Dennis
29-08-2009, 03:53 PM
Hello,
Between 11:18pm on 26th August and 1:43am on 27th August I spent a couple of pleasant hours recording Uranus and four of his brighter moons; Ariel (14.4m), Umbriel (15.0m), Titania (13.9m) and Oberon (14.2m).
Using a Tak Mewlon 180mm F12, WO x2.5 Barlow and SBIG ST7 ccd camera, I experimented with sub-frame exposures ranging from 5 secs to 30 secs, trying to establish the optimum exposure to minimise the overwhelming glare from a grossly over-exposed Uranus yet still record the very much fainter moons.
When I later blinked the finished images output from the 5, 10, 15, 20 and 30 sec frame sets, I was astonished to discover a faint star (15.9m) moving through the field as well as some movement of the moons of Uranus, having aligned on Uranus as a reference point. An animation was called for!
Using the 20 sec exposure data set, I aligned, stacked and combined 30 sub frames for Luminance data (Uranus and moons) and 5 sub frames for RGB data (Uranus only) to produce an LRGB final image, which I then finished in CS3 using various Noel Carboni Actions to reduce the bloat of the moons and enhance their appearance.
Using this (heavily processed) final LRGB image, I overlaid the 10, 15, 20 & 30 second frames and then copied and pasted the moons to place them in their recorded position. Note that the raw frames showed much bloating of the moons due to the long focal length (5400mm) and long exposures (10-30 secs) so I just used my eye to place the finished moons from the LRGB image into the centre of the bloated moon in the 10-30 sec frames.
Therefore, each frame that makes up this animation is a composite and not a direct result of just processing the original data. There are “errors” based on brightness and positioning due to the capture technique and post processing involved. But, it sure was fun putting this together!
Thanks for looking!
Dennis
Between 11:18pm on 26th August and 1:43am on 27th August I spent a couple of pleasant hours recording Uranus and four of his brighter moons; Ariel (14.4m), Umbriel (15.0m), Titania (13.9m) and Oberon (14.2m).
Using a Tak Mewlon 180mm F12, WO x2.5 Barlow and SBIG ST7 ccd camera, I experimented with sub-frame exposures ranging from 5 secs to 30 secs, trying to establish the optimum exposure to minimise the overwhelming glare from a grossly over-exposed Uranus yet still record the very much fainter moons.
When I later blinked the finished images output from the 5, 10, 15, 20 and 30 sec frame sets, I was astonished to discover a faint star (15.9m) moving through the field as well as some movement of the moons of Uranus, having aligned on Uranus as a reference point. An animation was called for!
Using the 20 sec exposure data set, I aligned, stacked and combined 30 sub frames for Luminance data (Uranus and moons) and 5 sub frames for RGB data (Uranus only) to produce an LRGB final image, which I then finished in CS3 using various Noel Carboni Actions to reduce the bloat of the moons and enhance their appearance.
Using this (heavily processed) final LRGB image, I overlaid the 10, 15, 20 & 30 second frames and then copied and pasted the moons to place them in their recorded position. Note that the raw frames showed much bloating of the moons due to the long focal length (5400mm) and long exposures (10-30 secs) so I just used my eye to place the finished moons from the LRGB image into the centre of the bloated moon in the 10-30 sec frames.
Therefore, each frame that makes up this animation is a composite and not a direct result of just processing the original data. There are “errors” based on brightness and positioning due to the capture technique and post processing involved. But, it sure was fun putting this together!
Thanks for looking!
Dennis