Exos 2 PMC8 telescope size #EXOS2


kevin power
 

Hi all i have had my mount just under a year now with no real issues. 

Generally use ED80 with ZWO 290mc camera and guide scope and can easily get 300 seconds and 600 second images after a decent polar alignment.

I now have a 200pds, 8 inch newtonion and can not use on this mount? Phd2 can not control the mount at all my total guiding is about 50 but goes higher.

I use the same 50mm guide scope could this be too small or is the mount just not capable of a telescope this size?

Is there anything I can try setting wise?

Thanks for any help


jrichard333 <jrichard333@hotmail.com>
 

Howdy,

 

Just so you know up front, I mostly do planetary imaging.  I’ve dabbled a

little into DSOs.

 

I don’t think it’s the mount.  The EXOS-2GT PMC8 can hold a lot of weight.

I’ve seen it handle over 80Ibs (36kg).  I have an iEXOS-100 with the  ST3

tripod legs and it can easily handle 20Ibs (9.1kg) and the rating for this mount

is a lot less.   Just make sure you are balanced and you should be fine once

you develop new settings for PHD2.

 

You will have to start over using PHD2 (settings, etc.); why, you are going from:

1.        a small foot print (ED80) to a larger foot print (200dps) scope

2.        a shorter focal length (480mm) to a longer focal length (1000mm)

 

Higher focal lengths make alignment a bit more critical and then you have to

consider wind causing the scope to move a bit which can results in errors as

well.  Don’t forget about seeing conditions as well.

a 50mm finderscope should be ok.  I will be using a 30mm guidescope on a

C90 after planetary season ends this year.

 

You might want to download the beta version of PHD2, which allows for multiple

guide stars.

 

I would make sure my stars are very sharp in my guidescope.

 

JR

From: MAIN@ESPMC-Eight.groups.io [mailto:MAIN@ESPMC-Eight.groups.io] On Behalf Of kevin power
Sent: Saturday, June 12, 2021 5:31 PM
To: MAIN@ESPMC-Eight.groups.io
Subject: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2

 

Hi all i have had my mount just under a year now with no real issues. 

Generally use ED80 with ZWO 290mc camera and guide scope and can easily get 300 seconds and 600 second images after a decent polar alignment.

I now have a 200pds, 8 inch newtonion and can not use on this mount? Phd2 can not control the mount at all my total guiding is about 50 but goes higher.

I use the same 50mm guide scope could this be too small or is the mount just not capable of a telescope this size?

Is there anything I can try setting wise?

Thanks for any help


kevin power
 

Thanks for your reply

 

I had excellent polar alignment according to Sharpcap and balance was as good as I could get due to guide scope being off center, maybe I could rotate more to balance out better?

 

I use the same guide scope as I do on the ED80 and have multi star guiding set up in PHD2.

 

I assumed that as I was using the same guide scope I wouldn’t need to change any settings in PHD2 but im guessing that is not the case? Would this be because of the positioning of the guide scope on the main telescope eg guide scope is now much further forward and would alter the signal to the mount?

 

Sounds like I need to do more research into PHD2 settings and hopefully can save more than one setup so to not have to recalibrate every usage.

 

The 2 times I have tried the 200PDS have been clear calm nights with no noticeable wind so I do not think this is the issue and have also seen videos of the EXOS2 handling large loads so felt safe getting this one.

 

Thanks

 

Kev

 

Sent from Mail for Windows 10

 

From: jrichard333 <jrichard333@...>
Sent: 13 June 2021 01:43
To: MAIN@ESPMC-Eight.groups.io
Subject: Re: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2

 

Howdy,

 

Just so you know up front, I mostly do planetary imaging.  I’ve dabbled a

little into DSOs.

 

I don’t think it’s the mount.  The EXOS-2GT PMC8 can hold a lot of weight.

I’ve seen it handle over 80Ibs (36kg).  I have an iEXOS-100 with the  ST3

tripod legs and it can easily handle 20Ibs (9.1kg) and the rating for this mount

is a lot less.   Just make sure you are balanced and you should be fine once

you develop new settings for PHD2.

