First H-alpha views with Lodestar X2M

[alphatripleplus]

I recently got a new Lodestar X2 mono with a view to using it for H-alpha views of summer nebulae with my Orion 7nm H-alpha filter and C8. I've taken a couple of pics previously with the X2M, but last night was my first venture into using the H-alpha filter with the camera. Here are some stacks - total exposure 5min for each subject. Taken from my back garden.

NGC7635 (Bubble Nebula) 20x15s:

 

NGC7380 (Wizard Nebula) 10x30s:

NGC281 (Pacman Nebula) 10x30s:

Sh2-155 (Cave Nebula) 10x30s: - This one needed longer subs I think

One issue that came up for me concerned restoring saved darks using Starlight Live 3.1. Prior to taking any light frames I had saved a stack of 15sec and 30sec darks using the Dark Calibration tab.  I then started 15sec light frames and all was fine. However, when I decided to move to 30sec light frames and used the Dark Calibration tab to restore a previously taken 30sec dark as the new master dark, I found that I could not get the contrast adjustment in the Display processing tab to work no matter what I tried. The black level, white level, and brightness  sliders worked fine, but no combination of adjusting these three would help with the histogram which remained a very narrow spike, and I could not display an image. I tried exiting Starlight Live and restarting the program, but this apparently did not help, as the contrast setting would still not widen the histogram. The only way I could resolve this was to create a new master dark and save it.  Having done that, the contrast adjustment would work fine at widening the histogram. I was able to repeat this behaviour several times by just attempting to restore a previously saved dark. I did have the defective pixel removal switched on, but I doubt that was an issue. I really only noticed it last night, because in my previous two or three nights with the camera I don't think  I had attempted to restore a previously saved dark and change the exposure. Not sure if this is just my inexeperience with SL showing, or if it is an issue with SL. I am using a 32 bit Windows 7 laptop that seems able to keep up with stacking pretty well. Any suggestions as to what might be happening would be welcome.

 

Finally, many thanks to Paul for the great software - my problems are pretty minor and I love the software.

 

[HiloDon]

Hi Errol,

You must have been thrilled getting these on your first attempt with NB Ha.  Great results.

I have experienced the same problem with restoring darks.  Perhaps Paul will see this and shed some light on the problem.

Don

[alphatripleplus]

Hi Don,

Thanks for your kind comments - Yes, I'm still a long way from Mauna Kea skies, but living inside a white zone, at least the 7nm filter makes a huge difference for me on emission nebulae . I knew I wanted one after I saw your many great narrowband pics.

Good to know that I am not imagining the issue with restoring darks, but it is reasonably easy to work around.

[RobertI]

Hi Errol, fantastic results, they have come out really well with that setup, looking forward to seeing lots more!

[aparker]

Errol, great looking captures - H alpha is amazingly enabling for urban EAA.  FWIW, I was never able to get the saved darks to work in SLL either.  With the latest version you can use bad pixel removal instead, which is independent of exposure time and works as well or better than darks.

[alphatripleplus]

Thanks, Alex and Rob for the nice comments. I agree that for urban EAA and emission nebulae, the H alpha filter is a great help. As Alex suggests, I'll also test out just using the defective pixel removal tool in SL without darks - currently I am using both. Will be interesting to do the comparison.

[alphatripleplus]

On my second night out with the H-alpha filter I experimented with various sub-exposures and, following Alex's suggestion, tried using just the defective pixel removal tool in Starlight Live without taking darks. Using the same setup as before, here's a 5min stack  on the Crescent Nebula with no darks:

 

NGC6888 (Crescent Nebula) 20 x15s:

 

[MrOD]

Very nice! What reducer are You using with C8 to get near f4?

[alphatripleplus]

4 hours ago, MrOD said:

Very nice! What reducer are You using with C8 to get near f4?

Thanks, I am only using a 1.25inch Antares 0.5x reducer in this particular setup. However, the distance from reducer to the Lodestar X2 sensor is about 55mm to give a 0.42 reduction factor.

