Date   

Re: Focus repeatability issue

Barry Megdal
 

The comments other have made about CFZ (Critical Focus Zone) are very relevant.  You need to find out what the step size of your focuser means in actual linear distance (e.g. microns), to see if the variation you are observing is even an issue.

 

Don Goldman and I wrote an article for Sky and Telescope (https://www.dropbox.com/s/j0iqk7026yfgklg/get%20focusedfinal.pdf?dl=0 ) a number of years ago which calculated a new, more restrictive definition of the CFZ, but once you know the step size and the optical parameters of your scope you can see if this variation is even an issue – Focusmax or other focusing software will always show some variation – the question is just whether it is significant.  The difference between what we published and the traditional definition of CFZ was that we showed that the traditional definition was roughly equivalent to a ¼ wave error, but 1/10 wave is more appropriate for critical imaging, so that is what I used in doing the math.

 

-        Barry

 

Dr. Barry Megdal

 

President

Shb Instruments, Inc.

19215 Parthenia St.  Suite A

Northridge, CA 91324

www.shbinstruments.com

(818) 773-2000  (818)773-2005 fax

bmegdal@...

 

Faculty (retired)

Dept. of Electrical Engineering

Caltech

 


Re: Setting AP1600 limits in remote obs

Michael Hambrick <mike.hambrick@...>
 

Do you have cameras in your observatory so that you can watch the scope ? The GoPro cameras are pretty high quality. You would probably need them looking at the scope and pier from at least two angles. Then you could watch everything while slewing the scope to the limits that you are comfortable with.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


Re: Setting AP1600 limits in remote obs

Roland Christen
 

Limits should definitely be used in any remote situation. They can be set in APCC remotely if you have an internet connection.

You also need to set up APCC so that the mount will automatically stop tracking in the case the computer connection is lost.

We are presently working on new software for the CP4/5 controllers that places limits internally into the controller, o even if everything external fails, the mount will still stop tracking at the internal limit point.

Rolando



-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 23, 2020 12:05 pm
Subject: [ap-gto] Setting AP1600 limits in remote obs

Hi everyone

I'm wondering how you set your ap mount limits when you can't access your mount? 

I'm thinking meridian limits and absolute limits (i.e., so it doesn't crash into the pier)



We have a 1600 GTOCP4 with absolute encoders and use APCC pro. it's on a pier in Chile (obstech) so we can't physically be there or see it. 

If necessary, we can ask someone to move it around and use the software, but they may not be familiar with using APCC. 

So far it hasn't been an issue because we've been doing light imaging and watching things, but we're moving into automation 

--
Brian 



Brian Valente


Re: Setting AP1600 limits in remote obs

Dale Ghent
 

I would do it interactively with obstech staff on the phone/voice chat. You move the mount, or they do with the hand controller, and they tell you when things are however close enough to the pier and you then record those limits yourself. They’re pretty smart folks there and they’ve probably been through this kind of exercise before. 

On Jun 23, 2020, at 13:05, Brian Valente <bvalente@...> wrote:


Hi everyone

I'm wondering how you set your ap mount limits when you can't access your mount? 

I'm thinking meridian limits and absolute limits (i.e., so it doesn't crash into the pier)



We have a 1600 GTOCP4 with absolute encoders and use APCC pro. it's on a pier in Chile (obstech) so we can't physically be there or see it. 

If necessary, we can ask someone to move it around and use the software, but they may not be familiar with using APCC. 

So far it hasn't been an issue because we've been doing light imaging and watching things, but we're moving into automation 

--
Brian 



Brian Valente


Re: Point Mapping Strategies for the Mobile Imager

Dean Jacobsen
 

Thanks Michael.

It is a little bit of personal preference and a little bit because of the configuration inside the observatory.  You can't see them but there are four piers in there.  There is a big CDK 12.5 just to the north-west of me and there is probably less than 12" of clearance between us when he has his scope pointing west and I am pointing east.  Our mains power outlets are on the south wall and that is what I am plugged into.  The backup battery sits at the base of the pier on the west side.  If I set up the computer table on the south side then I have less cable strung across the floor and I keep the center area of the observatory a little more open so everyone can get around in the dark easier.   
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Setting AP1600 limits in remote obs

 

Hi everyone

I'm wondering how you set your ap mount limits when you can't access your mount? 

