16
APR
2020

Back under the stars

With the whole world battling through the coronavirus pandemic, most nations are in lockdown mode. If you’re reading this now, maybe you’ve found yourself with some free time on your hands. Time to do things other than work. More time to indulge in old pastimes. More time to go outside and see a brilliant clear sky, free from contrails. And even more time to write rambling blogs about the experience! After 4 years without a peep, the lockdown has finally provided me with an opportunity to rekindle my love affair with the night sky.

Revisiting my old hobby was always in the back of my mind. Every clear moonless night that passed by would give me a slight feeling of guilt. Not only that I was missing an opportunity, but also that I’d let this blog go unloved for so long.

But times and technology have moved on since I started to document my exploits with the home-made barn door tracker. Star trackers have become much less expensive, more portable and more accurate. Around a year ago I managed to pick up a used AstroTrac TT320X-AG for a bargain price. Along with a new Nikon D5500 camera, and several other new lenses.

My very first target back in August 2013 was the Great Clobular Cluster in Hercules. I remember being blown away by the results at the time. But looking back 7 years later, it doesn’t seem quite as impressive! I felt there was no better target for the ‘first light’ of my new setup than M13.

Polar alignment was quick and painless thanks to a laser pointer adaptation I made to the tracker (replacing the original polarscope). Below is the final 10 minute stacked image of 20 x 30 second exposures…

Details: Nikon D5500Tamron-100-400mm-f4.5-6.3 @ 400mm/f8. Total of 10 minutes exposure time (20 x 30 seconds) at iso 800. Stacked with Deep Sky Stacker and tracked with AstroTrac TT320X-AG

M13 comparison The result speaks for itself.. This direct comparison shows the difference between my previous best efforts with the old setup using the ban door tracker, Nikon D7000 and 180mm f/2.8 lens.

Upgrades in all areas combine to give results far beyond what was capable before. The difference is like night and day. The AstroTrac is far more consistent with it’s tracking than I could ever achieve with the barn door tracker. And with far less hassle!

The new camera’s modern 24mp sensor also gives a healthy 50% jump in resolution over the 16mp D7000. It also does away with an anti-aliasing filter which boosts sharpness further still. Finally the Tamron lens is extremely sharp at 400mm, giving far longer reach than my trusty old 180mm Nikkor. I’m eager to test it out on new targets, while improving existing images too.

  1. Mike Reply

    Great to see you’re back imaging, love your thrifty approach to everything!

    • Nick Reply

      Thanks Mike. It feels good to be back. And I do love a bargain! 🙂 – Nick

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