Skywatcher 200PDS on HEQ5 Pro .. what upgrades, if any

Hi Andy,

Below is my experience if at all helpful…

I have a 200 PDS and had a pretty similar setup at one stage with an HEQ5 that then went through some inexpensive and then other unfortunately much more expensive evolutionary changes.  I can't honestly say which single thing made the most difference but - in a general sense - I have monitored progress by a) montoring for improved guiding as measured by PHD2 in terms of the RMS arcsec  and b) looking to more consistently see lower FWHM arc sec values in my unstretched frames and images.  So e.g. Thames Valley UK is not normally great seeing but sometimes - with the mono camera -  I can get down as low as about 2.2 to 2.4  ..more typically 2.7 to 3.0 .  Very short frames (1 s) can get down to 1.8 or so.   

1) If you haven't done it already ..loosen off the mirror clips … it took me far too long to notice that my stars were somewhat triangle shaped seen close in. I think that the clips are generally tighter than they should be just for shipping?   Your stars look OK in fact as far as I can tell .

2) As mentioned above – scope balance in both axes and cable management - is really important and really took some time and desnagging to get right. – e.g. having the focuser pointing down and then twisting the tube within the rings a little until all is good.

3) Obviously collimation, secondary alignment etc. etc.  It helped I think to  leave it outside (covered) for a few hours to get down to temperature  and still have enough evening light left to collimate with a Cheshire etc.    Hotech laser is pretty good and essential in the dark but I still think that old-fashioned Cheshire is best.

4) Again obvious -PA adjustment. I learned to do it on the HEQ5 using the polar scope but it was a bit fiddly and currently I use an Ioptron ipolar which makes life easier (or Sharpcap is good too).  

4) A frequent autumn/ spring problem for me with the 200PDS has been dew —  not only the secondary but occasionally even the primary —also the guide scope objective— .  I tend to use a dew shield (originally intended for an 8 inch SCT)  and do sometimes resort to a 1 min blast with a hair dryer  - which normally keeps things clear for an hour or so

5)  With the camera and all on the original PDS focuser I just found it slipped -  which was annoying.  So I bought a Baader steeltrack Newtonian focuser and it was really a whole lot better. 

6)  However now a big expenditure—- and this really depends on exposure length and shelter from wind etc –  but I thought that the overall weight was going to be too much for the HEQ5-   So   I bought a heavier duty mount (Ioptron CEM70).

7)  Finally I looked to further improve the guiding by upgrading to an 80 mm,  f = 400 mm achromat sitting on a top bar across the tube rings (originally I had only an f= 160mm finder scope set up).  I think that this —as well as using PHD2 in it s multistar mode - helped get the guiding down to within 0.5 arcsec RMS on a good night

Definitely agree that dark skies and learning more about processing are also just as  key.  Worth holding on to the old data because as your knowledge of processing grows it often becomes worth revisiting.

Overall I don't think that the 200PDS itself (part from the focuser) has ever been the limiting factor in the quality of any of my images.    Nice and fast at F 5.0, a Newtonian so minimal chromatic abberation, nice spiky stars  and  -  with with the 0.9X SW coma corrector (or the Baader one) - not too much coma.  What is not to like?

best wishes
TimH