Hey Greg, You make a fair point on the starry field. SL17 is in a star rich area in the MilkyWay so I don't think there is a way of avoid this, nor would I want to incorrectly portray the area. Stars are there to embrace, not butcher. What I found interesting was your comment that you want to see luminance data, but you don't want to see so many stars. Luminance filtered data is only going to amplify the star field so its rather counter intuitive. I'm also not sure where you got the HaRGB from...this is a [Ha+R]GB, yes there is a difference.
I think if I were to add a luminance to this image, I would use the red filtered data anyway as the stellar profile is tighter. No need to use a textbook clear filtered data as a luminance for neb work. Anyway, thanks for the good feedback. I may pick up some pointers from you with your RH images given you're going to face the same starry challenges. Just remember to embrace, not butcher.
Embracing embracing. I am humming the mantra. Good point though and of course you are right. The stars do need to be respected. I usually find though that the luminance data has the tightest stars. Your stars colours are quite pastel compared to what I go for (personal taste) and perhaps more accurate. David Malin has made that point that he studied star colours and wrote a book about it and that they are in fact pastel shades.
Your setup and mine are relatively similar so yes we do face similar image challenges. The RHA tends to blow out the bright stars quickly so I am thinking either even shorter subs to compensate or handle in post processing. What sub lengths do you use? Your bright stars seem fine but your average star sizes are a little large compared to the Honders (its also shorter focal length 1159mm). Perhaps that is merely the focal length - nearly 1400mm. I noticed my TEC180FL at 1260mm gave largish stars (with 9 micron pixels) whereas the AP140 (1050mm focal length) gave very tight stars. The CDK17 gives quite tight stars under good seeing (although broader with the Trius 694). I predict your 16070 camera will give better stars because of the deeper wells. You may need to fine tune your tilt or spacings a tad as I suspect they are not quite there. The 16070 from images I have seen is a strong performer and I look forward to your 16070 images. Its a sensor I am considering at some point.
The Honders is particularly fussy to tilt and perhaps that is true of any F3.8 type scope. Also I imagine tolerances for spacing from the corrector and are even more fussy at F3.44 (1396 focal length divided by 406.4mm aperture).
Greg.
Thanks Ian!
I do have a star reduction tool for PS. I use it sparingly now and then. I find it can mess with the relationship between large and small stars which distorts the presentation. Something I wish to avoid. Thanks for checking it out.[/QUOTE]