Info about 130GTX + 0.72x QuadTCC + ASI6200


sebkersten
 

Hi,

I use an ASI6200 camera for my deep sky photography. I have the opportunity to buy a 130GTX with the QuadTCC reducer.

I am looking for information and examples of images made with this material. I would like to see how the stars are in the corners of the image. Indeed, with the ASI6200, there is no tolerance.

For info, actually I us use a TOA130NFB and the TOA-35 reducer. The image circle is 44mm.
If in h-alpha, the elongation of the stars in the corners is acceptable, in luminance the deformation is too important.

That's why I'm looking to the 130GTX.

Thanks in advance for your help.

Sincerely

Sébastien


David
 

They’ll be fine. I have the same setup except it’s a 130GT. Corners are good with my QHY600.

David

On May 3, 2021, at 1:23 PM, sebkersten <sebastien.kersten@gmail.com> wrote:

Hi,

I use an ASI6200 camera for my deep sky photography. I have the opportunity to buy a 130GTX with the QuadTCC reducer.

I am looking for information and examples of images made with this material. I would like to see how the stars are in the corners of the image. Indeed, with the ASI6200, there is no tolerance.

For info, actually I us use a TOA130NFB and the TOA-35 reducer. The image circle is 44mm.
If in h-alpha, the elongation of the stars in the corners is acceptable, in luminance the deformation is too important.

That's why I'm looking to the 130GTX.

Thanks in advance for your help.

Sincerely

Sébastien








sebkersten
 

Hi David

Thanks for your advise.

Would you have some pictures to show me? This would be great.
Of, maybe, you could send me a single image (fit), via a Wtransfert or dropbox.

Thank you for your help

Sincincerely,

Sébastien

Le 3 mai 2021 à 21:36, David via groups.io <phrosty5=yahoo.com@groups.io> a écrit :

They’ll be fine. I have the same setup except it’s a 130GT. Corners are good with my QHY600.

David


On May 3, 2021, at 1:23 PM, sebkersten <sebastien.kersten@gmail.com> wrote:

Hi,

I use an ASI6200 camera for my deep sky photography. I have the opportunity to buy a 130GTX with the QuadTCC reducer.

I am looking for information and examples of images made with this material. I would like to see how the stars are in the corners of the image. Indeed, with the ASI6200, there is no tolerance.

For info, actually I us use a TOA130NFB and the TOA-35 reducer. The image circle is 44mm.
If in h-alpha, the elongation of the stars in the corners is acceptable, in luminance the deformation is too important.

That's why I'm looking to the 130GTX.

Thanks in advance for your help.

Sincerely

Sébastien












Malik AMZIANE
 

Hello all,
 
I was just going to open a discussion on this subject to seek the advice of Master Roland.
I received this week the focuser 3.5 to upgrade my AP130GT, in order to mount the QuadTCC on it.
I did 2 nights of testing with an ASI6200 and I can't manage to get perfectly picky stars in the corners.
 
I did about ten assemblies with different distances to 0.3mm and here is the best result I get.
 
I don't know if this is normal, if I have reached the maximum of what the Ap130/Quad combo can give. Or if I can still improve?
I had to adjust a slight tilt, and when I add or remove 0.5mm the field curvature increases.
For the settings I use CCDInspectore and ASTAP.
 
Maybe I am too demanding? The stars in the corners are not perfectly round but rather triangular.
 
I specify that before that I had mounted the QuadTCC on an LZOS 152F8, I managed to set the backfocus perfectly and I get perfect and round stars in the corners.
 
Also I find it strange that the ideal distance I found is 100.6mm when it is supposed to be 103.8 + 1mm for the spacer of my filters.
 
Am I missing something?
 
Sorry to ask questions more than I answer Sebastien
 
To the pleasure,
Malik


Fredd Drevon
 

Can you share a link to your frame. It is quite difficult to see the shape of stars. I have also tested this combination with movements of 0.2mm. I don't think you can get round stars in the corner but triangle shape seems odd.


On 3 May 2021, at 21:48, Malik AMZIANE <malik.amziane@...> wrote:


Hello all,
 
I was just going to open a discussion on this subject to seek the advice of Master Roland.
I received this week the focuser 3.5 to upgrade my AP130GT, in order to mount the QuadTCC on it.
I did 2 nights of testing with an ASI6200 and I can't manage to get perfectly picky stars in the corners.
 
