It’s been a few days of cloudy nights so I took the time to trawl the internet and use Stellarium on my PC to locate the next target to photograph. I came across a few photos of the Rho Ophiuchi complex and they looked stunning, figured I’d give it a go.
My setup consists of my Olympus OMD Em5 Mark II with a Canon FD 70-210mm lens attached. At 210mm the field of view is equivalent to 420mm on a full frame camera and the framing of the target is just perfect. My Star Adventurer tracker is mounted on my manfrotto tripod, and at the bottom of the stabiliser arm I have a ZWO Mini Guidescope mounted and a ZWO 120mm-s mono guide camera attached to it. The ZWO and Olympus cameras are attached to my laptop for control and the ZWO camera also attaches to my mount via an ST4 connection.
This entire setup allows me to get perfect alignment to the south celestial pole here in Australia, the point where the stars appear to rotate around, using the ZWO camera and Sharpcap software. Once polar aligned the ZWO then turns it duties to guiding where it will monitor a star for movement, and nudge the mount east or west while it rotates, giving me much longer exposure times. Here is a photo of the simple setup in my backyard.
The Rho Ophiuchi Complex (don’t ask me to pronounce that btw lol) is easy to find by locating the bright orange colours star Antares as it rises in the east, at around 8.30pm at the moment. I waited until around 10pm to actually start photographing it to avoid as much light pollution from the coast as possible, however the effect of it was still quite strong. Below is a wide view from Stellarium of what to look for.
The complex from my point of view is based to the east of Antares so I framed up the shot with Antares towards the lower right which brought the rest of the stars into good framing. This complex has an array of dust and colours, looking closely in Stellarium you can see what I’m talking about :
I would have liked to be in a true dark site to photograph this and avoid the noise pollution. I also had to contend with a rising moon after around an hour into the shoot so conditions were not really ideal. Finally, my camera is unmodified so the reds from around the top star, while there, are greatly reduced due to the standard filters over the sensor blocking the red H-Alpha colour. I definitely have to look at a modified camera soon and special filters to block light pollution.
All up I took 40 images at 3 minutes long each, ISO 400 and F5.6 on the lens. I always stop this lens down a bit to reduce it’s chromatic aberration (purple and blue fringes around the stars) as it’s an old lens and not perfect. Then I took 10 dark frames (same exposure settings but with lens cap on) which are used to remove noise and hot pixels, 29 Bias frames, shot at 1/8000 of a sec (cameras fastest shutter speed) to help remove sensor read noise, and 29 flat frames (auto exposure, white t-shirt over the lens and an even light shining on the lens) which are used to reduce vignette from the photos. All of these are put together in Deepskystacker to create a final combined photograph.
I then spent quite a bit of time in photoshop bringing out the details, reducing the light pollution and correcting colours. This is the final result, and you can download a Free copy by clicking here for your wallpaper if you wish.
I had a lot of fun photographing this target. I setup our tent and camped in the backyard with my daughter. We played cards, had lots of snacks and hotdogs while the camera and gear went on it’s merry way capturing the images. Not a bad way to spend some isolation time. I hope everyone remains safe and healthy, until next time, clear skies 🙂