Date   

Re: Aperture vs Focal Ratio to determine exposure time

Joe Renzetti <axnyslie@...>
 

I have done the same objects with the same camera and aperture at f/2, f/6.3, and f/10. It makes a very significant difference. It is not a "myth"

Joe

On Sat, May 12, 2018 at 5:21 PM, pnagy@... [ap-gto] <ap-gto@...> wrote:
 

Now you can sell your TOA 130 and get Absolute Encoder Kit.

Peter



---In ap-gto@..., wrote :

When I posted the data on this thread (I am the OP) I was just trying to show the difference between a 130mm aperture refractor at 1000mm focal length, and a 254mm aperture Newt at 1000mm focal length, on the same target with the same camera (and of course my trusty AP1100 mount, but that isnt relevant). I had no idea it would spark so much discussion about the topic, although a lot of it has been very interesting to see unfold. The idea was to show newer folks what happens when you simply change the aperture and hold all of the other values constant.






From: ap-gto@... <ap-gto@...> on behalf of pnagy@... [ap-gto] <ap-gto@...>
Sent: Saturday, May 12, 2018 1:17 PM
To: ap-gto@...
Subject: [ap-gto] Re: Aperture vs Focal Ratio to determine exposure time
 
 

Are you using same camera at F/10 and F/2? If you are using same camera, I find it hard to believe you get similar performance at similar exposure times at f/10 and f/2. If you are using different cameras with different pixel sizes which changes image scale, then I can believe it.

I find Stan Moore's article very misleading and poorly written.

Peter



---In ap-gto@..., wrote :

Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.



Re: Aperture vs Focal Ratio to determine exposure time

topboxman
 

Now you can sell your TOA 130 and get Absolute Encoder Kit.

Peter


---In ap-gto@..., <bill@...> wrote :

When I posted the data on this thread (I am the OP) I was just trying to show the difference between a 130mm aperture refractor at 1000mm focal length, and a 254mm aperture Newt at 1000mm focal length, on the same target with the same camera (and of course my trusty AP1100 mount, but that isnt relevant). I had no idea it would spark so much discussion about the topic, although a lot of it has been very interesting to see unfold. The idea was to show newer folks what happens when you simply change the aperture and hold all of the other values constant.






From: ap-gto@... <ap-gto@...> on behalf of pnagy@... [ap-gto] <ap-gto@...>
Sent: Saturday, May 12, 2018 1:17 PM
To: ap-gto@...
Subject: [ap-gto] Re: Aperture vs Focal Ratio to determine exposure time
 
 

Are you using same camera at F/10 and F/2? If you are using same camera, I find it hard to believe you get similar performance at similar exposure times at f/10 and f/2. If you are using different cameras with different pixel sizes which changes image scale, then I can believe it.

I find Stan Moore's article very misleading and poorly written.

Peter



---In ap-gto@..., <mkea13800@...> wrote :

Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.


Re: Odd APCC LOG entries

Ray Gralak
 

Joe,

If your CP4 was not working correctly then all bets are off on the accuracy of values in the log.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, May 12, 2018 1:53 PM
To: ap-gto@...
Subject: [ap-gto] Odd APCC LOG entries



Hi Ray,

I’ve been trying to read through the few minutes of the log file, when my second CP4 went berserk, besides
several other weird entries,
I keep seeing DOUBLE entries from 3DVIEW, for changes in DEC.
For example:

0012563 2018-04-21 22:23:34.096: Debug, 3DView, Dec Angle Changed = 41.5518291419454

0012564 2018-04-21 22:23:34.096: Debug, 3DView, RA Angle Changed = 180

0012565 2018-04-21 22:23:34.096: Debug, 3DView, Dec Angle Changed = 88.4602777777778

That RA mount speed is pretty darned fast, to do a 180 degree-Turtle, in zero time.

How can the DECLINATION be in TWO places at the exact same time – Time Travel, DiLithium Crystal –
sheeesh?
No wonder this second unit ... also had a stroke, and suddenly ... it was Deceased !!!

I have even seen the first DEC report a positive angle , and the very next line, repeated at the same clock time,
of a huge DEC negative angle. A few times BOTH DEC readouts have EVEN been identical, but that is pretty
rare.

Here is just one example of this dichotomy – the CP4 must be super colossal, to flip that fast in less than a
millisecond.

0000295 2018-04-21 22:18:51.282: Debug, 3DView, Dec Angle Changed = 46.3716666666667

0000296 2018-04-21 22:18:51.282: Debug, 3DView, Dec Angle Changed = -226.371666666667

How do I interpret such strange messages – it isn’t even a complimentary angle?
Is one of these a “servo gear angle” ?

