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PHD2 -- M64 Blackeye Galaxy -- Success/Failure

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#1 The Cat

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Posted 06 May 2021 - 11:44 AM

Hi all, 

 

Thanks so much for all your help with getting started with PHD2. I used it for the first time under the sky last night and, at the end of the imaging session, I took a 10 minute exposure of M64 with PHD2 managing the guiding.

 

Here is the result: https://www.dropbox....0001_3.CR2?dl=0. I'm quite excited.

 

Not much in the way of star trails as far as I can see. In terms of setup and process, however, I'd like some advice. This is on a CEM70 mount; 80 mm Stellarvue refractor; Cannon EOS t7i camera; 800 ISO/10 min exposure; 50 mm guidescope; ZWO 290 mm guide camera. I hooked the camera into my HP laptop via USB. Hooked the laptop into the mount using a USB cable also. Used ASCOM software set to manage the CEM70. I slewed the scope to M64.

 

Initially, I had trouble achieving focus of the guide camera. I had to use the extender and pull the camera all the way back until it almost fell out.  How important is focus? Is there a different way to achieve focus than pulling the camera forward and back and then using the screws? Anyway, I then looped the images at 1s exposure and auto selected the star. I hit the green circle button and it started to calculate the whole West, East, Backlash etc. All the while the star moved away from the crosshair center and then moved back. After a while, the lower field read "guiding" and the graph started to generate the red and blue lines. Those lines were really wild with each hump basically going from the center line to the top and bottom of the screen! But the guiding seemed to work. I used all the default settings.

 

How do I get a log for you guys to view? When I go into the open log window under HELP, I can only see three EXPLORER files that identify failures to lock onto the autostar selection (something that happened at the very beginning of the imaging session before I had focus).

 

Any suggestions on what I have to look out for and how to bring those "humps" down closer to the centerline? I hope I wasn't chasing the seeing.

 

I must admit that I'm blown away by how sharp the stars are in that 10 min exposure. The CEM 70/Stellarvue typically gives me 3 minutes of unguided imaging with minimal star trails. But 10 min would be impossible.  



#2 The Cat

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Posted 06 May 2021 - 12:11 PM

Here is the guide log.  I downloaded PHD2 Logviewer. The graph doesn't look as insane when I open the attached file in it. Still, I'd love your input please. 

Thanks!!

 

Felix

Attached Files



#3 StephenW

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Posted 06 May 2021 - 01:27 PM

Just fyi: Looks like your guide scope is configured incorrectly in PHD2 - you have it configured as a focal length of 50mm, but 50mm is more likely it's diameter, not focal length.

 

As a result, PHD2 is reporting the wrong scale for corrections, and also thinks you're guiding at 12a/s per pixel.



#4 Mike in Rancho

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Posted 06 May 2021 - 06:29 PM

What kind of 50mm guidescope?  Most I have looked at come with a 1.25 helical focuser on the end, or at least a slide tube, sometimes both.

 

Focus of it can be done using something like Sharpcap.  Use a distant pole or mountaintop in the day to get it ballpark, then adjust on a star at dark.  It can probably be done in PHD2 also, temporarily selecting a faster exposure, and also from one of the menus (maybe view or tools, I forget) you can select star profile, which will give you a zoom of it plus FWHM and a little spikey-shaped graph.



#5 Desertanimal

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Posted 06 May 2021 - 07:42 PM

The guide scope “shroud” on the front may also be threaded and can be moved forward, away from the camera so you can put the camera in without it falling out.
1 sec loops in phd is also pretty quick, I usually use 2.5. Not that there is a correct answer.

Edited by Desertanimal, 06 May 2021 - 07:45 PM.


#6 Between17

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Posted 07 May 2021 - 01:09 AM

Agree with others 50mm is most likely not the correct focal length of your guidescope, you should set it to the correct value in PHD2.

 

In general the advice is to use a longer exposure time than 1 sec. Although your later sessions did use 2 sec.  I generally go with 3 sec.

 

I also wonder why you calibrated almost 30 times over the course of the evening? Your calibration in section 3 looked acceptable, why did you not just run with that for the whole night?

 

Did you run the Guiding Assistant after the calibration to establish some of the basic parameters including to measure the DEC backlash in order to set the backlash compensation? I think that is considered best practice to do so.



#7 michael8554

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Posted 07 May 2021 - 07:40 AM

Hi The Cat

 

Many of your settings are wrong, so before your next try, you need to read some of the PHD2 Help and How To instructions in the PHD2 Help Menu.

 

Exposure, Dec position for Calibrating, Guidescope focal length and focus, Backlash.

 

https://openphdguidi...n/Basic_use.htm

 

https://openphdguidi...-best-practices



#8 The Cat

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Posted 07 May 2021 - 07:43 AM

Hi — thanks for the great comments. As an initial matter, I made a mistake about my guide scope and will make the adjustment in Phd for my next outing. It’s actually a 30 mm, mini guidescope, with a focal length of 120mm. Does that guidescope have focusing capabilities on the tube, or do I just have to keep sliding the camera in and out until I achieve focus?

Also, Between 2017, I also can’t believe I calibrated 30 times!! Really, is that what the log says? But I did calibrate multiple times. I don’t think I understand the difference between calibration and selecting a guide star. I set the OTA on the target and then went through the process of looping, auto selecting a star and guiding. Every time the star was lost or the computer crashed, after the meridian flip, or I messed with the telescope in anyway, I restarted PHD2 and went through those intro steps again. Am I doing that wrong? If I don’t do it that way, can I just hit guide when I have start over?

