SkyWatcher Az Eq6 - Help

[Uriabraham (Uri)]

Hi all,

I have recently purchased the SkyWatcher Az Eq6, a nice progress from my old CG-5. Was very happy at first days of use but later I have discovered some issues...

1. There is a free paly in the RA axis; can be easily noticed when gently nudging the counterweight bar
2. DEC backlash appeared out of nowhere. My PHD calibration process was initially showing 'Clearing DEC backlash' and was going for 2 steps, now it goes up to 10 !.

I didn't find many resources about issues with this mount so I would appreciate discussing these issues and possibly other regarding this specific mount. Hopefully some users here have more experience mine

Any help much appreciated

Thanks
Uri

[Amaranthus (Barry)]

The play in RA is expected - you do not want the mesh with the worm to be too tight. The backlash is minimal in practice, thanks to the belt drive. My AZ-EQ6 can produce round stars in 30 min subs using PHD2.

[killswitch (Edison)]

Most AZ-EQ6's seem to come with a bit of RA play. You can reduce it by following the astrobaby eq6 worm adjustment guide

[Uriabraham (Uri)]

Thanks you Barry and Edison.

What average DEC/RA amplitude in arc seconds can I expect to get from this mount. I get around RA 0.7 arc seconds and DEC 0.4 arc seconds. Is this reasonable ?, Barry, you are taking 30 Min exposures, with no trails ? wow that's very long, nice.

Edison I will read follow that link, thanks

Ty
Uri

[Amaranthus (Barry)]

It depends on the image scale, of course. My 30 minute subs were at about 3 arcsec/pixel, with the amplitude for that setup (a SW120 with an ASI120MM on an OAG) being consistently <1 arcsec/px.

I haven't tried that long (yet) with my C8 which will give me about 1/px image scale, but that's only because I only relatively recently got the OAG - not for any fear that it might not work. I've heard that if you mesh the worm too tightly, it can cause real problems. The slight 'slop' is there for a reason, and if the play is not too large and not causing guiding problems, I would not worry

[Uriabraham (Uri)]

Barry,

Thanks for shading more light on this.

I have the Orion mini auto guider with 6.5 arc seconds per pixel. Is it correct to assume that an auto guider with a longer focal length is more sensitive therefore PHD will make better corrections and as a result better guiding ?, or is it also how you setup the various PHD parameters ?

Bye the way, the periodic error i'm getting peak at about 1.5 arc second !

I'm attaching a screen shot of PHD, if you have time, please have a quick look and tell me if the parameters are setup reasonably

Thanks heaps for your help
Uri

[Amaranthus (Barry)]

Yes, a longer FL guidescope or and OAG would improve things, but the choice of image scale for your guiding depends a lot on your imaging pixel scale. There does seem to be some residual PE in the RA curve. I don't see a response like that in my setup. Have you tried AutoPEC (via EQMOD)? What do your long-exposure stars look like?

[Uriabraham (Uri)]

Barry,

These are the details of my imaging gear;

Scope Aperture:120mm
Scope Focal lenght:7.5
Camera Pixel Size:4.31 micron
Pixel array: 5184x5346
calculated Resolution:0.99 arc seconds/pixel

I haven't taken a exposure longer than 5 min. going to try one day soon (waiting for weather to improve) and no star trails and pretty round

No, I haven't tried any other guiding software, Do you recommend ?

Perhaps I need to play with the PHD settings (more aggressive ?, hysteresis ?) to minimize the PE as you mention above 'residual PE'

Thank you Barry for your kind help
Uri