I think we need a Manual, rather than just an Appendix section in the user guide, to understand the APCC log.

Joe


Re: Aperture vs Focal Ratio to determine exposure time

Bill Long
 

When I posted the data on this thread (I am the OP) I was just trying to show the difference between a 130mm aperture refractor at 1000mm focal length, and a 254mm aperture Newt at 1000mm focal length, on the same target with the same camera (and of course my trusty AP1100 mount, but that isnt relevant). I had no idea it would spark so much discussion about the topic, although a lot of it has been very interesting to see unfold. The idea was to show newer folks what happens when you simply change the aperture and hold all of the other values constant.






From: ap-gto@... on behalf of pnagy@... [ap-gto]
Sent: Saturday, May 12, 2018 1:17 PM
To: ap-gto@...
Subject: [ap-gto] Re: Aperture vs Focal Ratio to determine exposure time
 
 

Are you using same camera at F/10 and F/2? If you are using same camera, I find it hard to believe you get similar performance at similar exposure times at f/10 and f/2. If you are using different cameras with different pixel sizes which changes image scale, then I can believe it.

I find Stan Moore's article very misleading and poorly written.

Peter



---In ap-gto@..., wrote :

Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.


Odd APCC LOG entries

Joe Zeglinski
 

Hi Ray,
 
    I’ve been trying to read through the few minutes of the log file, when my second CP4 went berserk,  besides several other weird entries,
I keep seeing DOUBLE entries from 3DVIEW,  for changes in DEC.
For example:
0012563 2018-04-21 22:23:34.096: Debug, 3DView, Dec Angle Changed = 41.5518291419454

0012564 2018-04-21 22:23:34.096: Debug, 3DView, RA Angle Changed = 180

0012565 2018-04-21 22:23:34.096: Debug, 3DView, Dec Angle Changed = 88.4602777777778

That RA mount speed is pretty darned fast, to do a 180 degree-Turtle,  in zero time.

    How can the DECLINATION  be in TWO places at the exact same time – Time Travel, DiLithium Crystal – sheeesh?
No wonder this second unit ... also had a stroke, and suddenly ... it was Deceased !!!

    I have even seen the first DEC report a positive angle , and the very next line,  repeated at the same clock time, of a huge DEC negative angle. A few times BOTH DEC readouts  have EVEN been identical, but that is pretty rare.

Here is just one example of this dichotomy – the CP4 must be super colossal,  to flip that fast in less than a millisecond.

0000295 2018-04-21 22:18:51.282: Debug, 3DView, Dec Angle Changed = 46.3716666666667

0000296 2018-04-21 22:18:51.282: Debug, 3DView, Dec Angle Changed = -226.371666666667

How do I interpret such strange messages – it isn’t even a complimentary angle?
Is one of these a “servo gear angle” ?

    I think we need a Manual, rather than just an Appendix section in the user guide, to understand the APCC log.

Joe


Re: Aperture vs Focal Ratio to determine exposure time

topboxman
 

Are you using same camera at F/10 and F/2? If you are using same camera, I find it hard to believe you get similar performance at similar exposure times at f/10 and f/2. If you are using different cameras with different pixel sizes which changes image scale, then I can believe it.

I find Stan Moore's article very misleading and poorly written.

Peter


---In ap-gto@..., <mkea13800@...> wrote :

Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.


Re: Sanity Check on my PEC

Jerome Yesavage
 

Thanks very much.  I can see that. Can you edit off the wayward data before computing the curve? 

Also, since I need to redo mine, I believe there was a criteria for which harmonics to include in the model?

Finally, as a test, if you get the model and upload it to the mount, and collect new data with the model on, the RMS should be smaller than the original, right?

You can tell this is a sanity check.....


Re: Aperture vs Focal Ratio to determine exposure time

Roland Christen
 

I'm with Stan Moore up to a point. Aperture certainly makes a difference, more than F-ratio, but other things also affect your final image: resolution of small objects, whether or not you are undersampled, what field of view you wish to capture, etc.

Rolando



-----Original Message-----
From: Donald Rudny mkea13800@... [ap-gto]
To: ap-gto <ap-gto@...>
Sent: Sat, May 12, 2018 1:58 pm
Subject: [ap-gto] Re: Aperture vs Focal Ratio to determine exposure time



Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.




