I was out in the desert on Saturday night on my third attempt to photograph the Wizard Nebula, aka NGC 7380, an emission nebula in the constellation of Cepheus. On the first attempt my battery pack ran out of juice and I only got two hours of exposures. The second time I had a complete system meltdown that turned out to be caused by the failure of a $10 USB hub. Finally, on the third try everything was perfect. The sky was dark and bright; the equipment worked flawlessly; and I got about six hours of exposures.
The only problem is that the picture I ended up with was terrible. I'm at a loss to figure out what happened. The stars are all sharp and round, which means everything worked well, but the nebula itself is vague and lacks almost all detail. To make things even more inexplicable, the picture was worse than my first try where I got only two hours of exposure time. Maybe I overexposed the individual frames?
Here are both of the pictures. The top one is from Saturday. The bottom one is from a month ago. For a good amateur picture of the nebula, click here.
Hey Kevin, I'm impressed. Practice makes perfect. Keep up the good work!
Those images look pretty good to me, FWIW.
I looked at the equipment used by the amateur whom you linked. He's using a 150 mm aperture (aperture matters for resolution), is operating at close (2.1 arcseconds per pixel) to the sky's seeing limit, is using a very nice filter to remove man-made lights, and he probably processed the hell out of his picture.
A triplet, super-achromatic refractor is a hard thing to beat for bringing out faint detail. Reflectors can cover the same field with as good or better star sizes and very low color error, but the stray light issues just knock them out of the running compared to a refractor with good coatings.
All true. I have a 100 mm doublet apochromatic, which isn't as good but should still produce good results. It seems like I've gotten better results before, in fact. I'll have to noodle about this.
WOW! looks great! Can you get the Seestar and try it out?
https://skiesandscopes.com/dwarf-ii-vs-zwo-seestar-s50/
A review here https://youtu.be/pgDkkn21RbE?si=z5WAI_uLCBoR_asR
That's the multiverse flickering. You've proved it!
[edit: autocorrect turned that into the multivariate flickering, which is almost as great]
What really puts the dagger in with a twist is that AstroBackyard took his image from a Bortle 7 sky, whereas you went to Desert Center, which is what, Bortle 2? But, I'm guessing from the relative brightness of the stars in your image that you were not using 7 nm narrowband filters, and that might make all the difference. Particularly with regard to resolving detail within the nebula. Also, he has a 150 mm apochromatic triplet scope which retails for $8250 - OTA only!!! - so, all in all somewhere around $15k including the mount, guide scope, and the two cameras. Plus, he's been doing intensive astrophotography for over six years.
I learned a lot from Ed Ting's YouTube channel (https://www.youtube.com/@edting), and the first thing he says about getting into astrophotography is "Don't do it!" even as he displays his photos.
It looks like the seeing was worse in September. Take a look at some of the medium bright stars, for example the one to the right of the bright star in the upper left. You can see that in September's image the star is a bit crisper but there's an extended halo around it unlike August. That's probably enough to blur out the finer details of the nebula. You might be able to find the frames where it's worse and skip those.
Pardon my failing memory Kevin, but I cannot recall what you're working with (camera, software). I certainly agree that six hours from a dark site ought to bring out more nebulosity -- this looks as if it were shot with terrestrial camera with an IR-cut filter that blocked most of the H-alpha! It's not the lack of detail in the nebula that smacks my gob, but the area and brightness of the emission area itself.
The overall appearance suggests that you had to stretch it really hard to bring out the nebula and only got part of it to show, so either there wasn't enough signal in the acquired data or the processing went south somehow. I certainly don't think it's likely your subs were overexposed, there are certainly some bloated stars and blown-out ones but that could be just the nature of the beast if you were indeed shooting narrowband.
I don't mean to insult your intelligence but Bog knows I've made this kind of goof in the past, is it possible you had in the wrong filter? (If you're shooting something like an L-eXtreme on OSC, forget I spoke -- I'm a filter-wheel-and-mono guy.)
Aperture is not the issue here. My 70mm turns in quite fine results*, thank you, when paired with a camera that gives a good image scale. Unless you're doing planetary work, seeing effects mean that you never get anywhere close to the Rayleigh limit of your optics. For DSO, a bigger scope merely means you get a longer focal length without getting up into absurd focal ratios.
Be happy to have a whack at your stack, if you like, Kevin. My contact info's in my profile.
----
*https://www.astrobin.com/ksue9g/B/
I'm not trying to brag -- that image certainly has its flaws! But I think it supports the assertion above.