 

You will have to start over using PHD2 (settings, etc.); why, you are going from:

  1.  a small foot print (ED80) to a larger foot print (200dps) scope
  2.  a shorter focal length (480mm) to a longer focal length (1000mm)

 

Higher focal lengths make alignment a bit more critical and then you have to

consider wind causing the scope to move a bit which can results in errors as

well.  Don’t forget about seeing conditions as well.

 

a 50mm finderscope should be ok.  I will be using a 30mm guidescope on a

C90 after planetary season ends this year.

 

You might want to download the beta version of PHD2, which allows for multiple

guide stars.

 

I would make sure my stars are very sharp in my guidescope.

 

JR

From: MAIN@ESPMC-Eight.groups.io [mailto:MAIN@ESPMC-Eight.groups.io] On Behalf Of kevin power
Sent: Saturday, June 12, 2021 5:31 PM
To: MAIN@ESPMC-Eight.groups.io
Subject: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2

 

Hi all i have had my mount just under a year now with no real issues. 

Generally use ED80 with ZWO 290mc camera and guide scope and can easily get 300 seconds and 600 second images after a decent polar alignment.

I now have a 200pds, 8 inch newtonion and can not use on this mount? Phd2 can not control the mount at all my total guiding is about 50 but goes higher.

I use the same 50mm guide scope could this be too small or is the mount just not capable of a telescope this size?

Is there anything I can try setting wise?

Thanks for any help

 


 

Kevin,
 
We do have members here using both larger and longer-FL scopes successfully, so it can be done, but with this mount's hardware, technique will play a role.  
 
I'm just switching up from a 4" refractor to a 130PDS, and I have work to do on mine as well.  I do notice the change.  The weight is up by only about 3 lbs with all my 'stuff' attached, but even the petite 130 is bulkier than my refractor, so moment arm/leverage/balance is much different.  
 
I helped with the recent Beta and had some early issues, so my carefully-adjusted gears are off a bit.  Time to break out the hex wrenches and do a tuneup, once I get past coma corrector spacing, tilt, and collimation issues with the new scope.  In the meantime, even if I'm not entirely happy with my numbers from PHD2, my stars are still round, and that's what really what matters.
 
FWIW, the usual recommendation for camera and guidescope positioning is 6 o'clock and 12 o'clock, respectively.  I have tried other positions, and while I don't like 6-and-12 (because reasons), that does seem to be least-worst for balance.  I also ordered an accessory bar for the top, so I would have more freedom to move the guidescope fore-and-aft for balance.
 
Hope this helps...
 
- Bob
  
--
Mounts: ES PMC-8 EXOS2, Serial
Scopes: SW 130P-DS, SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM 6.3, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


kevin power
 

Good to hear that there is success maybe I won't give up with it yet.

Guide scope to camera is probably something like 2 and 6 so sounds like I need to make a bracket so I can mount 6 and 12.

I am still on the original PMC8 firmware duento reading about issues with the update but due to work I have not had much te to look into it properly, so much to learn.

Next steps must be guide scope positioning and PHD2 set up and see what happens.

Thanks

Kev


From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> on behalf of Robert Hoskin <devonshire@...>
Sent: Monday, June 14, 2021 11:02:52 PM
To: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io>
Subject: Re: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2
 
Kevin,
 
We do have members here using both larger and longer-FL scopes successfully, so it can be done, but with this mount's hardware, technique will play a role.  
 
I'm just switching up from a 4" refractor to a 130PDS, and I have work to do on mine as well.  I do notice the change.  The weight is up by only about 3 lbs with all my 'stuff' attached, but even the petite 130 is bulkier than my refractor, so moment arm/leverage/balance is much different.  
 
I helped with the recent Beta and had some early issues, so my carefully-adjusted gears are off a bit.  Time to break out the hex wrenches and do a tuneup, once I get past coma corrector spacing, tilt, and collimation issues with the new scope.  In the meantime, even if I'm not entirely happy with my numbers from PHD2, my stars are still round, and that's what really what matters.
 
FWIW, the usual recommendation for camera and guidescope positioning is 6 o'clock and 12 o'clock, respectively.  I have tried other positions, and while I don't like 6-and-12 (because reasons), that does seem to be least-worst for balance.  I also ordered an accessory bar for the top, so I would have more freedom to move the guidescope fore-and-aft for balance.
 
