High res "EEA" with SC autostacks + Blur Xt
Posted: Sun May 12, 2024 10:45 am
Whether the below really counts as EEA I am not quite sure -- but it does seem extraordinary that technology has advanced so rapidly over these past few years that it is now possible to observe four or more objects - in this case local galaxies - in really very high detail from a Bortle 7 back garden in the course of a single night.
The set up was as follows ....
Orion Optics (UK) VX12 F4 Newtonian, SW aplanatic coma corrector, CEM 70 mount
ASI294 MM mono camera
Camera set at 46 Mb - pixel size 2.315 u - to capture 10s short frames at gain 200
Image scale 0.406 arcsec/ pixel
The VX12 was accurately collimated with a Howie Glatter laser and tublug -- in fact the final images were surprisingly sharp after BlurXt star correction and deconvolution even when the collimation was consistent but slightly out. But unsurprisingly - the very best final images were obtained when collimation was spot on.
The above 10s gain 200 camera setting at 0.406 image scale about hits the sweet spot for semi 'lucky' imaging with a 12 inch telescope at F4 under my B7 moonless dark. Under dark skies could go for shorter frames to possibly improve resolution but - SNR is just as important. In order for RC BlurXt deconvolution software to work optimally not only is SNR important but also sampling - so 0.406 provides a better potential for final resolution than does the alternative 4.63 u pixel (0.81 image scale) setting available on the camera (although the 4.63 setting provides better SNR - so everything is a compromise).
Sharpcap capture is set up for autostacking (up to 60 min), and filtered to reject frames with low brightness and/or with an FWHM > ca. 6 pixels (FWHM ca. 2.4 arcsec).
EEA is of course ongoing as you watch the image of each object build up until the point that the autostack is saved and then move on to the next target.
The variation here on the usual EEA procedure is simply to have a second computer available running PixInsight with the RC Blur Exterminator software. The additional processing then just takes about 2-3 minutes in exchange for an enormous increase in image quality. Simply upload the Sharpcap autostack and 1) apply star correction and then 2) Blur Xt deconvolution (usually settings ca. 0.4-0.6 non-stellar - zero star reduction)
The improvement from deconvolution seems almost like magic but comparison with HST NASA/ ESA images convinces me that the process is not introducing noticeable artifacts. Generally the better (scope well collimated skies not too turbulent) integrated autostack images are starting out at an FWHM estimate of ca. 2 , Eccentricity ca. 0.5 -0.6 and apparently ending up at about 1.1 and < 0.4 after deconvolution.
The quality of these obviously varies - sometimes conditions were better and worse. I have a more full details and analysis on quality of captured frames etc should folk want them -- in addition the more conventionally processed images but I thought it interesting just how good the images were just direct from the EEA Sharpcap autostacks
Tim
The set up was as follows ....
Orion Optics (UK) VX12 F4 Newtonian, SW aplanatic coma corrector, CEM 70 mount
ASI294 MM mono camera
Camera set at 46 Mb - pixel size 2.315 u - to capture 10s short frames at gain 200
Image scale 0.406 arcsec/ pixel
The VX12 was accurately collimated with a Howie Glatter laser and tublug -- in fact the final images were surprisingly sharp after BlurXt star correction and deconvolution even when the collimation was consistent but slightly out. But unsurprisingly - the very best final images were obtained when collimation was spot on.
The above 10s gain 200 camera setting at 0.406 image scale about hits the sweet spot for semi 'lucky' imaging with a 12 inch telescope at F4 under my B7 moonless dark. Under dark skies could go for shorter frames to possibly improve resolution but - SNR is just as important. In order for RC BlurXt deconvolution software to work optimally not only is SNR important but also sampling - so 0.406 provides a better potential for final resolution than does the alternative 4.63 u pixel (0.81 image scale) setting available on the camera (although the 4.63 setting provides better SNR - so everything is a compromise).
Sharpcap capture is set up for autostacking (up to 60 min), and filtered to reject frames with low brightness and/or with an FWHM > ca. 6 pixels (FWHM ca. 2.4 arcsec).
EEA is of course ongoing as you watch the image of each object build up until the point that the autostack is saved and then move on to the next target.
The variation here on the usual EEA procedure is simply to have a second computer available running PixInsight with the RC Blur Exterminator software. The additional processing then just takes about 2-3 minutes in exchange for an enormous increase in image quality. Simply upload the Sharpcap autostack and 1) apply star correction and then 2) Blur Xt deconvolution (usually settings ca. 0.4-0.6 non-stellar - zero star reduction)
The improvement from deconvolution seems almost like magic but comparison with HST NASA/ ESA images convinces me that the process is not introducing noticeable artifacts. Generally the better (scope well collimated skies not too turbulent) integrated autostack images are starting out at an FWHM estimate of ca. 2 , Eccentricity ca. 0.5 -0.6 and apparently ending up at about 1.1 and < 0.4 after deconvolution.
The quality of these obviously varies - sometimes conditions were better and worse. I have a more full details and analysis on quality of captured frames etc should folk want them -- in addition the more conventionally processed images but I thought it interesting just how good the images were just direct from the EEA Sharpcap autostacks
Tim