[alphatripleplus]

Yesterday evening I tried the Orion 7nm H-alpha filter with just a modest 70mm achromat finder (Celestron Travelscope) that I use with my C8. I attempted to capture some of the larger nebulae as the FOV of this scope @ f/3.4 is about 1.5 degrees x 1.2 degrees with the Lodestar X2. (Note: f/ratio on all captions should read f/3.4. I used my 0.5x Antares reducer with the 70mm achro to get to f/3.4. The Celestron Travelscope is  f/5.7 without the reducer. ) Total exposures range from 6-12 minutes for each stack, and I used just the defective pixel removal tool (no darks) in Starlight Live.

NGC7000 (North America Nebula) 12x30s

 

IC5070 (Pelican Nebula) 10x45s

 

IC5068 10x45s

 

IC1396 (Elephant Trunk) 13x45s

 

Finally, took one more stab at the Cave Nebula 12 x 60s

 

[Paul81]

An amazing set of captures Errol, the Ha filter looks to be working a treat!

Thank you for the info on the darks issue. I am super busy with work at the moment but will look into the issue as soon as (I also have a bug reported by Zorin to have a look at). Hopefully will be something easy to fix, it sounds easy enough to replicate which is always the first step.

In the mean time keep the great pics coming! :-)

[alphatripleplus]

Thanks, Paul. I very much enjoy using your SL software with the Lodestar - wish I had started with it earlier!

[aparker]

On 8/24/2016 at 08:49, emustafa said:

On my second night out with the H-alpha filter I experimented with various sub-exposures and, following Alex's suggestion, tried using just the defective pixel removal tool in Starlight Live without taking darks. Using the same setup as before, here's a 5min stack  on the Crescent Nebula with no darks:

 

NGC6888 (Crescent Nebula) 20 x15s:

 

Nice Crescent.  I'm impressed with how flat the field is given the aggressive focal reduction you are using.  I used to have a cheap 0.5X FR but gave up on it because of the coma it produced.

[alphatripleplus]

Thanks, Alex. I may have gotten a bit lucky with the reducer. I've found that aberrations become much more noticeable below f/4 if using just this reducer with the C8.

[alphatripleplus]

Last night I took a quick look with the same set-up (Orion 7nm H-alpha filter, Lodestar X2 mono, 70mm finderscope/0.5x reducer) at  NGC7822, a large emission nebula complex in Cepheus. With the scope @f3.4 and a 1.5 degree x 1.2 degree FOV I thought I might be able to get both the fainter northern (top) part of NGC7822 as well as  the brighter southern part in the same field - but not quite as shown in the first frame.

 

NGC7822 16x 45s

 

In the second frame, I included just the southern emission region, Cederblad 214, which is illuminated by a young bright star cluster (Berkeley 59). Lots of dark nebulae are visible in front of the main emission nebula. A higher resolution, deeper view would also show more detail in the so-called pillars of creation star formation regions in this complex. A couple of these are barely shown near some of the cluster stars in the second picture - they appear as squiggles. A higher resolution and deeper view might make an interesting challenge for any pillars of creation fans.

 

Cederblad214 10x45s

 

[MrOD]

On ‎2016‎-‎08‎-‎26 at 00:46, aparker said:

Nice Crescent.  I'm impressed with how flat the field is given the aggressive focal reduction you are using.  I used to have a cheap 0.5X FR but gave up on it because of the coma it produced.

I got the same experience with focal reduction. I got a feeling that You really need lot of luck when You buy one

 

[alphatripleplus]

On Tuesday, August 30, 2016 at 10:21, MrOD said:

I got the same experience with focal reduction. I got a feeling that You really need lot of luck when You buy one

 

I will also add that I was surprised to find that using just the 0.5x Antares reducer on a C8 in H-alpha @ f/4.2 seems to show noticeably less aberration in the outer FOV than the identical set-up without the H-alpha filter. I guess that at 656nm, for some reason, the aberrations are not as noticeable as when the whole visible spectrum contributes to the image.

On the C8 without the H-alpha filter, I find that  using a combination of the Antares 0.5x and a Meade f/6.3 (Japan) works better than just the 0.5x reducer when trying to get to around f/4 or below.

