First attempt at imaging the Andromeda galaxy with the new Nikkor 180mm f2.8 ED Ai-s lens. I was able to grab just 2.5 minutes of exposure time before the clouds rolled in, but the resulting image stacked in Deep Sky Stacker blew me away!
The lens is incredible. It can be shot wide open at f2.8 while still producing sharp contrasty images, with very little coma. There is more detail visible in a single 30 second exposure with this lens, than a full 5 minute exposure with the 18-105mm. The spiral arms and dust lanes stand out nicely in the final image, with the two satellite galaxies M32 and M110 easily visible. The colour the lens produces is another welcome improvement over the flat colours from the old lens, and something I hadn’t expected.
This sequence shows the progression over the last 2 months, from single 10 second image, to the most recent tracked and stacked image. All images were taken with the Nikon D7000 at iso 1600:
- View – Single frame with Nikkor 50mm f1.8, on fixed tripod. 10 second exposure at f2.5.
- View – 30 frames with Nikkor 50mm f1.8, on fixed tripod, stacked with DSS. 5 minute exposure (30 x 10 seconds) at f2.5.
- View – 3 frames with Nikkor 18-105mm f3.5-5.6, tracked with barn door tracker and stacked with DSS. 5 minute exposure (3 x 100 seconds) at f5.6.
- View – 5 frames with Nikkor 180mm f2.8 ED Ai-s, tracked with barn door tracker and stacked with DSS. 2.5 minute exposure (5 x 30 seconds) at f2.8.
The key to improvement was building the barn door tracker which allowed for longer exposures, along with Deep Sky Stacker to reduce noise and bring out the details. I should be able to improve on the sequence even further once the weather picks up!
After 3 weeks of bad weather and moonlight, I eventually had another go at the Andromeda galaxy. The final image (below) is a definite improvement as the galaxy was near zenith at time of shooting, so there was less atmosphere in the way. At 6 minutes and 30 seconds (13 x 30 seconds) it’s also a longer exposure. I think it would be possible to improve still further, but I’d need to go to a dark sky site and use ‘sub frame’ exposure times longer than 30 seconds.