tommy_h Posted December 17, 2013 Report Share Posted December 17, 2013 Hi Here's an 2-panel mosaic of NGC 7331 and Stephan's Quintet. Taken with the 10" Astrograph and the ASA 2" 1.8 Barlow-Corrector (focal length 1620mm, f/6.8) Each panel 10h exposure time in 15min subs with a Canon 500D Mount was a DDM60, unguided Mount controlling and image acquisition automatically with Sequence Beta (works perfectly) Higher resolution: http://www.distant-lights.at/ngc7331-2013_09_09.htm Thomas Link to comment Share on other sites More sharing options...
markusblauensteiner Posted December 19, 2013 Report Share Posted December 19, 2013 Again perfect Thomas, the cirrus is clearly visible and details are great! BR, markus Link to comment Share on other sites More sharing options...
MartinN Posted December 22, 2013 Report Share Posted December 22, 2013 Hello Thomas, it is amazing, how much fine details are visible within Stepahn's Quintet. The resolution of the whole image field seems very good. This is astonishing, considering the subexposure lengths of 15min. Can you give statement, which FWHM in pixels the nonsaturated stars (such with maybe 2000 or 1500 counts of pixel value) have in these subframes ? What is the FWHM shown in Fitswork, for example ? I am thinking about moving to a single telescope solution for both astrograph use (F/3) and long focal length photography (F/6.8). That's why I ask such questions... Kind regards, Martin Link to comment Share on other sites More sharing options...
tommy_h Posted December 22, 2013 Author Report Share Posted December 22, 2013 Hi Markus and Martin Thank you for your comments! Martin: the conditions during image acquisition were bad. I have measured several subs from different nights in Fitswork. the best FWHM is 4.6 px, the worst 6.8 px Regards Thomas Link to comment Share on other sites More sharing options...
MartinN Posted December 24, 2013 Report Share Posted December 24, 2013 Thomas, these FWHMs of 4.6 to 6.8 px are not that bad, in my opinion. Considering the px size of 4,7µm, FWHMs equal to (linear) 21.6 to 32 µm, which are below 2.8" to 4.1" at 1620mm focal length after a single 15 min exposure. Furthermore, the good value is well below the specification in matrix spot diagrams of the 2" Barlow Corrector at the 250mm f3.8, available at ASAs website. The smallest FWHMs I got with 5min exposures were 2.8" with 5,12µm px size (at 1860mm focal length), when seeing was among the best low values of the year (I will post the image here after processing). Still an argument FOR this long focal length instrument. But the easier focal length selection anytime by using the appropriate corrector at an f3.8 or f4 mirror telescope is a clear advantage, balancing out the comparable resolution of an extra instrument (requiring a complete exchange of the telescope, maybe even at night). Kind regards Martin Link to comment Share on other sites More sharing options...
afesan Posted December 24, 2013 Report Share Posted December 24, 2013 WIth the imaging conditions described the image is much more meritory. Very nice colours and details, even at 4-6 px FWHM. Inverted version permits appreciate delicate details into the colour one. Nice job, Thomas. Congratulations. Antonio Link to comment Share on other sites More sharing options...
tommy_h Posted December 26, 2013 Author Report Share Posted December 26, 2013 Thank you, Antonio Thomas Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now