I did about ten assemblies with different distances to 0.3mm and here is the best result I get.
 
I don't know if this is normal, if I have reached the maximum of what the Ap130/Quad combo can give. Or if I can still improve?
I had to adjust a slight tilt, and when I add or remove 0.5mm the field curvature increases.
For the settings I use CCDInspectore and ASTAP.
 
Maybe I am too demanding? The stars in the corners are not perfectly round but rather triangular.
 
I specify that before that I had mounted the QuadTCC on an LZOS 152F8, I managed to set the backfocus perfectly and I get perfect and round stars in the corners.
 
Also I find it strange that the ideal distance I found is 100.6mm when it is supposed to be 103.8 + 1mm for the spacer of my filters.
 
Am I missing something?
 
Sorry to ask questions more than I answer Sebastien
 
To the pleasure,
Malik

<3- BEST FOCUS CURV 17.4.jpg>
<ccdi.png>
<ASTAP.png>


Roland Christen
 

Do you have a closeup picture of your corner stars?

Rolando

-----Original Message-----
From: Malik AMZIANE <malik.amziane@...>
To: main@ap-ug.groups.io
Sent: Mon, May 3, 2021 3:48 pm
Subject: Re: [ap-ug] Info about 130GTX + 0.72x QuadTCC + ASI6200

Hello all,
 
I was just going to open a discussion on this subject to seek the advice of Master Roland.
I received this week the focuser 3.5 to upgrade my AP130GT, in order to mount the QuadTCC on it.
I did 2 nights of testing with an ASI6200 and I can't manage to get perfectly picky stars in the corners.
 
I did about ten assemblies with different distances to 0.3mm and here is the best result I get.
 
I don't know if this is normal, if I have reached the maximum of what the Ap130/Quad combo can give. Or if I can still improve?
I had to adjust a slight tilt, and when I add or remove 0.5mm the field curvature increases.
For the settings I use CCDInspectore and ASTAP.
 
Maybe I am too demanding? The stars in the corners are not perfectly round but rather triangular.
 
I specify that before that I had mounted the QuadTCC on an LZOS 152F8, I managed to set the backfocus perfectly and I get perfect and round stars in the corners.
 
Also I find it strange that the ideal distance I found is 100.6mm when it is supposed to be 103.8 + 1mm for the spacer of my filters.
 
Am I missing something?
 
Sorry to ask questions more than I answer Sebastien
 
To the pleasure,
Malik


Roland Christen
 


Also I find it strange that the ideal distance I found is 100.6mm
Yes, 100.6mm is correct for the GT lens. If you focus for best focus in the corners, the stars overall should be sharp and round.

Rolando


-----Original Message-----
From: Malik AMZIANE <malik.amziane@...>
To: main@ap-ug.groups.io
Sent: Mon, May 3, 2021 3:48 pm
Subject: Re: [ap-ug] Info about 130GTX + 0.72x QuadTCC + ASI6200

Hello all,
 
I was just going to open a discussion on this subject to seek the advice of Master Roland.
I received this week the focuser 3.5 to upgrade my AP130GT, in order to mount the QuadTCC on it.
I did 2 nights of testing with an ASI6200 and I can't manage to get perfectly picky stars in the corners.
 
I did about ten assemblies with different distances to 0.3mm and here is the best result I get.
 
I don't know if this is normal, if I have reached the maximum of what the Ap130/Quad combo can give. Or if I can still improve?
I had to adjust a slight tilt, and when I add or remove 0.5mm the field curvature increases.
For the settings I use CCDInspectore and ASTAP.
 
Maybe I am too demanding? The stars in the corners are not perfectly round but rather triangular.
 
I specify that before that I had mounted the QuadTCC on an LZOS 152F8, I managed to set the backfocus perfectly and I get perfect and round stars in the corners.
 
Also I find it strange that the ideal distance I found is 100.6mm when it is supposed to be 103.8 + 1mm for the spacer of my filters.
 
Am I missing something?
 
Sorry to ask questions more than I answer Sebastien
 
To the pleasure,
Malik


Roland Christen
 


triangle shape seems odd.
It will be triangle if it is slightly out of focus in the corners.

