TCC quad .72 and 1mm soacers question


Peter Gottstein
 
Edited

I currently using a set up with TCC quad with imaging train consisting of TEC 140,night crawler focuser, QHY filter wheel, OAG, QHY 600 camera. I used precision  parts adapters to be sure that I the recommended spacing dialed in. My stars at the corners of my image all face the same inward direction. The stars take on a teardrop shape with skinny part facing inward. I currently have inserted 2 additional spacing rings (1mm) each to the quad. Is it common to use the full set which would be a total of additional 3 mm to achieve pinpoint stars? Seems like a lot. I initially used Rolands method to figure which direction to adjust spacers. My  calculation of .3mm off. So I added 1mm spacer, no success I than added  a second spacer. So total of 2mm of spacers, but  no success  yet. Any help be appreciated. 

BEST

PEETY G


Roland Christen
 

TEC made 3 different TEC 140 scopes. The first generation ED, then a second generation ED which has the outer elements switched, and finally the 140 FL. They are all somewhat different and may require a different spacing arrangement. I can run the numbers in the design program for each of the versions.

Rolando

-----Original Message-----
From: Peter Gottstein <peetyg1@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 22, 2022 8:14 am
Subject: [ap-gto] TCC quad .72 and 1mm soacers question

[Edited Message Follows]
I currently using a set up with TCC quad with imaging train consisting of TEC 140,night crawler focuser, QHY filter wheel, OAG, QHY 600 camera. I used precision  parts adapters to be sure that I the recommended spacing dialed in. My stars at the corners of my image all face the same inward direction. The stars take on a teardrop shape with skinny part facing inward. I currently have inserted 2 additional spacing rings (1mm) each to the quad. Is it common to use the full set which would be a total of additional 3 mm to achieve pinpoint stars? Seems like a lot. I initially used Rolands method to figure which direction to adjust spacers. My  calculation of .3mm off. So I added 1mm spacer, no success I than added  a second spacer. So total of 2mm of spacers, but  no success  yet. Any help be appreciated. 
BEST

PEETY G

--
Roland Christen
Astro-Physics


Peter Gottstein
 

I purchased new about 3 months ago. Your help would be appreciated. 


peety 


Roland Christen
 

So is it a 140FL? The fluorite version?

Roland

-----Original Message-----
From: Peter Gottstein <peetyg1@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 22, 2022 6:38 pm
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

I purchased new about 3 months ago. Your help would be appreciated. 

peety 

--
Roland Christen
Astro-Physics


Peter Gottstein
 

Yes


Roland Christen
 

For the 140FL lens the back distance is between 98.0 to 98.5mm, measured from the back flange of the TCC. If you use the 18.3mm extension then the distance from the back flange of that piece is 79.7 to 80.2mm.
Add 1 mm for a 3mm filter thickness if you use filters. 

Roland Christen

-----Original Message-----
From: Peter Gottstein <peetyg1@...>
To: main@ap-gto.groups.io
Sent: Fri, Jul 22, 2022 8:19 pm
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

Yes

--
Roland Christen
Astro-Physics


Andrew J
 

On Sat, Jul 23, 2022 at 08:49 AM, Roland Christen wrote:
For the 140FL lens the back distance is between 98.0 to 98.5mm, measured from the back flange of the TCC. If you use the 18.3mm extension then the distance from the back flange of that piece is 79.7 to 80.2mm.
Add 1 mm for a 3mm filter thickness if you use filters. 
Hi Roland.

I have the 140ED version (the one just before the FL version came out). I use it with the QUADTCC with the 18.3mm extension. The backspacing I have been using is 80.8mm. Is this correct for this version of the TEC 140?

Thanks.
Andrew J


Roland Christen
 

This distance should work for the 140ED. What results are you getting?

Roland

-----Original Message-----
From: Andrew J <andjones132@...>
To: main@ap-gto.groups.io
Sent: Mon, Jul 25, 2022 10:29 am
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

On Sat, Jul 23, 2022 at 08:49 AM, Roland Christen wrote:
For the 140FL lens the back distance is between 98.0 to 98.5mm, measured from the back flange of the TCC. If you use the 18.3mm extension then the distance from the back flange of that piece is 79.7 to 80.2mm.
Add 1 mm for a 3mm filter thickness if you use filters. 
Hi Roland.