I'm thinking meridian limits and absolute limits (i.e., so it doesn't crash into the pier)



We have a 1600 GTOCP4 with absolute encoders and use APCC pro. it's on a pier in Chile (obstech) so we can't physically be there or see it. 

If necessary, we can ask someone to move it around and use the software, but they may not be familiar with using APCC. 

So far it hasn't been an issue because we've been doing light imaging and watching things, but we're moving into automation 

--
Brian 



Brian Valente


Re: Point Mapping Strategies for the Mobile Imager

Michael Hambrick <mike.hambrick@...>
 

Very nice, but I see a serious problem with the new version: The roof is closed :>)

All kidding aside I do have a dumb question. In the original version you had your workspace (desk & laptop) on the south side of the pier. Is there one particular location for the workspace that is better than another (N-S-E-W), or is it mostly a matter of personal preference ?


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


Re: Point Mapping Strategies for the Mobile Imager

Dean Jacobsen
 

Thanks Roland and Charles!  The mount and software package that the AP team has put together is super nice.  Everything has worked flawlessly.
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Point Mapping Strategies for the Mobile Imager

Charles Thompson
 

Very clean implementation Dean!





Thanks,
Charles

Sent from mobile device.


-------- Original message --------
From: Dean Jacobsen <deanjacobsen@...>
Date: 6/23/20 11:36 AM (GMT-06:00)
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Point Mapping Strategies for the Mobile Imager

... and finally, the Mach2 + scope has a new look.  No guiding apparatus.

https://www.astrobin.com/yqzal0/C/
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Point Mapping Strategies for the Mobile Imager

Roland Christen
 

Post that on CN and watch them drool ;^))

Rolando Stuck out tongue closed eyes



-----Original Message-----
From: uncarollo2 <chris1011@...> via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Jun 23, 2020 11:38 am
Subject: Re: [ap-gto] Point Mapping Strategies for the Mobile Imager

Clean as a whistle! (or hound's tooth?).

Rolando

-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 23, 2020 11:36 am
Subject: Re: [ap-gto] Point Mapping Strategies for the Mobile Imager

... and finally, the Mach2 + scope has a new look.  No guiding apparatus.

https://www.astrobin.com/yqzal0/C/
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Point Mapping Strategies for the Mobile Imager

Roland Christen
 

Clean as a whistle! (or hound's tooth?).

Rolando

-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 23, 2020 11:36 am
Subject: Re: [ap-gto] Point Mapping Strategies for the Mobile Imager

... and finally, the Mach2 + scope has a new look.  No guiding apparatus.

https://www.astrobin.com/yqzal0/C/
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Point Mapping Strategies for the Mobile Imager

Dean Jacobsen
 

... and finally, the Mach2 + scope has a new look.  No guiding apparatus.

https://www.astrobin.com/yqzal0/C/
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Focus repeatability issue

Dale Ghent
 

Are you sure it was truly clear sky where you had your telescope pointed? Faint high-level clouds can affect the measured HFD/HFR of the star(s) that MaximDL is using. Clouds move, and that could explain the quickly varying values you are getting.

Also consider the resolution of your setup - a single step in your case might be quite small so the CFZ in your case might /seem/ wide because the high resolution of your setup puts a lot of steps in that zone and landing anywhere in that zone will be ok.

It is tough to find exacting repeatability when creating focus offsets in any system simply due to mechanical and atmospheric effects. The CFZ is always going to be more than 1 single step, so my recommendation is do do a run and then use those derived offsets and look for the repeatability of the HFD/HFR values those produce. If they seem consistent and your stars look good, then you have good offsets to work with.

/dale

On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@gmail.com> wrote:

I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha. If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.

The other filters behaved similarly. I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.

Any ideas on what I should look for to determine source of this erratic behavior?
The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched. Seeing?

Thanks in advance,
Jim



Re: Focus repeatability issue

Stuart <stuart.j.heggie@...>
 

Jim, I am wondering if what you're seeing is that the scope is still cooling and the optics and tube are still changing shape. Just because the outside temps are stable does NOT mean that the scope is thermally stable too.