Rolando


-----Original Message-----
From: Fredd Drevon <frdrevon@...>
To: main@ap-ug.groups.io
Sent: Mon, May 3, 2021 6:28 pm
Subject: Re: [ap-ug] Info about 130GTX + 0.72x QuadTCC + ASI6200

Can you share a link to your frame. It is quite difficult to see the shape of stars. I have also tested this combination with movements of 0.2mm. I don't think you can get round stars in the corner but triangle shape seems odd.


On 3 May 2021, at 21:48, Malik AMZIANE <malik.amziane@...> wrote:


Hello all,
 
I was just going to open a discussion on this subject to seek the advice of Master Roland.
I received this week the focuser 3.5 to upgrade my AP130GT, in order to mount the QuadTCC on it.
I did 2 nights of testing with an ASI6200 and I can't manage to get perfectly picky stars in the corners.
 
I did about ten assemblies with different distances to 0.3mm and here is the best result I get.
 
I don't know if this is normal, if I have reached the maximum of what the Ap130/Quad combo can give. Or if I can still improve?
I had to adjust a slight tilt, and when I add or remove 0.5mm the field curvature increases.
For the settings I use CCDInspectore and ASTAP.
 
Maybe I am too demanding? The stars in the corners are not perfectly round but rather triangular.
 
I specify that before that I had mounted the QuadTCC on an LZOS 152F8, I managed to set the backfocus perfectly and I get perfect and round stars in the corners.
 
Also I find it strange that the ideal distance I found is 100.6mm when it is supposed to be 103.8 + 1mm for the spacer of my filters.
 
Am I missing something?
 
Sorry to ask questions more than I answer Sebastien
 
To the pleasure,
Malik

<3- BEST FOCUS CURV 17.4.jpg>
<ccdi.png>
<ASTAP.png>


Malik AMZIANE
 

         ---  Yes, 100.6mm is correct for the GT lens. If you focus for best focus in the corners, the stars overall should be sharp and round.-----

I thought the GT and GTX lenses were identical apart from the oil bath, interesting to learn!
 
Does this imply that with a GTX the result in the corners will be better? Or easier to obtain?
 
In this image, I just manually adjusted the focus and this is the best result I got, as you can see on the astap analysis, the center is higher than the corners. When I do autofocus, it's the opposite (2.60 in the center and more than 3.00 in the corners) but in this case the corners are even worse.

        ------  
I have also tested this combination with movements of 0.2mm. -------

Fred I would be curious to see your result, it will be interesting to compare.
 
I enclose a wetransfer link with the complete image.
And here is a close-up on the 4 corners,

https://we.tl/t-VN3f0viM55



Malik


Khushrow Machhi
 

I have the 130GTX+QTCC+ASI6200MM.  I tried very hard to get perfectly round stars at each of the four corners and after many nights of experimenting gave up after I got what I feel is close enough.  I ended up with an optimal distance in my setup at 103.1mm.  I also had 0.3mm M68 spacer rings that I used.  I believe that the small pixel size of the ASI6200 and the large image area exposes any flaws in the imaging train. I believe there is a slight tilt in my system which I tried to correct with an M68 tilt adapter but this was a futile effort.  With the current setup I get round stars in three corners but the fourth corner I do get triangles for stars at the edge and it is more noticeable if a larger star happens to be in this corner.  With the field flattener stars are round across the image with the same spacing.  I do love my 130GTX setup and the images are a joy.
Khushrow 


sebkersten
 

I Khusurow

Thank you for sharing this experience.

I just saw your images on Astrobin, wow!
I understand better what you say about the corner of the image.

Perhaps you can send me 1 fit picture (unique exposure of 180 sec foe exemple, in L channel.

I could really compare the shape of the stars on the whole image, and confirm that it is this level of result that I am looking for.

Sincerely,

Sébastien

Le 4 mai 2021 à 05:17, Khushrow Machhi via groups.io <kmachhi@...> a écrit :

I have the 130GTX+QTCC+ASI6200MM.  I tried very hard to get perfectly round stars at each of the four corners and after many nights of experimenting gave up after I got what I feel is close enough.  I ended up with an optimal distance in my setup at 103.1mm.  I also had 0.3mm M68 spacer rings that I used.  I believe that the small pixel size of the ASI6200 and the large image area exposes any flaws in the imaging train. I believe there is a slight tilt in my system which I tried to correct with an M68 tilt adapter but this was a futile effort.  With the current setup I get round stars in three corners but the fourth corner I do get triangles for stars at the edge and it is more noticeable if a larger star happens to be in this corner.  With the field flattener stars are round across the image with the same spacing.  I do love my 130GTX setup and the images are a joy.
Khushrow 


