ASI Air Issues - Too few stars and not plate solving - mysteriously fixed

[Sarek]

Normally I have had no issues with getting my ASI Air mini up and running for plate solving, polar aligning and guiding but tonight for no obvious reason it just wouldn't play ball for over an hour.  I was reluctant to start fiddling around with settings as they have been working for me perfectly up until tonight. Eventually after resetting it several times, turning the whole rig  off and on it started to work. Some of the issues:

- Not plate solving - too few stars reported

- On attempting Polar Aligning reporting not picking up enough stars again ( eg less than 10) yet the preview showed plenty and the skies were clear

I have not changed anything that I am aware of since my last session last week. 

I focused as tightly as I could using a bahtinov mask as I usually do

I used the same exposure time in preview that I always do - 3 seconds

I double checked the focal lengths for each camera had not changed

I had gain set at 101 for main camera (ASI 533MCPro) and 37 for guide camera (ASI 120MM Mini).

I even tried changing the 2 around so the guide camera was the main camera and the 533 the guide but again exactly the same issue with too few stars being reported.

I don't know if this is relevant but I noticed the polar alignment steps seem to have changed - it used to rotate 60 degrees on first step but now it seems to rotate varying degrees (10-20 from memory) in 3 steps plate solving after each - is that because of a recent software update?

I'm sat here now in the middle of an imaging session and it's all working perfectly - even though its windy my guiding is holding steady around 0.7 rms.  Just intrigued to know what might have caused my earlier problems and if there is an underlying issue that might come back to bite me on a more permanent basis.

 

 

 

 

 

[bosun21]

How was your supply voltage? Any loose connections? When I used the plus it always did two movements in polar alignment. First plate solve then about 20-25° and finally about 50-55°. The all sky polar align only does the two.

[Budgie1]

My ASIAir Mini does 3 movements on PA and as many as it takes to correctly plate solve (there is no specific number for this as it's relying on the accuracy of the mount).

The only thing I can think of is possible fogging of the camera window or the scope lens, due to cooling. This would then clear as the temperature equalised or dew heaters started working.

You could try a higher gain for PA. plate solving & focusing, as you can set the gain you want for the image run in the planner.

[Sarek]

Thanks Ian. I did check connections which seemed ok but maybe some were a bit loose. I did reseat them all at one point but that didn't do the trick. I've got an external power socket so the voltage should be normal.

Edited December 10, 2023 by Sarek

[Sarek]

9 minutes ago, Budgie1 said:

My ASIAir Mini does 3 movements on PA and as many as it takes to correctly plate solve (there is no specific number for this as it's relying on the accuracy of the mount).

The only thing I can think of is possible fogging of the camera window or the scope lens, due to cooling. This would then clear as the temperature equalised or dew heaters started working.

You could try a higher gain for PA. plate solving & focusing, as you can set the gain you want for the image run in the planner.

Thanks - I think the 3 movements were related to the lack of reported stars then?

I will try a higher gain next time this happens.

I had dew heaters on both guide and main scope. I have not tried a  dew heater on the  ASI 533mc Pro as I believe its not required?

[Budgie1]

41 minutes ago, Sarek said:

Thanks - I think the 3 movements were related to the lack of reported stars then?

Sorry, I was getting myself confused. The Polar Alignment routine normally takes three positional readings, one at what ever position the mount is starting in, then moves around 30°, plate solves, then moves another 30°, plate solves again and calculates the RA & DEC corrections. It's from this position that you make any corrections.

If yours did three positional moves, then it could have been related to the lack of detectable stars.

47 minutes ago, Sarek said:

I had dew heaters on both guide and main scope. I have not tried a  dew heater on the  ASI 533mc Pro as I believe its not required?

Normally you put the dew heaters on the scopes only, but you can get a heater (LINK) for the ZWO cameras, for use if you're getting fogging on the camera AR window. If you're not seeing this then don't bother with it.

You can also get condensation forming on the camera sensor, this is seen on the images as dots or misting in the centre of the image. The cure for this is recharging or changing the desiccant tablets inside the camera. Again, if you're not seeing this then don't bother with it because it means taking the front of the camera body off and exposing the sensor to possible dust! 

