New telescope first light! The Elephant's Trunk Nebula: Bortle 8, OSC.

[Lee_P]

The first image using my new Askar 130PHQ telescope! Data was taken using Optolong L-Ultimate and Askar Colour Magic 6nm dualband filters. Imaging details below, and lots more info on my website.

 

 

* October 2022
* Bristol, UK (Bortle 8 ) 
* Telescope: Askar 130PHQ Flatfield Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Filter: Optolong L-Ultimate and Askar Colour Magic 6nm
* Mount: Sky-Watcher EQ6-R PRO
* Guide: William Optics 50mm Guidescope with 1.25″ RotoLock; ZWO ASI 120MM Mini
* Control: ASIAIR Plus
* Software: PixInsight, Lightroom,
* 330 x 120 seconds (Optolong L-Ultimate) plus 330 x 120 seconds (Askar Colour Magic 6nm)

Total integration time: 22 hours

By Lee Pullen

 

[jjosefsen]

Kudo's that is very, very nice.

[AMcD]

Very nice, Lee.

[glafnazur]

That's very well done, super image 👍

[Sunshine]

It is just beautiful!

[The Admiral]

Cracking shot! But you do have to put in the hours. Where do you find them all in our climate?

Ian

[simmo39]

V nice m8!

[Lee_P]

13 hours ago, The Admiral said:

Cracking shot! But you do have to put in the hours. Where do you find them all in our climate?

Ian

Ah, good question! I've written about exactly that here: https://urbanastrophotography.com/index.php/2021/06/14/how-to-get-long-integration-times/

[Shibby]

Excellent. Impressive what you're achieving from such a light-polluted location - gives us all hope for the future.

[Gary Clayton]

Very nice shot, how are you finding the new scope?.

[MarcuSmythe]

Very nice indeed.

[Lee_P]

2 hours ago, Gary Clayton said:

Very nice shot, how are you finding the new scope?.

It's great, and really quite something to behold in person! I'm writing a full review of it, just need a few more clear nights to produce a broadband image. Keep an eye out in the Members' Review section of the forum 😁

Edited October 26, 2022 by Lee_P

[Richard_]

Absolutely cracking image Lee, and what a memorable first light you've had with this telescope! I have no idea how you managed to get 22hrs of clear skies in October. I've maybe had 6hrs worth here in South Wales haha. Keep it up!

[Ouroboros]

A magnificent image, Lee.  Two questions occur to me. Firstly - how long did it take to calibrate and integrate 660 files? …. And what sort of computer are you using? Secondly,  I’m perhaps a little surprise at your use of 120s exposures.  That’s what I use for OSC with this camera. But I thought advice was to use longer exposures when using filters - 5 mins, 10 mins whatever. What made you settle on 120s?

PS your image has inspired me to have a go at the elephant’s trunk. I’ve always avoided it so far as being too big. 

[Lee_P]

20 hours ago, Ouroboros said:

Two questions occur to me. Firstly - how long did it take to calibrate and integrate 660 files? …. And what sort of computer are you using?

Oh yes, I actually screenshotted my WBPP Execution Monitor report, but forgot to include it on my site. Thanks for the reminder!

My computer is an i5-8400 2.80GHz with 48GB of RAM, and all my astro processing runs off an NVMe drive. So fairly beefy, but WBPP still takes an age.

 

20 hours ago, Ouroboros said:

 Secondly,  I’m perhaps a little surprise at your use of 120s exposures.  That’s what I use for OSC with this camera. But I thought advice was to use longer exposures when using filters - 5 mins, 10 mins whatever. What made you settle on 120s?

Good question. I experimented with different exposure times a few years back when I first got a bunch of new kit; specifically, my ASI2600MC-PRO camera and Askar FRA400 telescope, along with an Orion Sirius EQ-G mount. I found that subexposure length didn't really matter; it was all about total integration time. I settled on 120-seconds as a sweet-spot for not being too taxing on my mount, making the most of gaps in clouds, and not resulting in so many subs that it filled my PC's harddrive / melted it during processing. Sticking with one subexposure length regardless of filter or target also kept things simple. The results have always been fine (gallery here). Having said that, I'm now using a new telescope and mount, so perhaps it's time I reran the experiment just to be sure. If my mount can reliably handle longer subexposures then I could be tempted to go to perhaps 180-seconds as standard, just to keep the total number of subs down.