Chris White
 

On Mon, May 3, 2021 at 11:17 PM, Khushrow Machhi wrote:
I have the 130GTX+QTCC+ASI6200MM.  I tried very hard to get perfectly round stars at each of the four corners and after many nights of experimenting gave up after I got what I feel is close enough.  I ended up with an optimal distance in my setup at 103.1mm.  I also had 0.3mm M68 spacer rings that I used.  I believe that the small pixel size of the ASI6200 and the large image area exposes any flaws in the imaging train. I believe there is a slight tilt in my system which I tried to correct with an M68 tilt adapter but this was a futile effort.  With the current setup I get round stars in three corners but the fourth corner I do get triangles for stars at the edge and it is more noticeable if a larger star happens to be in this corner.  With the field flattener stars are round across the image with the same spacing.  I do love my 130GTX setup and the images are a joy.
Khushrow 

My experience matches Khushrow's.  I did a lot of spacing testing with the GTX+QTCC and could not quite get perfect stars in all corners but settled in at "good enough."  Using Roland's method of finding focus and then checking corners after a few steps in and then out, revealed the sweet spot at 105.7mm.   It's odd that my spacing is quite a bit different than Khushrow's.  Spec is 102.9mm, but with a filter in the path that would be 103.9mm.  So I'm at 1.8mm over spec.  I also had a very small amount of tilt to contend with that I "mostly" corrected with a Gerd CTU. 

FWIW- Roland stated to me (through George) that you won't get perfect stars in the corners with this setup and 3.76um pixels. 

In all honesty, I do think this is good enough.  This is a MASSIVE field and with tiny pixels is still a very high resolution image.  Regardless of what camera you decide to use I'd jump on that GTX if you have the option to buy!  It's an amazing scope. 


sebkersten
 

Hi Chris

Thanks to share this explain.  The feedbacks are always very interesting

By the way, the attached picture is interesting.  Is it made in the L channel with a similar camera?
I wish I had stars like that.

Thanks for the feedback from Roland.  I guess with the flattener, everything is easier.

One more thing, could you show me a flat?

Sincerely

Sébastien

Le 4 mai 2021 à 13:09, Chris White <chris.white@...> a écrit :

On Mon, May 3, 2021 at 11:17 PM, Khushrow Machhi wrote:
I have the 130GTX+QTCC+ASI6200MM.  I tried very hard to get perfectly round stars at each of the four corners and after many nights of experimenting gave up after I got what I feel is close enough.  I ended up with an optimal distance in my setup at 103.1mm.  I also had 0.3mm M68 spacer rings that I used.  I believe that the small pixel size of the ASI6200 and the large image area exposes any flaws in the imaging train. I believe there is a slight tilt in my system which I tried to correct with an M68 tilt adapter but this was a futile effort.  With the current setup I get round stars in three corners but the fourth corner I do get triangles for stars at the edge and it is more noticeable if a larger star happens to be in this corner.  With the field flattener stars are round across the image with the same spacing.  I do love my 130GTX setup and the images are a joy.
Khushrow 

My experience matches Khushrow's.  I did a lot of spacing testing with the GTX+QTCC and could not quite get perfect stars in all corners but settled in at "good enough."  Using Roland's method of finding focus and then checking corners after a few steps in and then out, revealed the sweet spot at 105.7mm.   It's odd that my spacing is quite a bit different than Khushrow's.  Spec is 102.9mm, but with a filter in the path that would be 103.9mm.  So I'm at 1.8mm over spec.  I also had a very small amount of tilt to contend with that I "mostly" corrected with a Gerd CTU. 

FWIW- Roland stated to me (through George) that you won't get perfect stars in the corners with this setup and 3.76um pixels. 

In all honesty, I do think this is good enough.  This is a MASSIVE field and with tiny pixels is still a very high resolution image.  Regardless of what camera you decide to use I'd jump on that GTX if you have the option to buy!  It's an amazing scope. 

<130GTX-QTCC-6200.jpg>


sebkersten
 

Hi Khushrow

I just release the mail from Chris, and I see I spelled your name wrong.  Sorry for the mistake.