I have the 140ED version (the one just before the FL version came out). I use it with the QUADTCC with the 18.3mm extension. The backspacing I have been using is 80.8mm. Is this correct for this version of the TEC 140?

Thanks.
Andrew J

--
Roland Christen
Astro-Physics


Luca Marinelli
 

Roland,

Can you please comment on what parameters you use for optimization of the backfocus distance from the flattener or TCC? Is it nulling curvature over a specified field or is it a trade-off between multiple aberrations in the corrected field? 

Thanks!

Luca

On Jul 25, 2022, at 9:02 AM, Roland Christen via groups.io <chris1011@...> wrote:


This distance should work for the 140ED. What results are you getting?

Roland

-----Original Message-----
From: Andrew J <andjones132@...>
To: main@ap-gto.groups.io
Sent: Mon, Jul 25, 2022 10:29 am
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

On Sat, Jul 23, 2022 at 08:49 AM, Roland Christen wrote:
For the 140FL lens the back distance is between 98.0 to 98.5mm, measured from the back flange of the TCC. If you use the 18.3mm extension then the distance from the back flange of that piece is 79.7 to 80.2mm.
Add 1 mm for a 3mm filter thickness if you use filters. 
Hi Roland.

I have the 140ED version (the one just before the FL version came out). I use it with the QUADTCC with the 18.3mm extension. The backspacing I have been using is 80.8mm. Is this correct for this version of the TEC 140?

Thanks.
Andrew J

--
Roland Christen
Astro-Physics


Roland Christen
 

Minimum spot size off-axis.

Rolando

-----Original Message-----
From: Luca Marinelli <photo@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Mon, Jul 25, 2022 11:11 am
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

Roland,

Can you please comment on what parameters you use for optimization of the backfocus distance from the flattener or TCC? Is it nulling curvature over a specified field or is it a trade-off between multiple aberrations in the corrected field? 

Thanks!

Luca

On Jul 25, 2022, at 9:02 AM, Roland Christen via groups.io <chris1011@...> wrote:


This distance should work for the 140ED. What results are you getting?

Roland

-----Original Message-----
From: Andrew J <andjones132@...>
To: main@ap-gto.groups.io
Sent: Mon, Jul 25, 2022 10:29 am
Subject: Re: [ap-gto] TCC quad .72 and 1mm soacers question

On Sat, Jul 23, 2022 at 08:49 AM, Roland Christen wrote:
For the 140FL lens the back distance is between 98.0 to 98.5mm, measured from the back flange of the TCC. If you use the 18.3mm extension then the distance from the back flange of that piece is 79.7 to 80.2mm.
Add 1 mm for a 3mm filter thickness if you use filters. 
Hi Roland.

I have the 140ED version (the one just before the FL version came out). I use it with the QUADTCC with the 18.3mm extension. The backspacing I have been using is 80.8mm. Is this correct for this version of the TEC 140?

Thanks.
Andrew J

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Andrew J
 

On Mon, Jul 25, 2022 at 09:02 AM, Roland Christen wrote:
What results are you getting?
Hi Roland.

Results are OK. I was just curious if there was a more accurate backfocus range for the TEC 140ED Gen 2. I think I got the 80.8mm bf from the AP website, so I assume it is correct.

Andrew


Peter Gottstein
 

Roland I appreciate you running numbers. When I try to dial between 99.0 - 99.5 (have filters) using spacers into that range the corners look terrible.  I even ran the pictures thru CCD, PIxinsight, APTX,  ect. What’s even crazier is when go way beyond to total backfocus of 102mm that’s when corners seem ok. How can this be that far off. I spoke to George who also confirmed that stars need the corrector to be moved further away and it was not a tilt. I am wondering if I should just go flatner as quad just seems way off. Again I am using 140FL, qhy 600 camera. 


best 

Peter