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Good step forward Lewis, looks like the sensitivity is there. However, the stars are huge for 6nm Ha, as they were with your colour image. There is a pair of stars just outside of the main nebula at about 2 o'clock that should be well separated (see other Helix images on IIS) - the stars are merged in your image. Suggest that in Pixinsight, click on a few unsaturated stars in "dynamic PSF" and see what it reports as the FWHM.
Unless you had extremely bad seeing, first guess is that the focus is out - what procedure do you use and do you refocus as the temperature changes?
Second possibility is mount tracking noise - do you get tighter stars with very short exposures on bright stars.
Third possibility is an optics fault. If this image was taken with a focal reducer - is the spacing as specified. I would check without a focal reducer first off and would also try some other scope (an ED80 or even an achro if you have one) and see if you can get tighter Ha stars. Also, do a star test to see if the main scope has acceptable spherical aberration. If your main scope is faulty, the only real option is to get it factory refurbished - unless you are extermely lucky, all you could expect from trying to adjust a multielement refractor without alignment equipment would be to make it worse.
Cheers ray
Last edited by Shiraz; 12-10-2013 at 10:06 AM.
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