Baader filters

[Fieldsy]

Hi  imaging going well ish so far .

currently imaging 120 subs was going well but noticed the stars got a little elongated when filter changed s-h    (RMS error 1.5-2.2)normal for me  . I’ve never noticed before but shouldn’t the filters have the same focal point?.

thanks Si

[MarkAR]

All glass is a little different. Baader's are par focal but that just means they are really close but there is still a slight difference in focus. Autofocus steps are incredibly fine so where 100 steps might seem a lot it's only a gnats whisker.

 

[Fieldsy]

9 minutes ago, MarkAR said:

All glass is a little different. Baader's are par focal but that just means they are really close but there is still a slight difference in focus. Autofocus steps are incredibly fine so where 100 steps might seem a lot it's only a gnats whisker.

 

Have just checked and focus seems fine with mask so I’ve reduced down to 90 sec subs and after 20 mins it’s still looking good  ,so maybe it was more mount tracking rather than filters ? .

120 sec subs maybe be pushing Eq5 to its max ,shame as the difference in 120-90 subs was very noticeable.

[MarkAR]

Oh yes, forgot to mention elongated stars is tracking.