Woeful star trails but decent guiding....help

[Turbocoo]

HI all recently ive had to throw out far too many subs due to star trails

Due to my terrible skies I bought a 150 quattro to get faster imaging.

However losing up to 30% of subs due to trailing isnt ideal , besides throwing away for the usual reasons.

The following where taken on a belt modded heq5, 60mm guidescope, 150 quattro, asi 533.
 

Guiding was sub 1".

Ive locked everything down well to rule out flexure and balance is good.

Trails dont seem to follow any pattern and occur at random

 

any help much appreciated

 

 

Edited September 15, 2023 by Turbocoo

[Albir phil]

Looking at your image the trails are horizontal and on the brighter stars not sure but I would say it not tracking problem, more optical Maybe someone else may have a answer for you who has more knowledge one this than I🤔

[symmetal]

Both of your images show trailing in RA only, and it is on all the stars, it's just the brighter stars show it up more. You say balance is good, but you actually want the balance to be slightly off in RA so that gravity always keeps the RA drive gears in mesh and it doesn't 'float' between the gear teeth causing the effect you see. So called East heavy balancing. This should show in your guiding though where it's making corrections but the scope isn't moving as the teeth haven't yet meshed.

It's only out around 5 to 10% of the total image duration so have you checked guiding for the whole duration. If guiding is good as you say for the whole duration then it has to be differential flexure between the two scopes. I had a similar effect and it was the guide cam locking ring wasn't fully tight.

You can get a similar effect if you dither and the capture program starts the next image before the dither has completed. PHD2 does notify the capture software when it's settled after a dither but I tell the capture program (SGP) to also wait until there have been no guide corrections more than 0.2 pixels for 5 seconds before starting the next exposure.

Alan

[Albir phil]

1 hour ago, Albir phil said:

Looking at your image the trails are horizontal and on the brighter stars not sure but I would say it not tracking problem, more optical Maybe someone else may have a answer for you who has more knowledge one this than I🤔

Had another look yes as already been said it's on all the stars

[Turbocoo]

Thanks for the replies. Re balance I should have said that I am slightly east heavy 

Alan, yes I do dither, I'll have to check my settings and perhaps program a longer gap between subs.