Lagoon and Trifid

[DaveS]

This was a short run to try out my mobile wide-field rig. Leitz 180mm f/3.4 Apo-Telyt-R on ASI 183 at -20C with 5 pos wheel, ZWO RGB and Baader L and H-alpha filters on Star Adventurer (Dark Frame optimised)

20 mins each RGB in 60 sec subs, and 10 mins H-alpha (Before a tree got in the way), calibrated with Darks only. Given Trichromy and DDP. H-alpha added to the Red channel. Finally binned 2x2 for upload here

Problems: Star trailing, I thought I had the PA on, obviously not. Focus / Blue Bloat, looks like I need to focus each filter separately at f/3.4, plus more care with the Bahtinov Mask. Thought it was spot on, but very slightly off.

Will have another go, maybe tonight.

[haitch]

52 minutes ago, DaveS said:

This was a short run to try out my mobile wide-field rig. Leitz 180mm f/3.4 Apo-Telyt-R on ASI 183 at -20C with 5 pos wheel, ZWO RGB and Baader L and H-alpha filters on Star Adventurer (Dark Frame optimised)

20 mins each RGB in 60 sec subs, and 10 mins H-alpha (Before a tree got in the way), calibrated with Darks only. Given Trichromy and DDP. H-alpha added to the Red channel. Finally binned 2x2 for upload here

Problems: Star trailing, I thought I had the PA on, obviously not. Focus / Blue Bloat, looks like I need to focus each filter separately at f/3.4, plus more care with the Bahtinov Mask. Thought it was spot on, but very slightly off.

Will have another go, maybe tonight.

That's pretty low in the sky I imagine from West Dorset. I've just had a similar go at it but from Central France with my Eos M50 and 70-200 f2.8L (@ 200mm) and found it close to the limit of what the atmosphere would allow.

[haitch]

I'll post mine in a separate thread

[carastro]

I have found that the guiding can sometime struggle with such low targets.  

Carole 

  

[tooth_dr]

Thats nice Dave despite the issues with the image.  Have you tried 60s second before?  I was shooting with my SA the other night at 180mm, and I only did a very rough PA by eye through the polar scope.   I found that after 25s I started to get very slight trailing

[DaveS]

@haitch Yes, it's just skimming the southern horizon. I can't get this from my back garden, I had to park the tripod out in the road at the front, sheltered behind my car where I have a very low horizon. Fortunately, not only are there no street lights here, the next lot looking south are in France, 300km away.

@carastro This was tracked, not guided which is the next thing to look at, while trying to keep the costs down. I have an old QHY5-II and PHD2 on my lappy. May add a 30mm finder-guider from Astro Essentials and a multi-way shoe.

@tooth_dr Thanks. I've not tried 60s with the SA and 180 before. I have tried 120 sec (I think) at 35mm, and maybe 60 sec at 90. My last trial was 30 sec exposures with the 180 and my Fuji XT-1, which came out well. May try more 30 sec subs, possibly at a higher gain.

 

I don't want to spend too much on this, but I am considering an ASIAir Pro for mount / camera control, but it's money! May also buy a new guide camera.

[DaveS]

Focus wasn't helped by focusing on Luminance, which is a Baader filter, then imaging through ZWO which are a different thickness. Dur...