Re: PHD2 aggressiveness with Absolute Encoders

Roland Christen
 

Then set Min Move higher per what you expect to see during the imaging session and set aggressiveness lower.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto]
To: ap-gto
Sent: Sat, May 12, 2018 1:40 pm
Subject: Re: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I agree with you but seeing always changes during imaging session and in my case the seeing usually gets worse. I usually go to sleep while the automation software (SGPro) does the dirty work for me so I cannot monitor seeing and change Min Move as well as Aggressiveness.

Peter


---In ap-gto@..., wrote :


My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move.
Min Move is a variable. It should be set for the seeing of each session, which is not always the same . It should not be some fixed random number. Take a few minutes before each session and characterize the seeing by doing a short unguided run in Dec and measuring the maximum fluctuation of the guide star via the guider graph. Then set the Min Move at that level.

Rolando


-----Original Message-----
From: pnagy@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, May 12, 2018 11:57 am
Subject: Re: [ap-gto] PHD2 aggressiveness with Absolute Encoders



Hi Rolando,

Thanks for the prompt response. My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move. I think larger Min Move will improve. Good point about low aggressiveness and dithering. I will try guiding with 80% aggressiveness on the next clear night.

Peter


---In ap-gto@..., wrote :

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter








Re: Sanity Check on my PEC

Roland Christen
 


Was told here that I only need 3 cycles.  Is this still the standard, or should I get more?
3 cycles is what I would use, but others say perhaps 5 or more cycles might give a tad more accuracy. It all depends on what the drift is over a number of cycles. PEMPro has an option to cancel the drift as it acquires the curve, so you can watch as the subsequent worm cycles are being recorded. As long as they lie on top of each other within a few arc seconds, you can continue to gather data. As soon as you get one of the curves to start wandering off, then this compromises the data and you won't get a PE curve that fully compensates for the mount's periodic error.

Rolando



-----Original Message-----
From: yesavage@... [ap-gto]
To: ap-gto
Sent: Sat, May 12, 2018 1:15 pm
Subject: [ap-gto] Sanity Check on my PEC



Hi, had my Mach1 worked on and it is now correcting well but the original curve had a peak to peak of 3.4 ArcSec.  With my PEC cranked it it is 3.8!  I just checked.

Time for a new curve, I guess. 

Was told here that I only need 3 cycles.  Is this still the standard, or should I get more?

Thanks,

JY

PS  What can I expect to get it down to from 3.4? 




Re: Aperture vs Focal Ratio to determine exposure time

Donald Rudny
 

Peter,

I’ve been researching this recently and found this article by Craig Stark that I also posted in the EAA section of CN.  I was interested because I found that using my C11 at f/10 versus f/2 with Hyperstar doesn’t require much more exposure for the same object and certainly not 25 times more.  Stan Moore also has an article referred to in Craig’s article that states f ratio doesn’t matter for digital cameras as long as the signal stays well above the read noise.  It’s aperture that makes the difference.  It’s different for film.  Great topic.  I’ll be interesting to see what others think.


Aperture vs Focal Ratio to determine exposure time

topboxman
 

Please see the following Cloudy Nights thread about aperture vs focal ratio:

https://www.cloudynights.com/topic/617363-speed-of-optics-example/

Personally I believe focal ratio helps determine imaging speed and aperture determines SNR. I know it gets complicated when optics mix with camera like image scale.

Let me know what you think?

Peter


Re: PHD2 aggressiveness with Absolute Encoders

topboxman
 

I agree with you but seeing always changes during imaging session and in my case the seeing usually gets worse. I usually go to sleep while the automation software (SGPro) does the dirty work for me so I cannot monitor seeing and change Min Move as well as Aggressiveness.

Peter


---In ap-gto@..., <chris1011@...> wrote :


My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move.
Min Move is a variable. It should be set for the seeing of each session, which is not always the same. It should not be some fixed random number. Take a few minutes before each session and characterize the seeing by doing a short unguided run in Dec and measuring the maximum fluctuation of the guide star via the guider graph. Then set the Min Move at that level.

Rolando


-----Original Message-----
From: pnagy@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, May 12, 2018 11:57 am
Subject: Re: [ap-gto] PHD2 aggressiveness with Absolute Encoders



Hi Rolando,

Thanks for the prompt response. My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move. I think larger Min Move will improve. Good point about low aggressiveness and dithering. I will try guiding with 80% aggressiveness on the next clear night.

Peter


---In ap-gto@..., <chris1011@...> wrote :

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter






Sanity Check on my PEC

Jerome Yesavage
 

Hi, had my Mach1 worked on and it is now correcting well but the original curve had a peak to peak of 3.4 ArcSec.  With my PEC cranked it it is 3.8!  I just checked.