Hope this helps...
 
- Bob
  
--
Mounts: ES PMC-8 EXOS2, Serial
Scopes: SW 130P-DS, SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM 6.3, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Paul Mogg
 

Hi Kev, After about 6 months with the EXOS2-PMC8 and a 200DPS scope, my experience is that it is possible to get good guiding with this setup, I frequently get 0.80" total error on PHD2. ..but it is very inconsistent. Exact balance seems to be everything, and changes with the side of pier you're on, the wind conditions etc.etc. If you look at the attached pic I am using the 6 -12 camera-guide scope setup mentioned in other replies, and I've put a strengthening extra bar on top, where I've mounted my 50mm guide scope towards the rear.  I'm still learning, and it's tough. I've never had a smaller profile telescope, but my impression is that the larger the profile of the telescope, the larger, heavier and more robust the mount needs to be, irrespective of weight. Especially if you don't have a dome of any sort to protect from wind effects. Newtonians are natural sails. This would all seem to be common sense that fits with the laws of physics, and I will probably eventually swap out this mount for something more meaty to use with the Newtonian, or just use it with a smaller profile scope. I now only do max 60sec exposures, and find I can eek out the most usable frames from that, I usually have to dump about 20% of the frames I shoot. I've tried longer exposures with little success. But I get pretty good results for my efforts, I attach a pic of M51 I did with this setup 2 nights ago. It's 2 hrs 38mins of LRGB monochrome all in 60sec shots. Just my two cents worth. Good luck.

Cheers,

Paul
--
Location: southern Spain

Equipment:
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
ZWO 1600mm PRO monochrome camera
Orion 50mm guide scope
Oriion Starshoot guide camera
ZWO EAF 
Telrad.
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Macbook Air 
Huawei Android T5 Tablet
Software: Kstars / EKOS, ExploreStars Android & WIndows, Stellarium, AstroDSLR.


kevin power
 

Brilliant I have an extra bar so will attach it like yours I just need an adaptor for the guide scope mount.

I'd be happy to get 60 second shots so next time the clouds are gone I will give it a go

Is there any settings in PHD2 that you use or just calibrate to the set up?

Thanks

Kev


From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> on behalf of Paul Mogg <pdmogg@...>
Sent: Tuesday, June 15, 2021 10:30:03 AM
To: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io>
Subject: Re: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2
 
Hi Kev, After about 6 months with the EXOS2-PMC8 and a 200DPS scope, my experience is that it is possible to get good guiding with this setup, I frequently get 0.80" total error on PHD2. ..but it is very inconsistent. Exact balance seems to be everything, and changes with the side of pier you're on, the wind conditions etc.etc. If you look at the attached pic I am using the 6 -12 camera-guide scope setup mentioned in other replies, and I've put a strengthening extra bar on top, where I've mounted my 50mm guide scope towards the rear.  I'm still learning, and it's tough. I've never had a smaller profile telescope, but my impression is that the larger the profile of the telescope, the larger, heavier and more robust the mount needs to be, irrespective of weight. Especially if you don't have a dome of any sort to protect from wind effects. Newtonians are natural sails. This would all seem to be common sense that fits with the laws of physics, and I will probably eventually swap out this mount for something more meaty to use with the Newtonian, or just use it with a smaller profile scope. I now only do max 60sec exposures, and find I can eek out the most usable frames from that, I usually have to dump about 20% of the frames I shoot. I've tried longer exposures with little success. But I get pretty good results for my efforts, I attach a pic of M51 I did with this setup 2 nights ago. It's 2 hrs 38mins of LRGB monochrome all in 60sec shots. Just my two cents worth. Good luck.

Cheers,

Paul
--
Location: southern Spain

Equipment:
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
ZWO 1600mm PRO monochrome camera
Orion 50mm guide scope
Oriion Starshoot guide camera
ZWO EAF 
Telrad.
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Macbook Air 
Huawei Android T5 Tablet
Software: Kstars / EKOS, ExploreStars Android & WIndows, Stellarium, AstroDSLR.


