November 8th, 2021, 5:11 p.m. local time
Continuing the daily series this week of evening astrophotography sessions, tonight I focused completely on the Moon. It was about as far East of Venus as it was West yesterday, maybe slightly further. I took pictures only of the Moon because I brought out the big gun, my 254mm Dobsonian. While the Moon has been gradually rising each night, it is still relatively low after Sunset, due to the season, and only keeps descending towards the Southwest horizon afterward. Given the position of my telescope on my back deck, it was impossible to aim even lower and West for Venus. The telescope was positioned so low, I sat comfortably at the eyepiece with a patio chair, an extremely rare posture when using my Dobsonian.
I took the above photograph “afocally,” meaning I used a camera positioned literally right up against the telescope’s eyepiece. In this case, the camera was my iPhone. I used NightCap to take about 45 photos, and this was roughly the best.
A nice advantage of this afocal method is that it is way easier to focus, unlike the problems I had the night before with the digital camera on tripod. The Moon is large through a 2-inch eyepiece. I played with the focus and when I was satisfied with the sharpness, locked the focuser in place before attaching the iPhone.
Interestingly, when I increased the exposure on a few images, I found what appeared to be a star above the Moon (actually below at the eyepiece since Newtonian reflectors flip the image). Here is what an over-exposed Moon looks like, in order to show the star:
The star was not yet visible to the naked eye within 30 minutes after Sunset. I guessed indeed that this dot was a star and not a planet, like Mars, for example. Later, I pulled up Stellarium to confirm it was a star, named Nunki, the second-brightest star in the constellation Sagittarius.
Stellarium, or any star chart software, is great for confirming relative positions of objects seen at the telescope or through binoculars.
Telescope and photography settings for the solo Moon photograph:
- 254mm Dobsonian (homemade)
- 1/250 sec exposure
- ISO 50
- Q70 32mm eyepiece (2.00″)
- iPhone XS with NightCap app on eyepiece mount
- Touchups in PaintShop Pro and AfterShot Pro
