M52 with a faint bubble

[gonzostar]

Hi This is a version of The bubble, M52, and NGC 7538

I think maybe more data is needed to extract more detail? 

Duration 9.5hours - 300s lights., Darks, flats and bias frames also taken

Guided with PHD2 and processed in PS Cheers thanks for looking,

 Telescope - 102mm APO ES refractor on a AVX mount Camera- Canon 70d unmoded iso800 with a IDAS-D2 filter.

and of course any improvements welcome Dean

[Paul M]

Very nice!

I imaged that area quite a few times last year because the very interesting nova nearby. I see its still there in your image but much diminished now.

My Bubbles were very much like yours. I suspect that it's a subject that benefits from narrow band imaging. I find that once I've controlled sky glow and gradients there is little left of the nebulosity. So maybe a dark sky would benefit my own efforts. My my Optolong L Pro filter isn't helping me much I feel.

[Rallemikken]

8 minutes ago, gonzostar said:

I think maybe more data is needed to extract more detail? 

No, you need more focal lenght. With a DSLR this is as good as it gets. Very nice image btw. Looking forward to image this myself. If I get 120 good subs, it seldom pays off to use more time on a target. My simple (and humble) thumb of rule. The rain is drumming on my tin roof as I speak. I'll do an attempt with my SW 200 PDS when it dries up, afraid even that will be to short.

[Rallemikken]

As an afterthaught, 300 seconds is 5 minutes. The only time I expose so long is when I shoot with my longest scope (1000mm) and a barlow. In my experience, the advantage of added data (or SNR if you will) must be weighted against swollen (or bloated) stars. Keep an eye on FMWH (or whatever it's called), if it gets above 5 you have reached a critical point. Good guiding helps, but a crop-sensor DSLR don't tolerate much. I also image with a Canon 5D MkII, fullframe, and its a HUGE difference. See if you can get your hands on one, but then, the handicap you have regarding short focal lenght get's even worse....

[gonzostar]

15 hours ago, Paul M said:

Very nice!

I imaged that area quite a few times last year because the very interesting nova nearby. I see its still there in your image but much diminished now.

My Bubbles were very much like yours. I suspect that it's a subject that benefits from narrow band imaging. I find that once I've controlled sky glow and gradients there is little left of the nebulosity. So maybe a dark sky would benefit my own efforts. My my Optolong L Pro filter isn't helping me much I feel.

Thankyou I forgot about the nova 🙄 

Agree it needs a dark site. Apparently my site is bortle 6, so agree with the gradients issue. Frustrating as i think there is much more to offer. May try a few more subs next year?

[gonzostar]

15 hours ago, Rallemikken said:

No, you need more focal lenght. With a DSLR this is as good as it gets. Very nice image btw. Looking forward to image this myself. If I get 120 good subs, it seldom pays off to use more time on a target. My simple (and humble) thumb of rule. The rain is drumming on my tin roof as I speak. I'll do an attempt with my SW 200 PDS when it dries up, afraid even that will be to short.

Thanks for your reply. Will look forward to your attempt.  I guess its a object that needs a sky darker then bortle6. 

[gonzostar]

14 hours ago, Rallemikken said:

As an afterthaught, 300 seconds is 5 minutes. The only time I expose so long is when I shoot with my longest scope (1000mm) and a barlow. In my experience, the advantage of added data (or SNR if you will) must be weighted against swollen (or bloated) stars. Keep an eye on FMWH (or whatever it's called), if it gets above 5 you have reached a critical point. Good guiding helps, but a crop-sensor DSLR don't tolerate much. I also image with a Canon 5D MkII, fullframe, and its a HUGE difference. See if you can get your hands on one, but then, the handicap you have regarding short focal lenght get's even worse....

But guiding maybe easier? My FWHM is around 3-5. I discard any frames with higher anyway. When i get to 60 subs, i tend to  add more say 12 then start discarding bottom 3 or so 

[Rallemikken]

6 hours ago, gonzostar said:

My FWHM is around 3-5. I discard any frames with higher anyway.

Don't look yourself blind on FWHM. Especially if your subs arn't consistent. I use Siril for stacking, and make a pause after preprocessing, and set the stacking parametres manually. Siril present a basic plot with curves for FWHM and star roundness. What it does not say anything about is how exposed, or how light each sub is. This is by far the most important thing to consider. If a haze or thin cloud drifts over the rig, this sub will likely be a little lighter than the one before and after. The histogram will shift right. But the stars will be smaller and sharper, while the details you strive for gets washed out. I use Linux, and it has a very lightweight and snappy image viewer (Geeqie) I use on the raw Canon subs BEFORE I start the stacking software. I first view them as icons in a grid, and delete those that are obviossly lighter. Then I set the imagesize to 100% and roll trough the dataset with my mousewheel, while I keep an eye on the same star and the histogram. Those not found worthy is deleted on the spot. Those left goes into Siril, and after preprosessing you can catch any you missed manually.

With many subs and dithering, it's easier to avoid banding, and hot pixels if you are a little lazy. Must admit that my darks and biases is reused for an extensive amount of time..... I ditrher for each 5 subs when I expose 1-2 min, with fever but longer subs you must dither for more often to get the same effect and the variation will be less.

[gonzostar]

Thanks for tips and ideas's. Will look into Siril 

I dither every 4 subs, And agree i've being lazy lately with the darks and bias frames.