Ha Filters?

[steppenwolf]

I use the 13Nm Astronomik Ha filter with my SXVF-H9C and it works pretty well - halos? Nah ......

[centroid]

Perhaps the stars are different, as seen from the IoW :?

Dave

[Paxo]

Perhaps the stars are different, as seen from the IoW :?

Dave

Not the stars Dave, just the filters.

Steve

[centroid]

[markcol]

I find it's dependant on the size and brightness of the star in the field, Alnitak is obviously going to be a problem.

I didn't get halos either with the NA Neb, I must refine my technique to minimize it as 'over enthusiastic' stretching makes it worse...

BTW Dave, I've a spare Astronomik 13nm Ha 1.25'' if you want to try it out- PM me soon if you're interested as I'm off 'down under' on next Tuesday week.

(Stars are more or less the same size from I.O.W - just clearer!)

Mark

[centroid]

Hi Mark

Its more a matter of over sharpening that leads to dark halos around stars, rather than stretching. Its an unfortunate consequence of the unharp mask filter.

Isolating the stars into another layer within photshop, before applying unsharp masking, is a good practice, and allows you to sharpen and stretch the rest of the image, with degrading the stars.

MartinB, has written/posted a good tutorial on the way he does it. The are other ways, but Martin's method is quite effective.

Thanks for the kind offer of the filter loan, but I'm in no rush, as I've got so much evaluation work to do, with the now repaired H9C, and the new IDAS filter, and a drastic shortage of clear skies to do it with.

I guess you are off down to NZ to join John (moondog), ableit he is coming back to UK next month.

You'll enjoy the weather down there, much better than here at the moment . and snow!!.

Also, if you've not seen the Southern night sky before, you are in for a real treat.

I'm hoping to be back over in Oz again, later this year.

Enjoy NZ Mark, log onto the forum from down there, and let us know what you are up to.

Have a great trip.

Dave

[markcol]

Many thanks Dave, BTW -what's this snow stuff I keep hearing about?

(A light dusting this morning , now all gone and the sun's out!)

Mark