Date   

Re: Guiding issues Exos2Gt PMC8 #EXOS2

Mark Christensen
 

Hi, a couple of things:

1. Please sign your postings. Perhaps it is under the image? Anyway, it is a good idea to do sign all postings.
2. What units are you expressing you guiding error in? Pixels or Arc Sec (")? Please indicate that.
3. How long is your guiding exposure? If you took the defaults it is probably 2 or 3 seconds. If it is much shorter then you may be 'chasing seeing'.
4. How tight was your focus on the guide star? If it is too good then the guider may be jumping from one edge to another. I've seen that happen. Soften up the focus just a tad - the algorithm computes a centroid of the image of the guide star. You also don't want the image saturated.
4. Did you evaluate the DEC drift (DEC guiding OFF). If there is little drift (many guiding exposures to see if there is a trend) then it looks like you have (unavoidable) backlash in the DEC and very good polar alignment. That means when the guider sees the curve go on one side it may be overcorrecting in the other direction. Then the guider sees the overcorrection and tries to go back the other way, producing overcorrection in the other direction. That appears to be what is happening.

So I'd do the following next time:
A. Turn off DEC guiding and see if there is much drift - a definite trend line in one way or another.
B. If there is much DEC drift, say NORTH at a 1/2 pixel (about 2 arc sec) in a couple of guiding exposures. with your rig, then in the DEC Algorithm Tab set it to SOUTH only. If the drift is to the SOUTH, set the DEC Algorithm to North Only Similar to biasing the weight of the RA axis, this avoids the motor reversing which results in backlash.
C. If you see no meaningful DEC drift then your polar alignment may be too good.  Sounds backwards, right? If the polar alignment is really good with no DEC drift then the mount is probably being driven into oscillation by the guider. See note 4 above. Aside from buying a much more expensive mount with much less intrinsic backlash (there is always some, hence the trick of biasing the RA - it avoids the RA trying to reverse direction) this is often the only cure -introduce a tiny amount of polar drift and then set the DEC algorithm to only go in one direction.
D. It is possible the DEC gears are set too tight or loose. Since I don't have the PMC I can not advise you. With virtually every mount I have had or worked on (including a non-PMC G11, a CGEM, a AP800, a CG5-AST, and the older non-PMC  EXOS2GT) I've had to do some adjustments to improve guiding. But then I am imaging, usually, at 1100mm focal length with my G-11. With the CG5 at 750mm, with the EXOS-2GT at 400mm. With normal camera lenses (below 200mm) you should be fine not matter what.

You didn't say if your pictures were OK or not, by the way. That is what matters, not the PHD2 graph by itself. If you are using nominal camera lenses even 10 arc second of peak-to-peak (more relevant than RMS) would be tolerable.

Finally, make sure it you don't have cable drag in the DEC direction or a loose mounting of the camera to the guider. Those are unlikely to be the problem since you are only seeing the oscillations in one axis. But you never know.

Regards,

Mark Christensen


On Thursday, August 29, 2019, 8:15:09 AM UTC, JB1983 <capnjake83@...> wrote:


So a couple weeks ago I finally completed my rig.
Been out with it twice so far and I'm trying to find some insight as to why my guiding is so bad.

Exos2GT PMC8 mount, ASI120mm mini and using a 60mm f4 guidescope.

Polar alignment in sharpcap goes well.  PHD2 finds stars no problem.  Running POTH with stellarium and stellarium scope.
My imaging camera is a dslr, and I find it easier to unlock the clutches and move the scope by hand to do my 3 or 4 star alignments.

Everything is working well and communicating well.

60 second exposures, no star trailing.

The first time out I balanced the RA and Dec evenly. Had a total RMS of .75, but the graph was all over the place.
Tonight since inwas imaging to the west, I tried the easy bias balancing. Sold my counterweight up a pinch and my total RMS was over 3.00.  RA was good at .59, but the dec was at 3.92.

Currently using the default parameters in PHD2.

I'm just wondering, is there something special I'm not doing to make this mount guide correctly?   If not, I'll go out again here soon and try it all again.  Any help would be appreciated.
Thanks 


iexos 100 #iEXOS-100

ettore.ribaudo@...
 

Good morning Sirs my name is Ettore Ribaudo and I receveid yesterday my mount but I have big problem:
1) USB have a random problem with connect.
2) wifi functions good.
3) mount not move in nothing direction.
4)i tried with app explorer but see for ten minut "I wait"
Alimentation mount with battery. 
My pc is a laptop with Mac and bootcamp. 
Sorry for my English. 
Ettore


Guiding issues Exos2Gt PMC8 #EXOS2

JB1983
 

So a couple weeks ago I finally completed my rig.
Been out with it twice so far and I'm trying to find some insight as to why my guiding is so bad.

