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Deflavio

Visiting New Zealand

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Posted (edited)

Hi everyone, 

I have been experimenting with EAA for the last year or so. Living near London, I still find incredible that I can get galaxies or nebulae on my laptop in few seconds using just a small telescope and EVEN without worrying too much about accurate tracking! If I only think at my "observations" when I was a child on the wobbly 114/900...  ? 

Anyway, last month I was lucky to travel around New Zealand while visiting my wife family. I always wanted to look at the southern sky so I decided to put together a very minimal setup that I could fit in my backpack/luggage without leaving out too many clothes! The setup is the following:

  • ZWO ASI 224MC,
  • SW AZ-GTI mount,
  • SW Evostar 72ED
  • K&F Concept 62'' Compact photographic tripod  (...just to recreate that wobbly feeling of my youth)

and this is how it looks when assembled:

 

IMG_1753.jpg.0e7d8ac13fd8c02226ef5beb317f52af.jpg

 

Here below a quick report of some sessions while traveling through Hawke's bay (great vineyards...) and Coromandel (beautiful beaches and nature!)... I have to say I was really impressed by how dark was the sky. I could see by eye the dark patches of dust within the milky way  and satellites were swarming everywhere. It was great! Also, I was shocked at how quickly images were forming on the screen. Just few averages were enough to clearly see many details... Used to the London sky, that is a surprise for me. 

Please note, I'm still learning my way to EAA and the following images have some obvious/silly errors... but I still like them. Starting from clusters...

 

Omega_Centaurus_46frames_253s.thumb.jpg.4e6de374ab31be610e1f9256b9cc56a8.jpg

Omega Centauri 46x5.5s  Gain 352, dark frames subtracted.  Is it just my focus bad or the ED72 has a bit of blurring in the red?

 

NGC3532_12frames_63s.thumb.jpg.36ba5edc60e851049f5186ee111641ca.jpg

NGC 3532  12x5.3s  Gain 353,  Astronomik UV+IR L3 filter, dark frame subtracted but wrong frame (I left a 10s frame from a previous session !!!)

 

Pearl_25frames_132s_crop.thumb.jpg.1a6399b9b88e54c6c128869410e9d6e0.jpg

The Pearl, NCG 3766, 25x5.3s  Gain 353,  Astronomik UV+IR L3 filter, dark frames subtracted but again 10s dark frame, doh!

Edited by Deflavio
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and galaxies...

Centaurus_45frames_247scrop.thumb.jpg.cda874e1837e31004456685fc5d97cb3.jpg

Centaurus A  45 x 5.5 s, gain 352, dark frames subtracted (the right one this time!).  Histogram slightly adjusted.

 

 

Antennae_Galaxies_51frames_510s_crop.jpg.498d86109c4d16568dbcb21bc9746068.jpg

Antennae Galaxies  51 x 10 s, gain 352, dark frame subtracted. Slightly cropped and histogram adjusted to enhanced the tails of the galaxies... if you believe it, they are there... ?  

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...and nebulae

Eta_Carinae_46frames_243s.thumb.jpg.b6c510f945897b5569e2450f7a795fe5.jpg

Eta Carina nebula   46 x 5.3 s, gain 353 Astronomik UV+IR L3 filter, dark frames subtracted but again using the 10s dark frame.

 

Tarantula_46frames_243s.thumb.jpg.ea935388e49011a279e8645d534674be.jpg

Tarantula nebula in the Large Magellanic Cloud:   45 x 5.3 s, gain 353 Astronomik UV+IR L3 filter, dark frames subtracted (using the 10s dark frame).  Considering that this is a nebula from "another galaxy" that's a big nebula!

 

 

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Fantastic shots. How lucky to see the southern hemisphere sky.
You will have some good memories of the trip to your home

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Nice journey, thanks for sharing these...

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These are seriously great captures, I'm amazed at what that setup can do, you've hit on a really good combination there. Do you use the scope at its native F6?

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Posted (edited)

Thanks, yes it was really nice to do EAA on the southern sky and enjoy the country side during the day. I already miss that.

@RobertI yes all of the images are at the native focal length. I had with me a cheap 0.5X reducer but after experimenting a bit I didn't like much the final image (still a bit of distortions at the edge of the frame). Since I was not really struggling with time in getting images I decided to stick to the long focal length. True my histograms were very much on the left side on sharpcap but just within the "green" area...I didn't want to push my luck with long expositions on the basic tripod.

One thing that really surprised me and I don't yet fully understand is how fast it was to get to a final image compared to my observations from London. I have never done EAA on a real dark site so I can't compare but I think the dark sky + the UV-IR filter (needed to remove some red halos around some stars) helped to keep a real black background...and maybe without any background to fight everything shows up faster, is that right?  E.g. The Eta carina nebula really shocked me. Essentially, it was already there in the live preview as soon as I slewed to it. Ahh, now I want a dark sky again!!

 

Just realised I didn't mention my software setup. Here it is

  • Synscan App Pro for WIN10  
  • SharpCap pro 3.1 . (Live stacking, Plate solving and to refine GoTo)
  • Cartes du Ciel to pilot the mount. 

Everything is running on a win10 laptop and it seems fairly stable... 

 

Flavio

Edited by Deflavio

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I think it is generally accepted that a dark sky makes the biggest difference to imaging and observing, so that probably explains it, plus some of those objects are nice and bright, but that should not detract from your achievements! I hope to see some more. ?