Time for a new curve, I guess. 

Was told here that I only need 3 cycles.  Is this still the standard, or should I get more?

Thanks,

JY

PS  What can I expect to get it down to from 3.4? 



Re: PHD2 aggressiveness with Absolute Encoders

Roland Christen
 


My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move.
Min Move is a variable. It should be set for the seeing of each session, which is not always the same. It should not be some fixed random number. Take a few minutes before each session and characterize the seeing by doing a short unguided run in Dec and measuring the maximum fluctuation of the guide star via the guider graph. Then set the Min Move at that level.

Rolando


-----Original Message-----
From: pnagy@... [ap-gto]
To: ap-gto
Sent: Sat, May 12, 2018 11:57 am
Subject: Re: [ap-gto] PHD2 aggressiveness with Absolute Encoders



Hi Rolando,

Thanks for the prompt response. My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move. I think larger Min Move will improve. Good point about low aggressiveness and dithering. I will try guiding with 80% aggressiveness on the next clear night.

Peter


---In ap-gto@..., wrote :

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter






Re: PHD2 aggressiveness with Absolute Encoders

topboxman
 

Hi Rolando,

Thanks for the prompt response. My Min Move was set a little too low because I noticed quite a few corrections sent to the mount. I increased Min Move but I have not yet tested with the new Min Move. I think larger Min Move will improve. Good point about low aggressiveness and dithering. I will try guiding with 80% aggressiveness on the next clear night.

Peter


---In ap-gto@..., <chris1011@...> wrote :

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter




Re: PHD2 aggressiveness with Absolute Encoders

Roland Christen
 

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.

Rolando



-----Original Message-----
From: pnagy@... [ap-gto]
To: ap-gto
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders



I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter




PHD2 aggressiveness with Absolute Encoders

topboxman
 

I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

https://peternagy.smugmug.com/Telescopes/Current-Equipment/

Thank you,
Peter



Re: Pointing Model

Ray Gralak
 

A pointing model, e.g. APPM or Astrotortilla, will make your slews accurate, but not your guiding.
APCC Pro also provides tracking rate correction in addition to pointing correction. Provided there is a good model in place with repeatable pointing, mount RA and Dec tracking are adjusted dynamically by APCC to remove drift, which may result in improved autoguiding performance.

The reason I want to build this model is that the mount in guiding beautifully but once i have PHD and SGP
working the auto guiding is very erratic with some large cor rections up to 1.5 arc/sec.
There are several reasons why this might happen, but the most common is that aggressiveness might be set too high. PHD2 tends to overestimate Dec backlash so if aggressiveness is set too high in PHD2 that can result in unstable dec guiding.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, May 11, 2018 10:26 AM
To: ap-gto@...
Subject: [ap-gto] Re: Pointing Model



Vince

Are you perhaps confusing guiding with pointing accuracy? Pointing is the ability for the mount to slew to a
specific object.

A pointing model, e.g. APPM or Astrotortilla, will make your slews accurate, but not your guiding.

Are you using PHD or PHD2? There is a substantial difference.

Bryan


---In ap-gto@..., <salfranc@...> wrote :



Hi,

I read somewhere that to increase the guiding accuracy I need to build a pointing model. I have read the manual
but failed to find a way to build this model. Can you please point me in the right direction. Thank you.

The reason I want to build this model is that the mount in guiding beautifully but once i have PHD and SGP
working the auto guiding is very erratic with some large cor rections up to 1.5 arc/sec.

I have created a PEC curve with Pempro and this did improve the auto guiding.

Thanks

Vince



Re: Pointing Model

Worsel
 

Vince

Are you perhaps confusing guiding with pointing accuracy?  Pointing is the ability for the mount to slew to a specific object.  

A pointing model, e.g. APPM or Astrotortilla, will make your slews accurate, but not your guiding.

Are you using PHD or PHD2?  There is a substantial difference.

Bryan


---In ap-gto@..., <salfranc@...> wrote :

Hi,

I read somewhere that to increase the guiding accuracy I need to build a pointing model. I have read the manual but failed to find a way to build this model. Can you please point me in the right direction. Thank you.

The reason I want to build this model is that the mount in guiding beautifully but once i have PHD and SGP working the auto guiding is very erratic with some large corrections up to 1.5 arc/sec. 

I have created a PEC curve with Pempro and this did improve the auto guiding.

Thanks

Vince