Exos2GT PMC8 mount, ASI120mm mini and using a 60mm f4 guidescope.

Polar alignment in sharpcap goes well.  PHD2 finds stars no problem.  Running POTH with stellarium and stellarium scope.
My imaging camera is a dslr, and I find it easier to unlock the clutches and move the scope by hand to do my 3 or 4 star alignments.

Everything is working well and communicating well.

60 second exposures, no star trailing.

The first time out I balanced the RA and Dec evenly. Had a total RMS of .75, but the graph was all over the place.
Tonight since inwas imaging to the west, I tried the easy bias balancing. Sold my counterweight up a pinch and my total RMS was over 3.00.  RA was good at .59, but the dec was at 3.92.

Currently using the default parameters in PHD2.

I'm just wondering, is there something special I'm not doing to make this mount guide correctly?   If not, I'll go out again here soon and try it all again.  Any help would be appreciated.
Thanks 


Re: First Image with the new mount! #iEXOS-100

brian skinner
 

Many thanks again Julien. I'm waiting for clear skies now but will see how I go with just my DSLR and Sequator (which appears to be loaded successfully),
Kind regards, Brian 


On Tue, 27 Aug 2019 16:51 julian.shroff1 via Groups.Io, <julian.shroff1=googlemail.com@groups.io> wrote:

[Edited Message Follows]

Hey Brian, 

I use Lightroom to pre-process my lights, I use the lens profile of my lens to remove the vignetting and apply some small steps like reducing the highlights and the blacks to get rid of bloated stars/background noise.

There are many people who swear on leaving your lights untouched, in my opinion that doesn't matter when using DSLR's but hey, it's a never ending discussion. Alternatively you can use something like Adobe dng converter, it's free as far as I know. 


Re: First Image with the new mount! #iEXOS-100

julian.shroff1@...
 
Edited

Hey Brian, 

I use Lightroom to pre-process my lights, I use the lens profile of my lens to remove the vignetting and apply some small steps like reducing the highlights and the blacks to get rid of bloated stars/background noise.

There are many people who swear on leaving your lights untouched, in my opinion that doesn't matter when using DSLR's but hey, it's a never ending discussion. Alternatively you can use something like Adobe dng converter, it's free as far as I know. 


Re: First Image with the new mount! #iEXOS-100

brian skinner
 

Hi Julian many thanks for this, much appreciated. I had problems loading DSS unfortunately I think because I have an older 32 bit PC. I presume DSS requires a 32 bit platform.
I have now successfully loaded the last Sequator 32 bit version so will try this for my stacker. One question I do have if I may; how do you convert the camera RAW files to TIFF files? Both DSS and Sequator require or recommend this for successful processing.....
Any help on this would be appreciated Thank you, Brian, 

On Mon, 26 Aug 2019 11:00 julian.shroff1 via Groups.Io, <julian.shroff1=googlemail.com@groups.io> wrote:
Hey Brian,

for astrophotography standards, I'd say DSS is very intuitive. There are a good bunch of tutorials on the web on how to use it, but basically all you have to do is put in the light (and dark/flat/bias if you wish so) frames and let it do the work.

Here's a short excerpt of a small astrophotography guide I'm writing, it's not even close to being complete but it might help you :)


Import the .TIF Files as Lights into DSS

WHEN USING MODERN DSLR + LENS: NO DARK/BIAS/FLAT FRAMES  NEEDED !! (assuming you pre-processed the raw frames and converted them to .TIF files)

Register checked pictures -> Select Best 85% ; Advanced -> Compute number of detected stars, should be ~100-200

Set stacking parameters → Kappa-Sigma Clipping

Save as 16-Bit TIF (Save picture to file…) Make sure not to use the Autosave file (It’s 32bit)


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Darryl Ellis
 

Outstanding.

I've recently gotten five minutes subs and I too am very impressed and satisfied with my mount performance.

I'm sure it could do twice that amount or more time permitting.

Darryl
--

DHEllis59, Dover, DE
Astro Tech RC 6 w Pegasus Focus Cube,
Orion Starshoot II Pro Imager,
QHY 5 II Guide Camera and 30mm Guidescope,
Explorer Scientific EXOS GT 2 With PMC Eight Controller,
Orion XT8 with Nexus II DSC via Sky Safari Pro,
Celestron Luminous 31mm, Meade MWA 10mm, and 5mm EPs
Celestron Skymaster 15x70 binoculars,
20/20 or better vision in both eyes due to recent cataract surgery!!!
"The LORD by wisdom founded the earth, By understanding He established the heavens" - Proverbs 3:19


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Jim McKee
 

Beautiful shot Bob. 10 minutes is terrific! 
--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Astro Mod, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. Backyard EOS, StarTools, APT, DSS
Computer:  Dell Latitude E5450, Windows 10


Re: UPDATED VIDEO: New Video on How To Install and Configure the ASCOM Driver for the iEXOS 100 Mount #ExploreScientific #iEXOS-100

asanmax@...
 

