A few days ago, I got to try for the first time my new lens, the Canon 300mm f/4L USM, which has the perfect focal length for the Andromeda Galaxy (Messier 31). I believe there might even be some room left for a 1.4x extender, while having M31 fill the whole frame! But that’s for another night :-)
The acquisition
Unfortunately, my iOptron SkyGuider Pro mount had an internal issue, and the right ascension axis was quite wobbly. It was difficult to maintain the lens and the counterweight in a steady position, and I was afraid that the final result would be terrible.
Eventually, I opted for a rather short exposure time, 45 seconds, and started imaging my target. The seeing was rather good, from a Bortle 3/4 location south of Munich.
Mount: iOptron SkyGuider Pro (with counterweight)
Camera: Fujifilm X-T1
Lens: Canon 300mm f/4L USM
Aperture: f/4
ISO: 1600
Lights: 95 x 45 seconds
Darks: 41
Flats: no
Bias: yes
Post-processing: DeepSkyStacker, Photoshop
The result
I’m very happy with the result! Until now, I only had a shot at Andromeda with my Samyang 135mm, which is more forgiving when the polar alignment isn’t perfect. But it also requires quite a lot of cropping.
At 300mm, M31 fills about 1/3 of the frame in width. Even by cropping a bit, the resolution is still fine, with even some room for a longer focal length.
I also drastically increased the acquisition time to about 1 hour and 6 minutes — compared to less than 20 minutes last time! I believe this really helped in acquiring the faintest details of the galaxy, and helped keep the noise to a lower level.
The post-processing
The post-processing also went smoothly. Surprisingly, I could keep all my subs, so the SkyGuider actually did a good job despite its internal issue.
In Lightroom:
- Change the white balance to a normal level (it was way to hot!). I used the auto mode, which did a fine job!
- Export the RAW files to 16-bit TIFF files
In DeepSkyStacker:
- Lights: Kappa-Sigma clipping (Kappa: 2.00 / Iterations: 5)
- Darks/Offset/Bias: Kappa-Sigma clipping Median (Kappa: 2.00 / Iterations: 5)
- Dark optimisation: yes
- Alignment: automatic
What I need to improve
Of course, there are still some things that can be improved! First: the exposure time. I’m sure that once my mount is repaired, I can make longer exposures — perhaps 90 or 120 seconds?
I also struggled for some reason with my Bahtinov mask, and ended up focusing without it. The focus ring on my Canon lens also doesn’t have enough resistance, which makes focusing quite imprecise (well, it’s second hand, and an older generation). In the end, the final picture seems a bit out of focus…
I’m making progress!
If you asked me 2 years ago, I wouldn’t think I’d be able to take such a picture! I’m very happy to see that successfully photographing deep sky objects with a limited gear is possible.
Sure, you need to learn a few things, spend a lot of time trying, failing, trying again, processing, re-processing… And it’s not a cheap hobby either. But it’s possible, and I’m happy to share the results on this blog to, perhaps, spread the virus of astrophotography :)
Additional notes
While my camera was busy, I also took the opportunity to watch the Moon set with my binoculars, and it was splendid! Due to the distortions caused by the atmosphere, the Moon was quite big and wearing a nice yellow color. I wish I had an extra camera with me!
I also tried to locate Messier 33, the Triangulum Galaxy, with my binos. It wasn’t easy, but I believe I managed to see a fuzzy spot where M33 is supposed to be.