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Brilliant images with the scope, which I plan on getting in the next few months possibly. How did you deal with issues like field rotation with an alt az mount? Thought of doing something similar to your setup with my nexstar 4se mount actually :)

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On 23/04/2019 at 18:49, Deflavio said:

One thing that really surprised me and I don't yet fully understand is how fast it was to get to a final image compared to my observations from London

Indeed, I have done video astronomy from London with pleasing results but when I took myself and equipment to a dark site I was very much more amazed at how much deeper the view was. 

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Posted (edited)
22 hours ago, Nerf_Caching said:

Brilliant images with the scope, which I plan on getting in the next few months possibly. How did you deal with issues like field rotation with an alt az mount? Thought of doing something similar to your setup with my nexstar 4se mount actually :)

The stacking software is taking care of it by realigning each frame and rotating them if needed. You can see the effect of this on the borders of the first image, Omega Centauri. Over the full 4 minutes of the observation a bit of rotation is noticeable on the borders but with just 5/10 seconds expositions, or a bit more if you want, you can ignore any rotation issue within each frame. Field rotation is an issue for much longer expositions with alt az.

Also, one thing I really like of EAA and in general short expositions is that they are more forgiving. Even if your tracking is not great, as long as you have not star trailing in your single frame, you can still stack without ruining your data and see the object... Well, at least until your target is still reasonably inside the field of view ?

 

You should definitely try.  It is really fun and you can see so much more! 

Edited by Deflavio

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Posted (edited)
19 hours ago, Phil Fargaze said:

Indeed, I have done video astronomy from London with pleasing results but when I took myself and equipment to a dark site I was very much more amazed at how much deeper the view was. 

Yeah, that's why I'm already planning to go somewhere dark nearby again for a weekend at the end of May...  dark skies are really addicting!  

Edited by Deflavio

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Posted (edited)
1 hour ago, Deflavio said:

The stacking software is taking care of it by realigning each frame and rotating them if needed. With 5/10 seconds expositions, or even more, you can ignore any rotation issue within the frame.  Field rotation is more of an issue for much longer expositions with alt az.

Also, one thing I really like of EAA and in general short expositions is that they are more forgiving. Even if your tracking is not great, as long as you have not star trailing in your frame, you can still stack without ruining your data and see the object... Well, at least until your target is still reasonably inside the field of view ?.

 

You should definitely try.  It is really fun and you can see so much more! 

Oh understood (Did you use Deep Sky Stacker?). Only problem is that I live under light polluted skies (at low latitudes ie 20 deg north, where field rotation is more apparent) with little options for darker skies. Will many short exposures like you said work for cities as well?

Edited by Nerf_Caching

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Posted (edited)
2 hours ago, Nerf_Caching said:

Oh understood (Did you use Deep Sky Stacker?). Only problem is that I live under light polluted skies (at low latitudes ie 20 deg north, where field rotation is more apparent) with little options for darker skies. Will many short exposures like you said work for cities as well?

No, I’m using SharpCap. DSS is more for offline stacking and post processing... here all data is dark frame subtracted, stacked and histogram adjusted always live while observing. After a bit of stacking, when I’m happy with what I see, I save the image, stop stacking and move to the next target. 

As I said previously, this was the first time for me under a real dark sky and I’m very pleased with the result. I live in London, UK, light pollution is pretty bad but I can still do quite a lot of observations (when it is not cloudy!!!), many galaxies and other deep sky objects. It just takes longer to average a bit more data and also more fiddling around to find the right histogram settings, but that’s part of the fun.... 

Again, I would not worry about field rotation, if you stay with short exposures you are free from it.

Edited by Deflavio

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11 hours ago, Deflavio said:

No, I’m using SharpCap. DSS is more for offline stacking and post processing... here all data is dark frame subtracted, stacked and histogram adjusted always live while observing. After a bit of stacking, when I’m happy with what I see, I save the image, stop stacking and move to the next target. 

As I said previously, this was the first time for me under a real dark sky and I’m very pleased with the result. I live in London, UK, light pollution is pretty bad but I can still do quite a lot of observations (when it is not cloudy!!!), many galaxies and other deep sky objects. It just takes longer to average a bit more data and also more fiddling around to find the right histogram settings, but that’s part of the fun.... 

Again, I would not worry about field rotation, if you stay with short exposures you are free from it.

I see that you are using a small camera. Do you think there will be balancing problems with a dslr attached especially due to the short dovetail?

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Well, I did some quick tests and my relatively small DSLR (Nikon 5600) was balancing ok but the dovetail was close to the limit...

To be fair I haven't tried yet to do EEA using a DSRL but I just asked about that myself in another topic here below and it seems people are doing that.

 

This may require a bit more thinking since you may need to use a different combination of software and, if I got it right, if you go for short expositions and continuous live imaging, the shutter will also keep going all the time. Not sure that is something I want for my sessions and how good is for the life of the camera. I'm thinking to try maybe something slightly different for a DSLR but to avoid to go off-topic I think it is better to keep the relevant discussion about DSLR on the page/topic above. 

 

Alternatively, if you are not interested in just EEA but in more classical imaging (i.e. with off-line post processing) with Alt AZ and DSLR you can have a look also at this great post. You can see many great images there and there so many possibilities...

 

 

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