Wes

Amazing! Just tried to connect and test the mount from APT. Exactly what I needed for slow motions and framing. Problem solved! Hope it's going to be a clear night for further testing.


Re: UPDATED VIDEO: New Video on How To Install and Configure the ASCOM Driver for the iEXOS 100 Mount #ExploreScientific #iEXOS-100

Wes Mcdonald
 

Asanmax

I have APT up and running great.  It does a wonderful job with the plugins of plate solving. It also integrates well with Stellarium via stellariumscope too.  So you should have no issues.

Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Re: UPDATED VIDEO: New Video on How To Install and Configure the ASCOM Driver for the iEXOS 100 Mount #ExploreScientific #iEXOS-100

asanmax@...
 

Thanks for the information Bob. Unfortunately I am not planning to use Astrotortilla. I see there is an option to connect to the mount in Astrophotography Tool. I'll give it a try and see if I can slew the mount from withing the application.


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

 

Good!   

Just wondered - there was more than one thing going on in the post :-)

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Raymond Shaw
 

I have the EXOS2 PMC8 mount but have not stepped up to guiding yet. 
I’m impressed with your results.
Being a relative beginner, I’ve been happy with what I’ve been able to do unguided after a good polar alignment


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

 

On which part?  :-)

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Raymond Shaw
 

That is great! I’m sold!


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

 

And...

Here's a first-cut try at processing the stack from that session.    

12 X 600s used, plus flats and dark flats, stacked in DSS and processed in StarTools.  Lots of room to do better (both capture and processing), but much better than I was getting before the filter.

No idea whether 600s is the sweet spot for my gear and targets like this, or whether there's a more optimal setting, but it was a kick to see that the mount just handled it and wasn't a limitation. 

- Bob







--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

 

Eric,
 
You can do a lot with 5 minutes at 300mm - that's great!
 
Thanks!   No, it's faster than that.  Mine's a 102/621mm.
 
I started out with a 50/200mm guide scope, and on Jerry's advice went to a 60/280mm.  That helped considerably.
 
My guide camera, well...  
When I picked it, I had no idea and just wanted 'something to guide with', so I went for versatility and ended up with an Altair GPCAM2 IMX224 Color, with 3.75um pixels.  Just the thing for shooting Jupiter with, but not what I'd pick for a guide camera, if I had to do it all over again. One of these I'll probably switch it out for something IMX290-based and mono, w/2.9um pixels - and that should give me another bump. 
 
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

 

Cybermonk,
 
Absolutely - but as to discouraging posts, it's all about expectations. :-)
 
The mount, with out-of-the-box adjustments, will likely track fine for visual users.  Putting a camera on one changes the game, and requires the operator to be more involved in the mount's tracking performance.
 
When I first got my mount, I was pretty disappointed that just by plunking it down and turning it on, I didn't get good tracking.  And, like many, I expected that good UN-guided performance was a prerequisite for good guided performance later. Both wrong, as I found out. 
 
I ended up going over the tripod, mount head, and power train, looking for things that contribute to mechanical tracking errors.  Basically, a collection of seemingly small things, but when I found  and corrected them, it made a big difference.  Those out of the way, the PMC8 is fast enough that it can then guide out remaining mechanical errors to the point where, when operated with care, the mount can perform far better than you'd expect for its price point.  
 
It was enough work chasing down those small things, that I figured I'd better document them and save others the trouble - my notes are over in Mounts/Files, if anyone needs them.     
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Eric Harant
 

Congratulation Bob,
Your focal length is 714mm, is't it ?
With camera do you use for guiding ?

I begin to get descent shot at 5minutes with a 300mm F/5.6 canon lens.
Guiding with a 60/240 scope and a ZWO 120MM.

Best regards
Eric


On Sun, Aug 25, 2019 at 08:32 PM, Robert Hoskin wrote:
SV 102EDT

 
--
Eric
Nargis (45) France.

57 years old, Computer science engineer.
Some skills in sofware development (Windows / Unix)
Canon EOS 10D, 40D, 600D 1300D, EOS-R. + several lenses.
ToupTek IMX 294 cooled camera.
ZWO ASI120MM
BRESSER Messier AR-102xs/460, Bresser Messier AR-152S/760
Orion 80ED.
MAK INTES 713.
Meade LX200 GPS 10"
Old Losmandy G11.
SvBony 60mm x 240mm guide scope.


Re: Ten minute subs with an EXOS2 PMC8! #EXOS2 #astrophotography

Cybermonk
 

I'm finally getting time to learn and play with my new-ish  mount. I have been reading some discouraging posts about length of exposures, Its good to know that once I get it right, there is something to look forward to. :)

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