 

[aparker]

19 hours ago, emustafa said:

I will also add that I was surprised to find that using just the 0.5x Antares reducer on a C8 in H-alpha @ f/4.2 seems to show noticeably less aberration in the outer FOV than the identical set-up without the H-alpha filter. I guess that at 656nm, for some reason, the aberrations are not as noticeable as when the whole visible spectrum contributes to the image.

On the C8 without the H-alpha filter, I find that  using a combination of the Antares 0.5x and a Meade f/6.3 (Japan) works better than just the 0.5x reducer when trying to get to around f/4 or below.

 

It actually makes a lot of sense that it looks better in H-alpha.  A significant part of the problem with pushing the FR really hard may be chromatic aberration (inherent to some degree in any refractive system), so you eliminate that by using only one wavelength. 

[alphatripleplus]

Good point, Alex. I think you are right about CA inherent in the reducer. I noticed the benefit in reduced aberrations using H-alpha with the lowly 70mm achromat, but hadn't thought much about the reducer as an achromat too.

[Dom543]

Very nice captures Errol!

Too bad I didn't see your Wizard before the weekend. It's one of the summer skies' gems and I may have missed it for the year.

Clear Skies!  --Dom

[alphatripleplus]

Thanks,  Dom. I think you should be able to do the Wizard as it is circumpolar at mid-northern latitudes. On the other hand, I haven't had a chance to see any of the southern summer gems like M17, M8, M20 as I have no view to the south, and time is running out for those this season.

[PeterW]

You guys need to mosaic or get even shorter focal length lenses... there are plenty of big cool nebulae up there, which as you saw with 7822/ced214 just need a bigger FoV to see. Point anywhere round gamma Cygnus and see what you can pull in. Cepheus is also a rich ara a as you've found out. 

 

cheers

 

peter

[alphatripleplus]

4 hours ago, PeterW said:

You guys need to mosaic or get even shorter focal length lenses... there are plenty of big cool nebulae up there, which as you saw with 7822/ced214 just need a bigger FoV to see. Point anywhere round gamma Cygnus and see what you can pull in. Cepheus is also a rich ara a as you've found out. 

 

cheers

 

peter

Funny you should mention that , Peter, as I do have an old 58mm f/1.8 SLR camera lens that I have been able to mount the H-alpha filter behind. That would give a considerably larger FOV. The old reason I haven't used it yet is that I have to securely mount it to my scope or mount. I'm working on it, but it may be a while before I'm ready to shoot. Will definitely give it a try though.

[alphatripleplus]

I took out my Orion ST80 for the first time last night with a 7nm Orion H-alpha filter and Lodestar X2 mono and Antares 0.5x reducer for views of some of the brighter emission nebulae. With the reducer and the X2 mono, the ST80 operates at exactly f/3.0 and yields a FOV of 1.5deg x 1.2deg. I think the views are sharper with the ST80 than with the Celestron Travelscope that I've also used, and I see a small degree of aberration in some of the corners of the field. Considering this is only an achromat, I'm happy with the views.

 

I used the latest 3.2 version of Starlight Live, took darks but no guiding, and I stayed with fairly short exposures - 30sec and 45sec subs -with no total exposure over 9 minutes. Towards the end, with the Veil Nebula pics, I was getting tired and battling a couple of clouds and mislabeled these as ICs rather than NGCs in the caption. Also oriented the pics so that north is up.

 

NGC281 (Pacman Nebula); 12 x45s:

 

IC1396 (Elephant Trunk Nebula); 12 x 45:

 

NGC7000 (North America Nebula); 12 x 30s:

 

 

IC5070 (Pelican Nebula); 15 x 30s:

 

IC1318 (Part of this huge complex surrounding Sadr in Cygnus); 12 x 30s:

 

 

NGC6992 (Eastern Veil Nebula); 12 x 30s:

 

NGC6960 (Western Veil Nebula); 8 x 30s - clouds rolled in:

 

[PeterW]

Very nice, more please!

 

peter