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Hello All again, Sharing with you the other image I've taken of the Rho Ophiuchus/Scorpio region, two nights later. This was taken with a Canon 40D DSLR and a 50mm Sigma lens. Total integration time was 2 hours with 30, 60 and 120 second ISO800 subs. Clear Skies. MG
For deep sky observers and astrophotographers it simply is the stuff of dreams. In late April on an early morning imaging run I exposed the wonderful region of Sagittarius and southern Ophiuchus for what was my first good imaging session of the year. As many of you know, I still buck the trend of digital capture and prefer analog methods. I continue to produce wide-field images like this, perhaps as a reminder of how things were done in the glory days of film astrophotography (they truly were) when very few were doing serious work. Today there is an explosion in the population of astrophotographers, thanks to modern equipment. I am pleased to share this image, captured the old fashioned way. It was captured under the dark skies of my home in Maine, USA. An old Pentax 67 with a 165mm f/2.8 portrait lens set at f/4.8 and exposing Kodak Ektachrome 200 for 35 minutes using my Meade 2080 as the guiding platform. The Kodak transparency was push processed to gain effective speed and allow faint details to be rendered in brighter tones. The dynamic range of this film is phenomenal and proves that reciprocity failure, the cop out of many imagers to go digital, is a myth. To be fair, it is digital technology that allows this image to be processed to reveal just what it has stored in those thin layers of emulsion. When the film is gone, so are these images. They will be relegated to the ash heap of history. I hope you enjoy the image, a glimpse of a time gone by and surviving by a thread, in my freezer right next to the frozen peas.
It's been a such a long time since my last session, I thought I may have forgotten what end of my scope I was meant to look through. Thankfully it all came flooding back. The sky was not great to start with and I was in a hurry before the Moon lit the sky up. I started with a return to M57, the Ring nebula. Easy to find without maps and a rewarding view. At 42x magnification, the hole was quite clear and at 80x the ellipse became more obvious. I would definately rate it as a top 20 object for beginners as it is tolerant of light pollution. I then turned my attention to the East side of Ophiuchus and two globular clusters. Just to the Northeast of Nu Ophiuchi and almost in line with the fifth magnitude Tau Ophiuchi is NGC 6517, a small 10th magnitude glob with a supposedly high surface brightness. Unfortunately the quality of the sky at that elevation resulted in an inconclusive attempt. A little further Northeast, beyond Tau Ophiuchi, is NGC 6539. This larger and slightly brighter cluster was just about possible but was nothing more than an averted vision dirty mark. The final object I viewed was the small planetary nebula NGC 6891, in Delphinus. It appears as one end of a V-shaped asterism of stars between magnitude 8 and 10 to the West of the famous diamond head of the dolphin. With maximum magnification of 126x it could just about be identified as slightly less stellar that the nearby stars and possibly slightly elliptical. My scope struggles a little with sharpness at that magnification. A longer focal length would go a long way with this one as its surface brightness is such that it could take substantially more magnification. It's good to be back and a couple of new finds in a short session was satisfying. __________________________________________________ ______ Observing Session: Wednesday 5th September 2012, 21:20 hrs to 22:15 hrs BST VLM at Zenith: 4.9 - 5.0 New - Revisited - Failed