View Single Post
Old 03-08-2020, 12:30 PM
Startrek (Martin)
Registered User

Startrek is offline
Join Date: Dec 2017
Location: Sydney
Posts: 2,602
Originally Posted by xa-coupe View Post
Thanks for a comprehensive reply!

1. - yes. It does work for a while. It also connects fine at startup.
2. - guide camera is pretty standard, ZWO ASI 120MM-S.
3. - Calibration ... err.. maybe I missed that.. I'll have to look into that.
4. - Yes.
5. - yep.. tried 1 sec, 2 sec and 5 sec .. all to no avail.
6. - yes.
7. - No. From what I have read and seen, the current 'go' is directly to the PC via the handset.
8. - No hubs for that.
9.- definitely a USB 3.

I'm wondering if the calibration is the key. I believed it calibrated when the software started up ... I must have missed the details. Certainly worth a try.

I also suspect the mount. I seem to have some 'weirdness' with it. Sometimes it seems to think the targets are 20 degrees off where they are, after a 2 star alignment followed by a polar alignment. Even a poor alignment shouldn't throw that sort of error.

thanks again.
One question I forgot to ask , are you using a software based Goto and tracking program like EQMOD or just using the handcontroller to navigate ?
If your mount is a Skywatcher eq5 , HEQ5, EQ6 or EQ6-R I’d recommend you take advantage of eqmod which is a free open source Goto and tracking program. It also allows you to use PHD2 pulse guiding ie: laptop direct to guide camera. The developers of PHD2 recommend this way of guiding
“Calibration” amongst other things is probably the most important part of setting up your guiding. The bottom tool bar indicates your status including calibration ( a green symbol Cal is indicated )
I recommend you read the PHD2 manual to grasp the fundamentals of guiding

Here’s some more tips on PHD2 guiding from my library -

PHD2 Set Up and Guiding tips

1/ Try to Polar align to around 1arc minute error on Alt and Az

2/ “Auto select guide star” (recommended by PHD2) or manually select star that’s not too bright or saturated to avoid lost stars

3/ If guiding is poor ( above 2 arc seconds ) utilise the Guiding Assistant

4/ Check and adjust focus of your guide scope and camera to minimise lost stars

5/ Set your guide camera exposure time between 2 and 4 seconds ( Looping ) 2 seconds is a good starting point

6/ The SNR value of the guide star should be between 15.0 and 40.0 to avoid losing the guide star

7/ Don’t over correct settings , under correcting will let you manage your guiding performance better

8/ If Guiding is poor try and keep your min mo above 0.25 in RA and DEC . Don’t go above 0.6. A good starting point for min mo is 0.20 or 0.25

9/ Important- Build a Dark Frame library and a Bad pixel map to provide good calibration and stable guide star. PHD2 will only allow you to use one or the other

10/ The RA Osc value should be between 0.3 to 0.5
If it drops to 0.1 or lower then increase the RA aggressiveness or decrease the hysteresis
If it gets quite high say 0.8 then reduce the RA aggressiveness or increase the hysteresis

11/ Use Ascom Guiding - Laptop direct connect to mount ( preferred by PHD2 Developers) in lieu of ST4 connected guiding via camera to mount

12/ USB 2 cable to camera is not to exceed 5 metres

13/ Try and avoid cabling through a hub even a Powered hub, direct connect to the computer , you will have less issues

14/ Ensure you have the latest driver installed for your guide camera

15/ If guide camera is USB2 make sure you connect into a USB2 port with USB2 cable
If the guide camera is USB3 it most probably will connect with a USB2 cable

16/ Ensure you enter all the correct data for your guide camera into PHD2 brain tabs

17/ Make sure you get good Calibration. Calibrate within 10deg of celestial equator and within an hour of meridian
Once Calibrated save it and reuse it ( go to Brain in guiding tab and tick box “Auto restore Calibration”)

18/ if you lose guide star often , go to Brain in guiding tab and increase “Search region” and increase “ Star mass detection”
Reply With Quote