#9 Desertanimal

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Posted 07 May 2021 - 08:12 AM

It may have a focus tube on the front. You haven’t said what brand your guide scope is. If it’s the typical 30mm scope then yes, the shroud should screw in and out to focus.

#10 StephenW

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Posted 07 May 2021 - 10:40 AM

>Am I doing that wrong? If I don’t do it that way, can I just hit guide when I have start over?

 

As you are using an ASCOM connection to your mount you only need to re-calibrate if your guide set-up changes.   This could include moving/rotating the guide scope, moving/rotating the guide camera (e.g. if you are trying to focus it), if you set-up and tear down each night etc. 

 

If you're not changing your guide set-up, then once you have calibrated you can continue to use the same calibration all night, or even longer - my permanent set-up only get's recalibrated every 6 months or so, assuming I haven't adjusted the guide set-up.



#11 hfsarber

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Posted 07 May 2021 - 11:06 AM

It sounds like it might be this one:

 

ZWO30f4.jpg

 

It was a struggle getting the lock ring loosened the first time.  And, I had to turn it at least 30 revolutions to get it to come to focus.  And, And, you have to fidget with it when tightening the lock ring.  It will change focus if not careful.

 


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#12 michael8554

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Posted 07 May 2021 - 12:00 PM

"I don’t think I understand the difference between calibration and selecting a guide star."

 

Calibration is a vital part of getting good guiding.

 

Any error messages need sorting before trying to guide.

 

In Calibration PHD2 moves the mount a set number of steps West and North.

 

It measures how far the mount has moved, and in which directions.

 

It now knows what size of guide pulses to send for your particular mount.

 

You can start a new Calibration by a Shift/Click on the Guide button.

 

Your guidecam might not be orientated with the long side of the sensor to the north. It doesn't matter, that's something PHD2 works out during Calibration.

 

Selection of a suitable guide star, or guide stars if you're using Multi Star, is best left to PHD2 with the AutoSelect button.

 

PHD2 doesn't want a star that is out of focus, over-exposed, or too dim, or too close to another star.

 

You can adjust your focus to get the lowest HFD figure on the PHD2 Star Profile window.

 

The guides I pointed you to will give you answers too.

 

"Every time the star was lost or the computer crashed, after the meridian flip, or I messed with the telescope in anyway, I restarted PHD2 and went through those intro steps again"

 

At any time you can stop PHD2 guiding by hitting the STOP button, no need to close PHD2.

 

The mount will continue tracking your target.

 

When you are ready again you Loop, AutoSelect, and Guide.

 

What do you mean by the computer crashed ?

 

The correct setting in PHD2 for Meridian Flip is explained in the Help guides.



#13 The Cat

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Posted 07 May 2021 - 04:36 PM

Okay, so now I am totally confused about calibration vs selecting a guide star. I’ve watched a bunch of videos and am still confused. This is my process. After choosing the équipement and hitting “connect all,” I get the stars in focus and loop the exposures. (I will make the exposures 2 seconds in future). I then hit auto select for the star. When I hit guide, the lower left row identifies a number of directional steps. West, North, South, Backlash correction, nudge etc. Once
done, Phd2 starts to guide.

I have never hit Shift Guide. Is that a problem? Sounds like Phd2 may be calibration on its own.

Separately, my laptop has issues. Sometimes it freezes or auto updates. It goes to standby too often and when I hit a key to get out of standby the computer sometimes restarts. I am looking for a new laptop. But, the result of this is that, whenever I have to start guiding again, I have to again loop,
Select star, and guide. Each time, the app goes through the whole West, South thing. In the close up viewer of the star, I can see the star drift with the steps and then get pulled back.

What am I doing wrong here? Should I not be selecting a star each time? I don’t see an alternative.

Thanks to those of you who identifies my guidescope. It is, indeed, the Zwo 30 mm mini.

I will fix the settings. Don’t know I made such a mess of this! How do I trigger the wizard again, so that I can adjust the settings for the equipment profile?

#14 StephenW

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Posted 08 May 2021 - 07:24 AM

Sounds like you do not have the Auto Restore Calibration setting enabled, and as a result PHD2 is re-doing calibration every time you try to start guiding.

 

Click on the Brain icon, then go to the Guiding tab and make sure Auto restore calibration is checked.



#15 michael8554

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Posted 08 May 2021 - 08:22 AM

Yes, normally Auto Restore is selected, we assumed that's how you've been running.

 

I would advise setting your laptop Power Settings to Always On.

 

Allowing it to go into Sleep, Hibernate, Standby etc in the middle of guiding is a Bad Idea.

 

Windows Updates can be set to install at a time of your choice, not in the middle of guiding.

 

So your laptop doesn't have issues, it's running perfectly the way you've set it up.

 

No need for a new laptop !

 

If you only want to change the focal length:

 

Press the "Brain" button on the bottom toolbar.

 

Select the "Guiding" tab.

 

In the Calibration area you'll find Focal length (mm).



#16 Normmalin

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Posted 14 May 2021 - 01:38 PM


Separately, my laptop has issues. Sometimes it freezes or auto updates. It goes to standby too often and when I hit a key to get out of standby the computer sometimes restarts. I am looking for a new laptop. But, the result of this is that, whenever I have to start guiding again, I have to again loop,
Select star, and guide. Each time, the app goes through the whole West, South thing. In the close up viewer of the star, I can see the star drift with the steps and then get pulled back.
 

You can change the settings on your laptop to never let the computer sleep or turn off the display.  Go to Control Panel - Power Options - "Change when the computer sleeps" and set the power settings so the computer does not sleep.




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