photo stacks — BLOG

CELESTIAL CONFINEMENT

6ème Kilomètre, Noumea

Day 20 of auto-confinement announces an extra week of… confinement.

My failure to capture the Super-moon this week pushed me to try my hand at capturing the South Celestial Pole. Though the conditions weren’t the best (the full moon), the opportunity was, with clear skies and the terrace facing south/west. I don’t think it’s too bad for my first attempt, what do you think?

The South Celestial Pole is difficult to explain. It’s an imaginary point in the sky that shows the rotational axis of the Earth. It’s a point in the sky where stars seem to rotate in a circle but in fact it’s the Earth rotating. The South Celestial Pole is only visible from the Southern Hemisphere and the North Celestial Pole only from the Northern Hemisphere.

535 images | 28 mm, 30 seconds @ ƒ/8, ISO 400Sony a7 III + Tamron E 28-75 mm ƒ/2.8 Di III RXD

The idea was to capture the South Celestial Pole through multiple long exposures. Then stack them using StarStax (or any other software that can do the same job) to produce a single image. I would need a few hundred photos for the effect wanted so, apart from a camera and lens, I would need a tripod and an intervalometer. Even though I have a wired remote shutter release, I used the Sony a7 III’s in-body intervalometer for this project. I ended up shooting for about five and half hours but that’s because I miscalculated the total duration time of the project. I based my calculations just on the intervalometer which gave me an hour and half total duration time (1800 exposures x 3 second intervals or pauses between exposures). My mistake was not realising that the intervalometer wasn’t taking into consideration the exposure time of 30 seconds for each of the 1800 exposures, which gives me fifteen hours of just exposure time. Yep, off by that much. I used the PhotoPills app to find the South Celestial Pole but unfortunately, the calibration was slightly off and thus the pole isn’t centred above the flame, as I’d intended. No matter, now I know and will give it a go another time.

I started shooting around 11:30 pm and stopped round 5 am, which gave me about 600 photos. I didn’t use all of them as a few in the beginning and end had too many clouds and a handful in the middle had moved when I stepped out onto the terrace at 1 am thinking it was all finished. It’s also when I thought about why my calculation was off. I ended up using 535 photos for this image. I edited the first one in Lightroom then synched the edit to all the images. I exported them to a folder on my desktop then imported them into the StarStax application. Oh, I forgot to mention that I took a dark frame at the end of the shoot. That is, the exact same exposure as the other 600 but with the lens cap on, to capture a dark image. I also imported this frame into StarStax. It helps with noise and other stuff. Astro-photographers say you should also take bias frames but I didn’t bother. I mean, I almost forgot about the dark frame let alone the bias ones. Anyway, once the 535 photos and dark frame imported, I just clicked on process and left the application do it’s thing. The stacked image shown wasn’t great, to tell you the truth. So I reprocessed the 535 photos multiple times with different settings/configurations but the stacked image was never… it never seemed quite finished. It wasn’t the results I was hoping for. Until I decided to go ahead and export one of the stacked images and saw it was just fine, great even. The application must do a final rendering as it exports the final stacked image because the difference is day and night. Happy with the image, I brought it back into Lightroom for a final edit then into Photoshop for a bit of cleaning and added the flame on the torch. I couldn’t let the torch burn all night so decided to photoshop it in instead. Not the best work but it does the trick, no?

I hope I’ve explained myself clearly enough for you to understand how I came away with this image. If not, let me give you a simpler explanation. I took lots of photos of the exact same scene/picture. Now the foreground (terrace, buildings and trees) don’t move but the stars do, they rotate in the sky. So once I stacked all the photos on top of each other, because the foreground (terrace, buildings and trees) hasn’t moved, it stays exactly the same in the final image. The stars though have moved/rotated during the night, so once stacked, it shows the path they’ve travelled during the night, hence the circles in the final image.

I hope that has helped a little and I hope you’ve enjoyed this post. Talk to you soon and don’t forget, if your area is in auto-confinement, please stay home and if not or you’re working, please protect yourself and others by implementing the protective measures. Stay safe.