EQ8 3-star alignment is not very good.

[Star Hunter]

Has anyone with this mount done a 3-star alignment only to have the pointing accuracy way out afterwards? It seems others on the Yahoo Skywatcher EQ8 group are also experiencing this problem.

My EQ8 MELAZ is 5' and MELEL is 4' yet, whenever I slew to an NGC, IC, Messier object or a star, it's no where near the centre of the SXVR M25C CCD working on C14 faststar which has a 2 x 1.5 Deg FOV.

Mirror is locked and scope and CCD all aligned before a PA using the old and tried Eq. drft alignment. The mount's RA tracking BTW, is superb. Ten minute unguided exp. are very real.

I think Synta needs to do a firmware update on this pointing alignment. Crickey, even my Titan 50 and EQ6 point a lot better than this mount.

James

[h0ughy]

try a two star alignment - works much better. Thats what i did - have to put up until they fix that with the next patch

[Star Hunter]

Will give it a go, mate. How much better was it when you did that?

I wonder if Synta knows about this bug?

[h0ughy]

everything i went to was on middle or very close to middle of chip

[Steffen]

Interesting to hear that the EQ8 (with its doubled-up encoders) is affected, too. It is a well-known issue with other SynScan mounts, running certain hand controller software versions (> 3.27 by the look of it). This seems to support the assumption that the issue is with the alignment algorithm, or the resulting model and GOTO routines, of 3-star alignment.

The only thing 3-star alignment does over 2-star alignment is accounting for cone error. Since that can easily be measured and usually corrected independently there is no real need for 3-star alignment IMO. A fix for this problem is long overdue, nevertheless.

Cheers
Steffen.