If I were to do this experiment, I would opt to do it in the pre-dawn hours on a night that has a very stable temperature. Otherwise what you may be seeing is the ambient is stable the scope is catching up.


On Tue, 23 Jun 2020 at 10:40, Jim Fakatselis <pashasdad@...> wrote:
Interesting...
I live on Long Island in NY.  
Jim


On Jun 23, 2020, at 10:14 AM, Michael Hambrick via groups.io <mike.hambrick=arlanxeo.com@groups.io> wrote:

It could be due to variation in the seeing. I have been wanting to ask the experts on the forum what they are actually looking at when they talk about seeing in terms of arc seconds, and how they measure it.

Where are you imaging from ? I have also been watching on the weather reports where they have been saying that there is a very prominent Saharan dust cloud moving west and is already affecting the southern parts of the US (Florida & Gulf Coast states). I expect that this dust will degrade the quality of the seeing. I guess the good news is that it reduces the chances of tropical cyclone formation.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Jim Fakatselis" <jfakatse@...>
To:        main@ap-gto.groups.io
Date:        2020-06-23 09:06 AM
Subject:        Re: [ap-gto] Focus repeatability issue
Sent by:        main@ap-gto.groups.io




Here’s the tabular data.

<mime-attachment.jpg>

On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:



I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  


Any ideas on what I should look for to determine source of this erratic behavior?

The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim




--

Stuart
http://www.astrofoto.ca/stuartheggie/


Re: Focus repeatability issue

Roland Christen
 

I don't believe seeing has any effect on focus position. Temperature has the most effect. The aluminum tube shrinks with falling temps and optical lenses also change focal position with dropping temps. During that time the focus position can vary considerably, so you may have to refocus after every frame until the air temperature stabilizes or drops at a slower rate.

Rolando

-----Original Message-----
From: Jim Fakatselis <pashasdad@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 23, 2020 10:00 am
Subject: Re: [ap-gto] Focus repeatability issue

I would generally expect seeing effects to be more random in nature not as monotonous but I may be incorrect.  Not much experience.  

On Jun 23, 2020, at 10:40 AM, Jim Fakatselis via groups.io <pashasdad@...> wrote:


Interesting...
I live on Long Island in NY.  
Jim


On Jun 23, 2020, at 10:14 AM, Michael Hambrick via groups.io <mike.hambrick@...> wrote:

It could be due to variation in the seeing. I have been wanting to ask the experts on the forum what they are actually looking at when they talk about seeing in terms of arc seconds, and how they measure it.

Where are you imaging from ? I have also been watching on the weather reports where they have been saying that there is a very prominent Saharan dust cloud moving west and is already affecting the southern parts of the US (Florida & Gulf Coast states). I expect that this dust will degrade the quality of the seeing. I guess the good news is that it reduces the chances of tropical cyclone formation.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Jim Fakatselis" <jfakatse@...>
To:        main@ap-gto.groups.io
Date:        2020-06-23 09:06 AM
Subject:        Re: [ap-gto] Focus repeatability issue
Sent by:        main@ap-gto.groups.io




Here’s the tabular data.

<mime-attachment.jpg>

On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:


I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.
I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.
The other filters behaved similarly.  I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  


Any ideas on what I should look for to determine source of this erratic behavior?

The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim



Re: Focus repeatability issue

Jim Fakatselis
 

I would generally expect seeing effects to be more random in nature not as monotonous but I may be incorrect.  Not much experience.  

On Jun 23, 2020, at 10:40 AM, Jim Fakatselis via groups.io <pashasdad@...> wrote:


Interesting...
I live on Long Island in NY.  
Jim


On Jun 23, 2020, at 10:14 AM, Michael Hambrick via groups.io <mike.hambrick@...> wrote:

It could be due to variation in the seeing. I have been wanting to ask the experts on the forum what they are actually looking at when they talk about seeing in terms of arc seconds, and how they measure it.

