EyeGuy
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Field Flattener and back focus distance question
EyeGuy replied to Neko's topic in Discussions - Scopes / Whole setups
Man - that is seriously useful. Thanks for posting this. Suddenly makes sense. Barry -
So I finally got my Vixen SXP rig set up the way I want - literally 10 minute set up time. This is 6 hours and 45 minutes integration of 81 X 5 minute subs taken with a Canon EOS Ra through a Tak Sky 90 on a Vixen SXP with an OPT Triad filter last night. All processing in PixInsight. Comments / criticisms welcome. Barry PS - my first ever automated meridian flip on APT while I slept! Good times.
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IC 1396 - Elephant Trunk Nebula - Reprocessed
EyeGuy replied to EyeGuy's topic in Imaging - Deep Sky
Thanks Steve. It's a real treasure trove of objects. What do you think of the reprocess? Better / Worse? Barry -
That's a stunning image. Beautifully captured and processed. Jaw-dropping stuff. Every time I see an FSQ 130 image I feel angry at myself for not getting one when they were available. *glass jealousy intensifies* 🙂 Barry
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This was 3 night's work with a Takahashi Sky 90 on a self-guiding Vixen SXP mount from the back yard. I used a triad filter on a Canon EOS Ra at ISO 800. 157 x 5 min subs = 13 hours integration time (my longest yet by far) Processed in PI and PS. I drizzled again (sorry Vlad - I just can't help myself) and was pretty happy with the level of detail from a 407mm FL. The wide shots show a fair bit of astigmatism in the corners - but I thought the Sky 90 did pretty well. The Vixen SXP is a dream to use - it's lovely to be able to do the entire thing without a laptop. Annoyingly I had the mount in the wrong mode (Dec off) for 2 nights so the stars are a bit eggy, but I didn't have the heart to throw out the data. I think the smallest crop is a bit reminiscent of the dementers in Harry Potter. Barry * Edit - I had another go at reprocessing this. I think I left the originals far too muted. I redid them as LRGB, with the red channel (HA really) as the luminance layer). Thoughts anyone? Better before of after? Barry
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- elephant trunk nebula
- vixen sxp
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Lovely image. I love your colour balance and you've left a nice natural, soft look. I was going to shoot this target the other night too and thought I'd set up 2 rigs for the first time. I ended up cocking up both setups, imaging with neither and then taking them both down as the clouds rolled in. Barry
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That's a real beauty. Lovely framing too. I have the colour version of that camera - it takes a bit of getting used to but I'm definitely liking it more and more. I can't wait to give the veil another crack later in the year. Barry
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Thanks for taking the time to give that very detailed description, Vlad. It's very much appreciated. I remember trying to process some Nikon NEF raw files as individual mono, but I screwed the whole thing up and it ended up a mess. I could try to give it a go again with what you've said above. I don't think I'd bother on the data from the Needle - especially since it's perfectly sampled for my setup, but I have a Moravian OSC which I kind of bought in error. I read the 6um pixel size and thought that sounded great - but pixel size on normal commercial cameras is very different to pixel size on astronomical cameras. When you figure the bayer matrix in the real pixel size is 12um - which is badly undersampled. (at least, I think this is how it works - anyone can correct me if I'm wrong). Anyway, I'll give that a go like you suggest - but I think I'm coming down with Covid-19 now so we'll have to see... Thanks again, and best wishes, Barry
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Thanks for that - in this instance the camera was a Canon EOS Ra. My typical workflow for preprocessing is Adam Bloch's method. It's basically the same as the script, but done manually to look for trouble as you go. So the debayering happens, I think, as PI loads the images. How would I go about processing the greyscale images and then combining? I'm afraid to mess with the camera raw loading options as the last time I did that I screwed everything up 🙂 Barry
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I tried Bayer drizzle - but PI told me it wasn't a Bayer image, though it was, so I gave up quickly and just went with the usual drizzle. If I get a chance I'll process it without the drizzle and post here for comparison - maybe a very small closeup would be useful. You're probably right that it made no difference - but it sure makes enormous files.
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It's in the filename. When I'm processing I name the file according to what I've done at each step so I can retrace. Vlad clearly has eagle eyes. 🙂
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I don't, I'm afraid, and it would be v hard to show on the website. I was of the same opinion until this image, and it's not like the difference was striking, but I was convinced it was a little better with drizzle when I examined the 2 with same zoom settings in PI. Maybe just my imagination as the sampling really is just about spot on for my scope. Barry
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Thanks! Glad you like it. I'm really starting to like the EOS Ra.
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Well spotted! It's funny - I didn't think drizzle would make any difference at all because the sampling is about right with 5.34um pixels, but it definitely seemed to increase the detail a tiny bit when I zoomed in, and it made edges more pleasing. Barry
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It was a TEC 180 FL - I tagged it at the top of the thread but the tags aren't very conspicuous on SGL. Barry
