First Run with the Esprit 100ED Field Flattener - California Nebula in Ha.

[CKemu]

I recently got a new mount, moving from NEQ6 to EQ6r-Pro (The NEQ is still in service, but for my observing/bar star parties). Also went from the ATIK414ex to the 490ex and with a bigger sensor comes little eggy stars in the corners, so got the matched field flattener for my Esprit 100ED.

...learning did then occur!

Never even thought about back focus and upon realising my ATIK stack of hardware came to 59mm - BEFORE any adapters are involved, I had some lessons to learn.

1x ZWO OAG2, 1x 2mm M54 to M48 adapter and 2.2mm of spacers later - I got my first light with this stack, on an object I've never actually tried to image before. Image is 5 x 1200s in Ha.
 

[Richard_]

That mount and guiding is spot on to give you 1200s subs! The image looks really clean, are you going to add other narrowband/colour channels or are you keeping it mono with just Ha? 

[CKemu]

11 hours ago, Richard_ said:

That mount and guiding is spot on to give you 1200s subs! The image looks really clean, are you going to add other narrowband/colour channels or are you keeping it mono with just Ha? 

Thank you! Honestly the mount has performed better, but various factors made it "rough" last night due to being more focused on getting the FF/guidecam to co-operate. I plan to build a complete picture of the California Nebula, initially in just Ha, and then will go back to do OIII and SII.

Just need to figure out how many panels to build the shot, and how many 1200s subs per panel.

[Richard_]

I've attempted two mosaics in the past. The first one on the veil nebula, the other on M42 Orion. I think the sweet spot for me was about 45 minutes of data per panel to allow them to merge well in pixinsight merge mosaic tool. 

For the Orion data, I think I had about 25 mins of data for each of my 3x2 panels. There wasn't enough data as there were issues with star alignment between panels with bright stars (see the weird artifact on the right). Due to weather and trees getting in the way, I wasn't able to add more time so I never finished this. 

For the veil nebula, I shot a 2x2 and added in some existing data as a centre panel which overlapped all four panels. 

The centre and top left panels were similar enough in gradient and background noise to cause no issues, but I had less time on the other three panels and you can see some artifacts around bright stars which border between other panels. Eventually, I ended up with about 45 mins on each corner panel with and the end image aligned perfectly fine without issue on the bright stars. There is a slight difference in background gradient, but that's likely caused be me

[CKemu]

17 hours ago, Richard_ said:

I've attempted two mosaics in the past. The first one on the veil nebula, the other on M42 Orion. I think the sweet spot for me was about 45 minutes of data per panel to allow them to merge well in pixinsight merge mosaic tool. 

For the Orion data, I think I had about 25 mins of data for each of my 3x2 panels. There wasn't enough data as there were issues with star alignment between panels with bright stars (see the weird artifact on the right). Due to weather and trees getting in the way, I wasn't able to add more time so I never finished this. 

For the veil nebula, I shot a 2x2 and added in some existing data as a centre panel which overlapped all four panels. 

The centre and top left panels were similar enough in gradient and background noise to cause no issues, but I had less time on the other three panels and you can see some artifacts around bright stars which border between other panels. Eventually, I ended up with about 45 mins on each corner panel with and the end image aligned perfectly fine without issue on the bright stars. There is a slight difference in background gradient, but that's likely caused be me

Fantastic mosaics, and they're something I enjoy the challenge of, but I always curse the multiplication they lead to. 20 x 20 min subs = 6.7 hours per channel - so 20 hours per panel, so about 120 hours for my estimated 6 panels for the California Nebula. Now I live in the UK, so 10-400 years of winters to get the data!

I've done a few before, my most recent mosaic was the Orion nebula 2 years ago, pretty much the last project I undertook as my camera died and I drifted out of the hobby for a bit (life etc)

 

 

This was 6 panels, with the 414ex, so small image and sensor crop lead to the larger panel count, might re-do this with the 490ex - I live in Bortle 4 skies, so perhaps increase the exposure time on this to.