Patrick, You are dead on about the focal length and the star size. My dad uses a C-14 for his imaging, and we have had many discussions on this topic. In my opinion, the star size is usually dictated by the atmospheric conditions more than the optics. With the jet stream passing over our heads (as it usually does), our skies are pretty shaky. Those little wobbles don't amount to much when shooting at 520mm with my Tak Epsilon or at 720mm with the ASA N8, but are pretty obvious when shooting at the focal lengths you use (I'm guessing your C-14 at F/11 is roughly 3073mm). In almost every case, if you shrink the size of your image down to the same scale as mine, the star sizes will look about the same. Cheers, Tyler _____________________________________________ -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Thursday, February 26, 2009 2:01 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] HH from Patrick's data Very nice Joe, Tyler sent me his version after what he called "a relatively quick processing job" and while his colors are a bit different from your version the overall sharpness and appearance is quite similar to yours. You have come a long way with your processing skills. Now if you'd just get your observatory built so you could start taking more data of your own... (that was an unsubtle hint, BTW.) Joe, as I've long suspected, one of the reasons Tyler gets such small, pinpoint-like stars is he is using a much shorter focal length than you or I. I came to this conclusion by taking his version of my latest Horsehead and shrinking it down to the same size as Tyler's jaw dropping shot of the HH and surrounding region. I then placed it next to Tyler's original and got a pretty good match. Still not quite as good as his, but pretty darn close. http://users.wirelessbeehive.com/~paw/temp/hhcomp.jpg patrick On 25 Feb 2009, at 18:46, Joe Bauman wrote:
Here's my slapdash effort to assemble Patrick's data -- obviously I didn't pick out some of the bad pixels:
http://www.slas.us/gallery2/main.php?g2_itemId=1141
I didn't use flats because it seems fine without them. -- jb
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