Where are you imaging from ? I have also been watching on the weather reports where they have been saying that there is a very prominent Saharan dust cloud moving west and is already affecting the southern parts of the US (Florida & Gulf Coast states). I expect that this dust will degrade the quality of the seeing. I guess the good news is that it reduces the chances of tropical cyclone formation.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Jim Fakatselis" <jfakatse@...>
To:        main@ap-gto.groups.io
Date:        2020-06-23 09:06 AM
Subject:        Re: [ap-gto] Focus repeatability issue
Sent by:        main@ap-gto.groups.io




Here’s the tabular data.

<mime-attachment.jpg>

On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:



I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  


Any ideas on what I should look for to determine source of this erratic behavior?

The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim




Re: Focus repeatability issue

Jim Fakatselis
 

Interesting...
I live on Long Island in NY.  
Jim


On Jun 23, 2020, at 10:14 AM, Michael Hambrick via groups.io <mike.hambrick@...> wrote:

It could be due to variation in the seeing. I have been wanting to ask the experts on the forum what they are actually looking at when they talk about seeing in terms of arc seconds, and how they measure it.

Where are you imaging from ? I have also been watching on the weather reports where they have been saying that there is a very prominent Saharan dust cloud moving west and is already affecting the southern parts of the US (Florida & Gulf Coast states). I expect that this dust will degrade the quality of the seeing. I guess the good news is that it reduces the chances of tropical cyclone formation.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Jim Fakatselis" <jfakatse@...>
To:        main@ap-gto.groups.io
Date:        2020-06-23 09:06 AM
Subject:        Re: [ap-gto] Focus repeatability issue
Sent by:        main@ap-gto.groups.io




Here’s the tabular data.

<mime-attachment.jpg>

On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:



I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  


Any ideas on what I should look for to determine source of this erratic behavior?

The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim




Re: Focus repeatability issue

Michael Hambrick <mike.hambrick@...>
 

It could be due to variation in the seeing. I have been wanting to ask the experts on the forum what they are actually looking at when they talk about seeing in terms of arc seconds, and how they measure it.

Where are you imaging from ? I have also been watching on the weather reports where they have been saying that there is a very prominent Saharan dust cloud moving west and is already affecting the southern parts of the US (Florida & Gulf Coast states). I expect that this dust will degrade the quality of the seeing. I guess the good news is that it reduces the chances of tropical cyclone formation.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Jim Fakatselis" <jfakatse@...>
To:        main@ap-gto.groups.io
Date:        2020-06-23 09:06 AM
Subject:        Re: [ap-gto] Focus repeatability issue
Sent by:        main@ap-gto.groups.io




Here’s the tabular data.


On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:



I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all.
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example.

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp.

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  


Any ideas on what I should look for to determine source of this erratic behavior?

The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim




Re: Focus repeatability issue

Jim Fakatselis <jfakatse@...>
 

Here’s the tabular data. 


On Jun 23, 2020, at 9:53 AM, Jim Fakatselis <pashasdad@...> wrote:



I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all. 
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example. 

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp. 

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  

Any ideas on what I should look for to determine source of this erratic behavior?
The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim


Focus repeatability issue

Jim Fakatselis
 

I am imaging with a QSI683WS8 and a Starlight Instruments focuser with the Starlight stepper motor on an AP130mm EDF refractor Using MaximDL.

I was attempting to measure the filter offsets with my AstroDon series E gen 2 filter set. Taking four sets of measurements repeatedly with 5 of the 7 filters I use most, L, R,G,B,Ha.  If I try to immediately refocus, my focus setting continues to drift monotonically. Very erratically. Can’t get repeatability at all. 
This past evening four V curve runs on just the Luminance filter in rapid succession, (less than 2-3 min per V curve), over and over produced readings like this:
15020, 15101, 15140, 15213 as an example. 

The other filters behaved similarly.  I can provide Excel plot of data with linear ramp. 

Reported temp from HSM stepper is well within 1 deg, measurements were made about 2-3 min apart in rapid succession. Little to no temp effect should be present.  

Any ideas on what I should look for to determine source of this erratic behavior?
The last few weeks there has not been an issue like this, this seemed to develop suddenly. No change to imaging train, it’s been untouched.   Seeing?

Thanks in advance,
Jim

7681 - 7700 of 79015