[Elp]

I think you may have answered you own question with the last comment. Was it windy when PA?

[Elp]

Also the two/three step PA is fairly new, I've been using airs for three years and still use 1.9 beta app, PA does 60 degree rotation in one step and it has been like this from the beginning until now.

[Sarek]

11 minutes ago, Budgie1 said:

Sorry, I was getting myself confused. The Polar Alignment routine normally takes three positional readings, one at what ever position the mount is starting in, then moves around 30°, plate solves, then moves another 30°, plate solves again and calculates the RA & DEC corrections. It's from this position that you make any corrections.

If yours did three positional moves, then it could have been related to the lack of detectable stars.

Normally you put the dew heaters on the scopes only, but you can get a heater (LINK) for the ZWO cameras, for use if you're getting fogging on the camera AR window. If you're not seeing this then don't bother with it.

You can also get condensation forming on the camera sensor, this is seen on the images as dots or misting in the centre of the image. The cure for this is recharging or changing the desiccant tablets inside the camera. Again, if you're not seeing this then don't bother with it because it means taking the front of the camera body off and exposing the sensor to possible dust! 

Thanks Martin.

As it happens my camera (which I picked up second hand) does have a heating strip fitted but I've never used it. I'm pretty sure there was no fogging/misting this evening but definitely something I'll look out for in future.

[Sarek]

1 minute ago, Elp said:

Also the two/three step PA is fairly new, I've been using airs for three years and still use 1.9 beta app, PA does 60 degree rotation in one step and it has been like this from the beginning until now.

Yes, mine has always done 60 degrees in one step until this evening

[Sarek]

4 minutes ago, Elp said:

I think you may have answered you own question with the last comment. Was it windy when PA?

Maybe that's it then because it was VERY windy for a while

[Elp]

You haven't mentioned if you're using filters. The only time mine fails to plate solve is during the following:

1. Filter, usually O3 is a particularly difficult one to use (it's easier to PA without filter then insert filter and refocus after) but sometimes I do it with filter to save setup time, exposure time for plate solving needs to be increased in such situations.

2. Using an uncooled camera but not relevant here, but this detects lots of stars due to added sensor noise.

3. Unfocused, you can PA with a small amount of unfocused star bloat but not too much.

[Elp]

2 minutes ago, Sarek said:

Maybe that's it then because it was VERY windy for a while

It's so windy I didn't bother setting up, you generally learn via experience what wind gust level is acceptable, even short subs tonight will have been extremely difficult if not set up in an observatory type walled off on four sides setup.

[Sarek]

24 minutes ago, Elp said:

You haven't mentioned if you're using filters. The only time mine fails to plate solve is during the following:

1. Filter, usually O3 is a particularly difficult one to use (it's easier to PA without filter then insert filter and refocus after) but sometimes I do it with filter to save setup time, exposure time for plate solving needs to be increased in such situations.

2. Using an uncooled camera but not relevant here, but this detects lots of stars due to added sensor noise.

3. Unfocused, you can PA with a small amount of unfocused star bloat but not too much.

I'm using an L eXtreme filter this evening

Pretty sure my focusing was good - using a Bahtinov mask.  I'm gettting good data now and not changed it.

[Sarek]

30 minutes ago, Elp said:

It's so windy I didn't bother setting up, you generally learn via experience what wind gust level is acceptable, even short subs tonight will have been extremely difficult if not set up in an observatory type walled off on four sides setup.

Yes it was very windy for a while with some very strong gusts.  My rig is set up close to the house so I thought it might be ok but perhaps not. As you say, another learning experience

[StevieDvd]

There's an old software testers trick that might explain your issue.

When software is updated it may need to adjust any config files and write the default values that are read at start up.  The coder may only do this on the first change to the config or on a restart (hence the restarts you see systems do so often) so until a change is made the system can exhibit odd behaviour. You, changing the cameras, may have effected the update to the config solving the problem (which should not happen).

Bane of my life in testing were coders who never initialised their variables but read them later in their code  - my test software would catch them and the coder would be put on the wall of shame list. 😒