Consider this a trial run for Mars’s opposition next week. I had not imaged everyone’s favorite red planet since its last opposition ~18 months ago. Fortunately, everything still seemed in order, including the planet itself. Telescope, camera, and all supporting equipment worked as intended. I used my documented ISO and exposure settings from 2018. Judging from the result, they worked well, and should be sufficient for Mars over the next week or so.
Mars is extraordinarily difficult to focus, at least from my Dobsonian. For comparison, Jupiter is relatively easy, as all I need to do is crank up the ISO and exposure, then fine focus until I have sharp dots for the smallest of the Galilean moons. Saturn doesn’t have this benefit, though its unique shape, with the gaps between the rings and planet, offer a serviceable guide.
There are no guideposts when focusing on the Martian disc, which is either near circular or oval. Its two moons are far too small to be picked up by a backyard telescope. So my focus on Mars is always going to be about as “best guess” as guesses go. It’s also why I continually refocus and take at least three to four separate sets of videos.
Summary of my equipment, settings, and software used:
- Telescope: Dobsonian reflector 254mm / 10″ (homemade)
- Camera: Canon EOS Rebel SL3
- Barlow: TeleVue Powermate x5 1.25″
- Filter: Baader Neodymium 1.25″
- Canon T ring and adapter
- Relevant camera settings:
- ISO 800
- Exposure: 200
- HD video at 60fps
- Created from three videos of about 25s each, best 25-35% of frames
- Software for post-processing:
- Registax 6
- PaintShop Pro for minor touch-ups