 

Kevin,
 
When I was using my refractor for imaging, my rule was basically:  balance first, then bias weight to RA: East-heavy and DEC: camera-heavy.  For the 130, I've carried that forward as East-heavy, Primary-heavy.  The EXOS-2 will always balance a bit lopsided, thanks to that DEC motor, but there's no point fighting that.
 
My suspicion (once I'm done fooling with other things), is that I will find that due to increased sail area, I'll need to bias East-heavy, more aggressively than I did with the refractor.  Remains to be proven, so just "FWIW".  
 
The other thing I have just started to do is take Jerry's advice on polar alignment, and leave some deliberate error.  This (combined with weight bias), to try to force DEC to guide in one direction, and minimize backlash effects.  I had already reduced PHD2's sensitivity for DEC, as it had become clear that corrections on one axis could sometimes induce errors and corrections in the other, leading to back-and-forth between them.  The seeing in my location is not great, so for me, at least, less guiding is more (and yes, multi-star PHD2 is a good thing).
 
Hope this helps.
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2, Serial
Scopes: SW 130P-DS, SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM 6.3, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


kevin power
 

Thanks Bob more for me to try but must ait I made guiding more aggressive but that did nothing, never crossed my mind to try making it less aggressive!

So you suggest a rough polar align rather than spot on? I set mine up in the same spot every time and have to make some adjustments so maybe next time I will leave as is? I have done this in the past with the ED80 and seemed to work fine but I never realy have issues with that on the mount.

Next clear night I have a few things to try now with PHD2 and balancing so hopefully will get somewhere with it.

Thanks

Kev




From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> on behalf of Robert Hoskin <devonshire@...>
Sent: Tuesday, June 15, 2021 1:48:47 PM
To: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io>
Subject: Re: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2
 
Kevin,
 
When I was using my refractor for imaging, my rule was basically:  balance first, then bias weight to RA: East-heavy and DEC: camera-heavy.  For the 130, I've carried that forward as East-heavy, Primary-heavy.  The EXOS-2 will always balance a bit lopsided, thanks to that DEC motor, but there's no point fighting that.
 
My suspicion (once I'm done fooling with other things), is that I will find that due to increased sail area, I'll need to bias East-heavy, more aggressively than I did with the refractor.  Remains to be proven, so just "FWIW".  
 
The other thing I have just started to do is take Jerry's advice on polar alignment, and leave some deliberate error.  This (combined with weight bias), to try to force DEC to guide in one direction, and minimize backlash effects.  I had already reduced PHD2's sensitivity for DEC, as it had become clear that corrections on one axis could sometimes induce errors and corrections in the other, leading to back-and-forth between them.  The seeing in my location is not great, so for me, at least, less guiding is more (and yes, multi-star PHD2 is a good thing).
 
Hope this helps.
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2, Serial
Scopes: SW 130P-DS, SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM 6.3, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Matt
 

Hello! 

As recommended by others, your biggest improvements will come from careful balance and achieving only 'Good' polar alignment. Your Aggression and MinMo settings in PHD2 usually only come into play when you're narrowing your margin of error. I'm currently using a 8" f/4 Newtonian with a 50 mm guide scope on the Exos2 as well and have had great results with guiding so far. My mount is tuned (Thanks R. Hoskin!) and I'm aware of the amount of backlash that is inherent in DEC which presents itself intermittently no matter what scope is mounted, however, the added weight of this large Newtonian (paying very close attention to balance) allows the mount to 'settle' nicely in my experience.

Ultimately, the biggest breakthrough I had with guiding, following the mount tuning, was when I followed the advise of others on this forum and intentionally backed off from 'Excellent' Polar Alignment to achieve only 'Good' alignment (using Sharpcap I get both axis to within :30 to :50). This allows PHD2 to send consistent guide pulses to both axis for correction and keeps the gears engaged which helps prevent the backlash from being introduced. With this in mind, I also decreased my exposure time to .5 seconds in PHD2 (when possible) to increase the amount of Guide pulses sent to the mount. The Exos2 responds well with these conditions. All mounts in this class suffer from a large amount of backlash in DEC. If you choose to use an 'Excellent' polar alignment, you will want to consider guiding in only RA and not DEC, however, I believe you'll find better results in DEC guiding without perfect polar alignment. 

