Star Adventurer Guiding Issue with PHD2.

[Paul1956]

 

I have a Star Adventurer  with ZWO  guide scope 120mm focal length with ZWO 120mm Mono Camera attached to Canon 7Dmk2 hot shoe securely fitted. I Use a Polemaster for perfect polar alignment.  My lens is a Tamron 150-600mm telephoto. I use Backyard EOS for image control and PHD2 (latest multi star version). Images are near perfect but my question relates to the Declination graph and Star Mass screen in PHD2. Now I am configuring everything correctly with PHD2 set for RA guiding only Declination disabled. What I am seeing is drift in the Declination axis and want to understand what is actually happening and basically can I just ignore this effect as not having any issue with the end image. The Red Declination line will drift upwards on the screen and eventually disappear leaving only the blue  RA tracking line visible (usually tracking +/- 3 arc seconds) and on the star mass green cross lines the guide star drift (usually to the right) over a short period. In the RA axis everything is fine and as I said the end images even at 300 second exposures are perfect. The camera is secure to the declination bracket on the Star Adventurer and balance is great in all 360 degrees positions. Although not worried as such I would appreciate some insight as to what is happening so I can understand. By the way to assist with orientating, my camera is usually fitted to a vertical position, thus on the star mass cross lines RA is Up/Down and Declination is left right...just for ease of interpretation. Thanks Paul

[michael8554]

Hi Paul

Some contradictions here.

If your PA was "perfect" then Dec wouldn't be drifting out of sight ?

It's best when looking at problems to be specific, so better to quote PA error in arcmins, rather than "perfect".

Again "perfect" 300 second exposure images at 600mm FL probably means that your +/-3arcsec RA was matched by a similar Dec error.

Yielding round but bloated stars.

A guidescope and camera on a DSLR hot shoe ?

In theory that is not "securely fitted".

But I should follow my own suggestion and ask you to post a sub, and the PHD2 GuideLog, rather than making guesses !

Michael

 

[trailer]

If you have the DEC turned off then I really don’t think that you have anything to worry about. I also have the SA2i guiding with PHD2 and sometimes the red line shows, sometimes it doesn’t. Doesn’t seem to affect the images for me either, as you have mentioned.

[michael8554]

I think that PHD2 will show the Dec error line even with Dec Guiding off, it does in a Guide Assistant run, where both RA and Dec are off.

So I'd be worried about the Dec line "drifting off" - but he doesn't say if it's continuous drift, or just normal movement above and below the line. so who knows ?

If he's happy with +/- 3arcsec guiding, then we can close this one off.

Michael