My HEM15 has arrived

[Ags]

We don't need to add to the reasons not to observe 😄 

I'll stay away from the C6 on the more brisk evenings! Maybe I need a more aerodynamic option for the gusty nights, like a 50 mm refractor!

[Elp]

You know you want to...

[Ags]

I thought this was an ok result, shot over two evenings using the Air's ability to goto a picture you took the previous evening. This is under Bortle 8 skies.

[Ags]

Nah, that was a rubbish result! Tried again making sneaky use of Siril photometric color calibration this time. The galaxy is a bit orange now, but the stars are more colorful 😀

...third time's the charm....

Edited March 12 by Ags

[Ags]

I am having no luck plate solving with the ASI485MC and my RC6 (reduced to a focal length of about 900 mm. The short side of the chip should still span around 0.4 degrees so it should be possible.

[happy-kat]

have you tried sharpcap sharpsolve and the .25 database

[Elp]

1 hour ago, Ags said:

I am having no luck plate solving with the ASI485MC and my RC6 (reduced to a focal length of about 900 mm. The short side of the chip should still span around 0.4 degrees so it should be possible.

What does the starfield exposure preview look like? You can try increasing the exposure length duration to see if it resolves more stars, an uncooled camera if not saturating the stars enough can mistake noise for stars or fail to plate solve completely, also ensure no LP glare is on the exposure (take a test image in preview mode to see what it looks like, you can also plate solve from that preview).

 

 

[Ags]

I got plate solving working last night at a focal length of 970 mm. The trick was to plate solve in the AsiAir Preview mode, and then sync to the target. Plate solving during polar aligning and during object selection still refuses to work.

[Elp]

9 minutes ago, Ags said:

Plate solving during polar aligning and during object selection still refuses to work.

Is your imaging scope FL correctly specified? When you start the app or under the camera setting. If you don't know it exactly due to using corrective optics you can leave it set at zero mm on startup, when it plate solves either during PA or preview it'll work out and assign the FL automatically.

[Ags]

Yes, I have been setting to zero each time. The Air calculated 970 mm focal length when it eventually solved.

[Elp]

You've also changed the exposure time to 5 or 10s?

[Ags]

For polar aligning it is 5 seconds. Not sure where else to set it?

[Elp]

1 hour ago, Ags said:

For polar aligning it is 5 seconds. Not sure where else to set it?

https://bbs.zwoastro.com/d/13174-asiair-plate-solving-exposure-settings

[Ags]

Thanks @Elp! Yet again you have set me on the right path. I raised the plate solving exposure for polar alignment and GoTo to 10 seconds and it is working smoothly now. 

[Ags]

One thing that puzzles me is that the gotos require so much correction from plate solving. I am almost perfectly polar aligned, so why doesn’t the goto get close. With a regular go to, you expect the target to be somewhere in the field of a wide eyepiece, but the HEM15 and AIR  are not even close. Plate solving papers over the errors, but it is puzzling. 

[Elp]

Are you sure your location is set correctly on the hand controller and also the time in UTC time format with DST turned off? I find both my ioptrons are quite accurate with goto. A long focal length scope will need more adjustments as it's a smaller FOV so the slightest movement can make a big difference.

[vlaiv]

34 minutes ago, Ags said:

One thing that puzzles me is that the gotos require so much correction from plate solving. I am almost perfectly polar aligned, so why doesn’t the goto get close. With a regular go to, you expect the target to be somewhere in the field of a wide eyepiece, but the HEM15 and AIR  are not even close. Plate solving papers over the errors, but it is puzzling. 

How fast is your slew to position?

Looking at the specs - stepper motors could be quite a bit under powered. This can result in skipped steps at high slew speeds. Steppers loose their torque with higher RPMs and since this mount does not use counterweights - it instead relies on stepper motors to provide torque to keep the weight in position.

From specs - max amperage when slewing is 0.8A - that is very low, we can say that it uses probably 0.3A per motor (some of current for electronics and some for motors - two of them).

Anyway, it slews at max 6 degrees / second - with reduction ratio of 360:1.

That makes one whole revolution in 60 seconds - or 1 rpm, so motor needs to spin at 360 rpm.

Here is example of 0.4A Nema 17 motor showing dependence of torque to RPM - at 360rpm pull out torque is 1/10th that of slow speed (motor is rated at 26N/cm). This is with 24V and 1600 micro steps (or 1/8th micro stepping) - things get only worse with finer micro stepping and when using lower voltage to power motors - like 12V

Anyway - try setting slew speed to 1-2 degrees / second instead to see if that helps with goto accuracy.

[Ags]

21 minutes ago, Elp said:

Are you sure your location is set correctly on the hand controller and also the time in UTC time format with DST turned off? I find both my ioptrons are quite accurate with goto. A long focal length scope will need more adjustments as it's a smaller FOV so the slightest movement can make a big difference.

Unless I’m mistaken, the handset is irrelevant, all the thinking is done by the Air? To answer the question, I haven’t set up the handset at all…

[Ags]

19 minutes ago, vlaiv said:

Anyway - try setting slew speed to 1-2 degrees

I will try that!

[Elp]

32 minutes ago, Ags said:

Unless I’m mistaken, the handset is irrelevant, all the thinking is done by the Air? To answer the question, I haven’t set up the handset at all…

The handset is the "brain" of ioptron mounts. The air does the controlling but in hand with the information from the mount hand controller. As far as I know you can't use ioptron mounts without the hand controller when using an air so it must be needed for something.

Edited April 23 by Elp

[Ags]

I believe all the electronic stuff for the mount is in the handset… therefore you have to plug the air into the handset. But I’m pretty sure the handset isn’t feeding the Air any info. For example, the Air handles meridian flips perfectly, so it clearly knows where the scope is pointing relative to the ground.

I’ll test @vlaiv theory about skipped steps first. If that doesn’t work I will relent and set the handset. 😃

[Elp]

The air can mess up meridian flips if the time is not in UTC format on the hand controller. It's a common problem talked about within the ZWO forums.

[Ags]

Thanks for that, I dug out and installed a button battery and set the time and location. The location was already right, the Air must update this somehow as I never configured this and without a battery the handset would not remember anyway. Time zone was also right but time was out by an hour. DST setting was also wrong.

[Ags]

Now of course I have to babysit the setup through a few meridian flips as by attempting to fix the goto I might have broken the flips.

[Elp]

It never occurred to me to ask but for clarification how exactly did you use the hem15 with the air without the hand controller? The usb connection and WiFi are contained within the hand controller.