To sum up; you should be able get perfect balance with the Newtonian by offsetting the DEC drive with the guide camera. You will improve guiding by getting only 'Good' polar alignment. Once you've ironed out these methods, you then can decide whether your mount prefers the scope to be Primary heavy, or, Camera heavy, as well as, your RA, either East heavy, or, West heavy dependent on the side of the meridian you're on. Once excellent balance is achieved and alignment set to a 'Good' result make sure to recalibrate in PHD2. Remember, the key is to have the gears engaged as consistently as possible. For the purpose of troubleshooting, try to get truly perfect balance on DEC without having it either Primary, or, Camera heavy, then get a 'Good' polar alignment and use the default settings in PHD2 just to see how it performs. From there you can shift weight to either Primary or Camera to check for improvements and allow the Guiding Assistant in PHD2 to suggest changes to your Aggression/Minmo etc. I'd be interested to hear your results. 

Good luck!
-Matt

------
Mount: ES PMC-8 EXOS2 - Serial
Primary OTA's: GSO 8" f/4 Newt / GSO RC6 / Meade 70mm Quadruplet 
Guide OTA's: Orion 50mm / Primaluce 60mm 
Cameras: ZWO ASI294MC / Canon T3i 
Software: Ascom / NINA / Sharpcap / PHD2 / Photoshop 
OS: Dell / Windows 10


Paul Mogg
 

On PhD2 you have to do some trial and error with the settings, and read their very good documentation on troubleshooting guiding issues. ..but the main things I find is that 1 sec exposure times give me better guiding than 3 sec, and the new Multi-star guiding gives better results than the older single-star guiding, though it has a bug in it where it occasionally seems to switch back to single-star guiding and you have to un-tick and re-tick the multistage guiding option box in the settings to get it back.

If you're on a Mac, I have had great success with Ekos / Kstars for all the capturing / polar alignment tasks. Its' new polar alignment routine seems very accurate, quick and easy to use, as is their plate solving. I often get polar alignment errors of only around 0.40" or less now.

Cheers,

Paul

--
Location: southern Spain

Equipment:
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
Nikon D5200 DSLR
Orion 50mm guide scope
Oriion Starshoot guide camera
ZWO EAF 
Telrad.
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Macbook Air 
Huawei Android T5 Tablet
Software: Kstars / EKOS, ExploreStars Android & WIndows, Stellarium, AstroDSLR.


kevin power
 

On PHD2 I have been using auto for exposure time, it seems there are a few settings I need to play with and test out.

I assumed that as it worked with the ED80 all settings would be the same as its the guide scope controlling the mount but seems I was way off the mark.

0.40 seems great, on a good day with the ED80 I get 0.70 ish but stars seem nice and round so happy with that.

Hopefully I will get out this weekend to try just depends on the clouds?

Thanks

Kev


From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> on behalf of Paul Mogg <pdmogg@...>
Sent: Wednesday, June 16, 2021 12:55:24 PM
To: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io>
Subject: Re: [ESPMC-Eight] Exos 2 PMC8 telescope size #EXOS2
 
On PhD2 you have to do some trial and error with the settings, and read their very good documentation on troubleshooting guiding issues. ..but the main things I find is that 1 sec exposure times give me better guiding than 3 sec, and the new Multi-star guiding gives better results than the older single-star guiding, though it has a bug in it where it occasionally seems to switch back to single-star guiding and you have to un-tick and re-tick the multistage guiding option box in the settings to get it back.

If you're on a Mac, I have had great success with Ekos / Kstars for all the capturing / polar alignment tasks. Its' new polar alignment routine seems very accurate, quick and easy to use, as is their plate solving. I often get polar alignment errors of only around 0.40" or less now.

Cheers,

Paul

--
Location: southern Spain

Equipment:
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
Nikon D5200 DSLR
Orion 50mm guide scope
Oriion Starshoot guide camera
ZWO EAF 
Telrad.
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Macbook Air 
Huawei Android T5 Tablet
Software: Kstars / EKOS, ExploreStars Android & WIndows, Stellarium, AstroDSLR.