Sincerely

Sébastien

Le 4 mai 2021 à 05:17, Khushrow Machhi via groups.io <kmachhi@...> a écrit :

I have the 130GTX+QTCC+ASI6200MM.  I tried very hard to get perfectly round stars at each of the four corners and after many nights of experimenting gave up after I got what I feel is close enough.  I ended up with an optimal distance in my setup at 103.1mm.  I also had 0.3mm M68 spacer rings that I used.  I believe that the small pixel size of the ASI6200 and the large image area exposes any flaws in the imaging train. I believe there is a slight tilt in my system which I tried to correct with an M68 tilt adapter but this was a futile effort.  With the current setup I get round stars in three corners but the fourth corner I do get triangles for stars at the edge and it is more noticeable if a larger star happens to be in this corner.  With the field flattener stars are round across the image with the same spacing.  I do love my 130GTX setup and the images are a joy.
Khushrow 


Chris White
 
Edited

On Tue, May 4, 2021 at 12:01 PM, sebkersten wrote:
Hi Chris
 
Thanks to share this explain.  The feedbacks are always very interesting
 
By the way, the attached picture is interesting.  Is it made in the L channel with a similar camera?
I wish I had stars like that.
 
Thanks for the feedback from Roland.  I guess with the flattener, everything is easier.
 
One more thing, could you show me a flat?
 
Sincerely
 
Sébastien
Sebastien,

That was red frame taken with the ASI 6200. 

Here is a link to a flat frame and a luminance frame so you can evaluate. 
https://www.dropbox.com/sh/sbmbxvu6nc542s0/AAD_tDVBvOiqmUNv9T5QVmE7a?dl=0


sebkersten
 

Hi Chris

Thanks for the link, it’s really friendly.
I just download the fit’s, and look it in the current of the day.

Sincerely

Sébastien

Le 4 mai 2021 à 23:58, Chris White <chris.white@...> a écrit :

On Tue, May 4, 2021 at 12:01 PM, sebkersten wrote:
Hi Chris
 
Thanks to share this explain.  The feedbacks are always very interesting
 
By the way, the attached picture is interesting.  Is it made in the L channel with a similar camera?
I wish I had stars like that.
 
Thanks for the feedback from Roland.  I guess with the flattener, everything is easier.
 
One more thing, could you show me a flat?
 
Sincerely
 
Sébastien
Sebastien,

That was red.  

Here is a link to a flat frame and a luminance frame so you can evaluate.  
https://www.dropbox.com/sh/sbmbxvu6nc542s0/AAD_tDVBvOiqmUNv9T5QVmE7a?dl=0


Chris White
 

I might even be able to improve it a little more from here.  I was at the point where I was making 0.2mm adjustments in backspacing and decided that I was close enough for my needs.  After integrating many subs I think it will look even better.  I also might try to run drizzle and then downsample to see if that rounds out the stars, but that might make my computer choke with those huge files. 

It will need to wait for galaxy season to end, as right now I have the Flattener on and waiting for a clear night to image at the scopes native FL. 


Chris White
 

A question for Roland:

When I was doing all of my spacing evaluation for the 6200+GTX+QTCC I started at spec and increased my spacing until I saw no additional improvement.  This put me at 1.8mm over spec for spacing.  I see a couple of people posting in this thread who have decided that being under the spec with backspacing yielded better results. 

In your experience when trying to correct for such a large field with the QTCC+GTX, would you expect needing additional backspacing or less backspacing from spec? 

Thank you,


Fredd Drevon
 

Out of interest, with the flattener, do you get fully round stars.

On 5 May 2021, at 12:18, Chris White <chris.white@...> wrote:

I might even be able to improve it a little more from here.  I was at the point where I was making 0.2mm adjustments in backspacing and decided that I was close enough for my needs.  After integrating many subs I think it will look even better.  I also might try to run drizzle and then downsample to see if that rounds out the stars, but that might make my computer choke with those huge files. 

It will need to wait for galaxy season to end, as right now I have the Flattener on and waiting for a clear night to image at the scopes native FL. 


Chris White
 
Edited

On Wed, May 5, 2021 at 07:22 AM, Fredd Drevon wrote:
Out of interest, with the flattener, do you get fully round stars.
I'm not certain yet but I know of other users who have shown round stars with the FF and full frame sensor.  I just purchased this scope a couple of months ago and installed the flattener a few days ago.  Hoping to test soon if these april showers ever subside.