Edited October 27, 2022 by Lee_P

[Richard_]

49 minutes ago, Lee_P said:

Oh yes, I actually screenshotted my WBPP Execution Monitor report, but forgot to include it on my site. Thanks for the reminder!

My computer is an i5-8400 2.80GHz with 48GB of RAM, and all my astro processing runs off an NVMe drive. So fairly beefy, but WBPP still takes an age.

 

Good question. I experimented with different exposure times a few years back when I first got a bunch of new kit; specifically, my ASI2600MC-PRO camera and Askar F400 telescope, along with an Orion Sirius EQ-G mount. I found that subexposure length didn't really matter; it was all about total integration time. I settled on 120-seconds as a sweet-spot for not being too taxing on my mount, making the most of gaps in clouds, and not resulting in so many subs that it filled my PC's harddrive / melted it during processing. Sticking with one subexposure length regardless of filter or target also kept things simple. The results have always been fine (gallery here). Having said that, I'm now using a new telescope and mount, so perhaps it's time I reran the experiment just to be sure. If my mount can reliably handle longer subexposures then I could be tempted to go to perhaps 180-seconds as standard, just to keep the total number of subs down.

You're a clever guy so if you use NINA then you've probably come across this already, but there's an addon called something like "optimal exposure calculator."

If you provide the calculator with a sharpcap sensor analysis file for your camera, capture a bias frame and take an image of your target with whatever filter you're using (eg for OSC, no filter, UV-IR or dua band filter), the calculator will tell you what exposure time is required to swamp the read noise. I haven't got the documentation in front of me, but I think it also takes sky brightness into consideration (like light pollution) but I may be wrong. 

Of course, this isn't the only input into choosing an exposure time, but hopefully this helps with one portion of it

[Lee_P]

Just now, Richard_ said:

You're a clever guy so if you use NINA then you've probably come across this already, but there's an addon called something like "optimal exposure calculator."

If you provide the calculator with a sharpcap sensor analysis file for your camera, capture a bias frame and take an image of your target with whatever filter you're using (eg for OSC, no filter, UV-IR or dua band filter), the calculator will tell you what exposure time is required to swamp the read noise. I haven't got the documentation in front of me, but I think it also takes sky brightness into consideration (like light pollution) but I may be wrong. 

Of course, this isn't the only input into choosing an exposure time, but hopefully this helps with one portion of it

Sure, I've done this using SharpCap. It came out as something crazy-low like 10 seconds... just shows how bad my light pollution is! But just imagine an integration time of 20 hours composed of 10-second subframes 🥴

[Richard_]

Wow, that's steep! Ain't nobody got time or disk space for that

[scotty38]

I tried the exposure calculator quite some time back and mine resulted in a crazy long time, well way longer than my usual 300s. At the time it seemed like I must have made some sort of mistake so I just ignored it and never bothered again. I'm in a Bortle 3/4 so maybe it wasn't so far off after all and maybe I should revisit it........

[Richard_]

1 hour ago, scotty38 said:

I tried the exposure calculator quite some time back and mine resulted in a crazy long time, well way longer than my usual 300s. At the time it seemed like I must have made some sort of mistake so I just ignored it and never bothered again. I'm in a Bortle 3/4 so maybe it wasn't so far off after all and maybe I should revisit it........

Yeah, my SHO narrowband filters in Bortle 5 returned an exposure time of something like 600-700s to swamp the read noise. I'm not fond on losing subs due to a brief gust of wind (which can happen, living near the coast) so I also settled for 300s in the end as a compromise. 

[Ouroboros]

3 hours ago, Richard_ said:

Yeah, my SHO narrowband filters in Bortle 5 returned an exposure time of something like 600-700s to swamp the read noise. I'm not fond on losing subs due to a brief gust of wind (which can happen, living near the coast) so I also settled for 300s in the end as a compromise. 

600-ish seconds seems to be not untypical for filtered subs. I agree though about wind gusts.  It doesn’t take too much wind to shake my ED80 despite it being a smaller scope on a reasonably heavy mount.  

[tomato]

One of the best close in Elephants Trunk I’ve seen, an outstanding result from your location.

Using a dual rig I got 24 hrs of RGB and NB data on NGC7331 in October from my location but to date the image derived from it doesn’t do the integration time justice, but I’ll keep plugging away at it.