wouter, I'm not sure I read your post correctly. Did you intend to say 40 minutes of arc? If it were 40 seconds I'd be intrigued, but probably shrug it off. 40 minutes...that's some real Tennessee windage you're talkin', there!
1 year 11 months ago #64069

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Yes I meant 40 arc minutes. We see it on two different mounts so it is hard to believe its a misalignment of the polar scope.

Wouter
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
1 year 11 months ago #64075

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I would think that it is practically impossible to get exact alignment with the iPolar in a single step the way it has been described above. That would require that the mount is a) perfectly level and b) the counterweight shaft is in exactly the same position every single time.
Even with the best level, I don't see it being possible to level out the mount to <30' accuracy. In the end, you would spend a LOT more time trying to level out the mount to the required accuracy than the rotations in Ekos take.
I don't even level out my mount anymore, I have it roughly level and let the PA routine do the rest.
I routinely end up with <2' PA accuracy using a polemaster (with the Ekos PA routine) and that is borne out by the drift analysis I can retrieve from the PHD2 log file at the end of the session (although I am not using PHD2, but exclusively the internal guider).

Jo
Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
1 year 11 months ago #64080

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