Grimsrudjk wrote: I’ll record the log the next I’m out with it. My options are “Sync”, “Slew to Target”, and “Nothing”. I’ve got the “Sync” option checked. Is that the correct mode to be in?

Jake,

Synch will only tell the mount where you are pointing.

There are two things you need to do

1) Choose and slew to a target and then.
2) Run plate solving with the Slew to Target option.

When you do this it will iterate as many times as required until it is within your configured accuracy - I use 30 arc seconds,

Regards

Paul

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Grimsrudjk wrote: Hey folks,

I’m not sure how to put this - I’ve spent the last 6 months just trying to get ASTAP to successfully solve one of my images. Tonight, I finally fixed that problem and ran face first into another problem.

I can success plate solve, and the software shows that the coordinates have successfully synced to the mount. But no matter how many iterations of plate solving I do, my position error never gets better than 20,000 arcseconds, which is totally unusable. I’m picking targets all over the sky away from the meridian, but it never gets any better. Does anyone have any suggestions?


Jake,

You will need to provide some log files.

There are three options with solving, synch, slew to and nothing, are you sure it has slew to set?

Paul

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After a period of cloud I have now been able to collect more evidence of what is happening.

Please note that whenever I manually select the star to use for focusing, it works correctly, it is only ever an issue when using autoselect.

There seems to be two main circumstances -
1) It selects a star and centres it but then uses another star in the subframe to focus on. This sometimes involves two stars close together where it jumps back and forward between them.
2) It selects a star but instead of being centred in the subframe it is near the edge. This sometimes work fine but sometimes slips outside the frame while focusing.

The three examples attached
1) Selected two stars close together - nothing apparent in the center
2) Right on the edge
3) Plenty of stars in full frame but nothing in subframe
4) Star in centre but using one near the edge



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Paul replied to the topic 'Focus difficulties with ZWO EAF' in the forum. 2 months ago

shinken wrote: Hi,

I've been working out autofocus with my ZWO EAF + ZWO ASI183GT + TS 76EDPH scope but I am having some issues.

1. Algorithm: I have tried many combinations. Autoselect start and subframe works fast using SEP and iterative and works well while I am paying attention and manually start from a good rough focus but left alone during an automated sequence it fails. Full field seems to work better when left alone with a step of 25 if focus is close to correct but sometimes it goes off in the wrong direction, loses focus then fails to detect stars (because of going completely out of focus) and it aborts the sequence. Any suggestions as to what algorithm, initial step size, etc.?

Thanks in advance for your help.


Shinken,

I cannot be certain, but this may be due to the same issue I have been looking into in the link below. The autofocus chooses a star and creates a subframe around it but then sometimes uses another star in the subframe to perform the autofocus on, which can fail. If you are not watching it happen you just find it has lost focus.

Autofocus changing to another star to perform the autofocus

Paul

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mhammady wrote: IMO this could be one of three possibilities (as it happened to me before), (1) you are not physically tracking, i mean you set tracking to ON and see position change, but the mount is not moving as it was ordered, or (2) you are don't have good polar alignment and the tracking is way off course, or (3) tracking for stars is not sidereal.

Technically, if the polar alignment is accurate, and the mount is tracking good (either on its own or controlled by ekos), you should see your target standstill, regardless of what you are doing with your camera. Guiding is for minor correction for astrophotography, but here you are just checking for fucus for 2-sec shots. You should have the stars stationary for a some time.

One further thing to higlight is that this is only an issue when using autoselect.
If I select if manually it works fine, so I cannot see this has anything other than to do with the autoselect routines.

Paul

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mhammady wrote: IMO this could be one of three possibilities (as it happened to me before), (1) you are not physically tracking, i mean you set tracking to ON and see position change, but the mount is not moving as it was ordered, or (2) you are don't have good polar alignment and the tracking is way off course, or (3) tracking for stars is not sidereal.

Technically, if the polar alignment is accurate, and the mount is tracking good (either on its own or controlled by ekos), you should see your target standstill, regardless of what you are doing with your camera. Guiding is for minor correction for astrophotography, but here you are just checking for fucus for 2-sec shots. You should have the stars stationary for a some time.

This is not going to be a tracking issue.
The star used to select the subframe is exactly centred, it is just that it is not being used to do the select.
Polar alignment is accurate, and I have not adjusted it for nearly 12 months, I am able to do 20 minute exposures with no issues. It was drift aligned using PHD2.
It changes tracking speed if I choose the Sun or Moon but stars use siderial.
Paul

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Croz wrote: I wonder if this is the same issue I’m running into? I’m using the full frame and multi star. But it sounds similar.

indilib.org/forum/general/7947-sep-autof...-star-detection.html

It is possible.
First of all it appears to be prone to selecting multiple stars or globulars to focus on and I have also found that it sometimes selects an area devoid of stars.
In my experience it appears the initial selection that is used to create the subframe is too often fooled by small globulars and multiple stars but they can still be used to focu, even though it takes longer.
The major part of my issue, and one that does not happen all the time, is the star that is initially selected is not being used to perform the focus, it seems to decide to use another even though the original star is centred in the subframe. Another hint is that on occassion the square is a rectangle, which leads me to believe a variable is being corrupted.
This seems to have been introduced sometime in the last 6-12 months.

Paul

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xthestreams wrote: Fascinating! Well it's not mirror flop then!

Could you screen shot your settings and share - this is interesting!


I could not completely duplicate this last night but have some interesting results.

First image is a first attempt and worked. Notice that the selected area is square.
The next image shows a later attempt which also also worked but notice that the selected area has become a rectangle.
The next image is another attempt that shows a selection problem. The area is again a square and it has chosen an area around a valid star but has selected what I recall was actuall two stars away from the centre. It was actually able to focus using them, but is not ideal the central star was probably the best to focus on and must have been what was used to define the square.
The fourth image clearly shows two stars selected which are not the centred star.
The final three images show some of the settings.

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mhammady wrote: Try the full field option with 15% & 55% as annular values, and see if your problem is resolved.


I understand that full frame is an option but as it takes around 30-45 seconds to download a Frame it is a slow process to use it.

My preference is to find out what is going on with the subframe, which works well and quickly so long as I manually select the star. Obviously this impacts on my efforts to automate things.

Paul

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mhammady wrote:

phomer60 wrote: I am reasonably confident this is not a Mount issue as it only happens with the autofocus.
The only time I turn off tracking is when the mount is parked.
It is a Losmandy G11 with Gemini 2.




when I have something like that (keep loosing the focus star especially outside the green box with subframes), I start guiding before focusing. It helps retain the star in the green box. Also, I use a 64-bit box size just in case.


Guiding must be turned off while focusing as I am using off-axis guiding.

The problem is not that the star moves away from the centre, it is never in the centre in the first place, it is selected and positioned on the edge of the subframe it does not move to the edge.

Paul

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xthestreams wrote: Fascinating! Well it's not mirror flop then!

Could you screen shot your settings and share - this is interesting!


I will get some screen shots but it may be a while although there may be gap in the weather Friday night.

Clear skies are a rarity at the moment so my main priority has been to get some images, so I immediately go and manually select a star.

Paul

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