Imaging with a Celestron 130

[AstroMuni]

Hi all,

I am brand new to imaging and this is my very first set of images using the ASI224mc attached to a Celestron 130EQ scope and mounted on a HEQ5pro to give it stability and GOTO ability. This scope (OTA) has mixed reviews as it has a spherical mirror and I had little hopes for it. But considering what I have managed to get with just around 8mins of data, its looking promising. 🙂

This image is of M81 Bode's galaxy using around 100 exposures of 5sec each. These have been stacked and post processed in SIRIL. No darks or flats have been taken. Still new to this aspect of it ....The images were captured using Ekos. Any tips on how to improve the image are welcome !

 

Edited June 15, 2021 by AstroMuni

[AstroMuni]

Here is my second image. This is M82 , Cigar galaxy taken with a similar sort of sequence 100 x 5sec. Its amazing to know that its being massively influenced by M81 causing all the starburst activity at the centre.

Any suggestions on how to improve the image are appreciated.

Edited April 7, 2021 by AstroMuni

[happy-kat]

Well done for your images from using what you have.

Flats and darkflats help with vignetting and background noise. Darks are worth trying to as you may find that's a help to your image for the camera you are using. Bias I'm not sure on but nothing lost trying.

[CloudMagnet]

The Celestron 130EQ was my first scope, and i never imagined you would ever be able to capture any decent image with it at all, so well done in getting this far!  Probably just some extra calibration images needed, definetly flats/darks will be the biggest help.

Adding more imaging time as well will help with noise reduction as well.

 

[AstroMuni]

14 hours ago, CloudMagnet said:

The Celestron 130EQ was my first scope, and i never imagined you would ever be able to capture any decent image with it at all, so well done in getting this far! 

That was exactly what I thought originally. Amazed with the results 🙂

[alacant]

On 06/04/2021 at 16:27, AstroMuni said:

8mins of data

Absolutely amazing. Love it:)

[Goldfinger]

Wow!!! Some amazing photos. Thanks for posting.

[AstroMuni]

If anyone else is using the Celestron 130 scope, please post your images here

[iapa]

3 hours ago, AstroMuni said:

If anyone else is using the Celestron 130 scope, please post your images here

I’ll see what I can find - mine is the 130SLT Alt-Az.

 

[AstroMuni]

Here are a few more images taken using the same kit in the last few weeks.

M27 - Dumbbell nebula - 50 x 30sec

M57 - Ring nebula 69 x 30sec

M13 - Globular cluster in Hercules - 25 x 30sec, gain 240; 5 x 60sec, gain 240

Edited June 14, 2021 by AstroMuni

[Padraic M]

You're doing remarkably well with the 130EQ. How did you manage to get focus with that camera - is there enough back-focus, or are you using a Barlow? I would have expected you to need one of the ZWO 'mini' cameras to get the sensor inside the focuser drawtube.

The spherical mirror is only one of the issues. I found the focuser unusable for imaging, and there's no option to upgrade except with an angle grinder. The mount is so flimsy that even with 30s exposures you'll need a wind-less night. I like your dumbbell nebula pic though.

Some people are getting really good DSO images with lucky imaging, which is normally used for planets. You will definitely get better results with more data, and with no option of guiding (or even  proper tracking) on this scope, you could aim for 1,000's of very short images? Hope your PC is up to it!

[MarsG76]

That is very good for first images... I can imagine the pictures you'll be coming out with in 6 months...

More subs will result in less noise too....

[AstroMuni]

23 hours ago, Padraic M said:

You're doing remarkably well with the 130EQ. How did you manage to get focus with that camera - is there enough back-focus, or are you using a Barlow? I would have expected you to need one of the ZWO 'mini' cameras to get the sensor inside the focuser drawtube.

The spherical mirror is only one of the issues. I found the focuser unusable for imaging, and there's no option to upgrade except with an angle grinder. The mount is so flimsy that even with 30s exposures you'll need a wind-less night. I like your dumbbell nebula pic though.

Some people are getting really good DSO images with lucky imaging, which is normally used for planets. You will definitely get better results with more data, and with no option of guiding (or even  proper tracking) on this scope, you could aim for 1,000's of very short images? Hope your PC is up to it!

Updated topic to show that its mounted on HEQ5 pro so quite stable and gives me goto ability. 🙂 I was quite restricted to very short images using the stock mount and the RA tracker.

There is enough back-focus space using the ASI224mc so havent had any issues or need for a barlow.

Focus can be a challenge and needs patience. Tools in Ekos help in getting the best focus and I get it to realign using platesolving when the drift is excessive.

Edited June 15, 2021 by AstroMuni

[Padraic M]

That makes sense - the HEQ5 would be a BIG improvement!

Definitely you will benefit from using flats and darks. You don't need bias subs for that sort of camera. SIRIL will stack them nicely for you.

Next step might be to try guiding for longer subs? I attached a finder/guider shoe to my 130EQ by drilling a few holes. It's made of tough stuff! Of course you will need a guidescope - FLO has a nice cheap astro essentials 200mm one 
https://www.firstlightoptics.com/guide-scopes/astro-essentials-50mm-guidescope-finderscope.html
and you'll need another camera too. I use an ASI290mm Mini which is ideal, or you could try the T7M from aliexpress which is cheaper.

Edited June 15, 2021 by Padraic M

[AstroMuni]

On 15/06/2021 at 16:34, Padraic M said:

Next step might be to try guiding for longer subs? I attached a finder/guider shoe to my 130EQ by drilling a few holes. It's made of tough stuff!

I am not very good with such DIY skills but may have a go sometime 🙂

Whats the advantage with longer subs? Less SNR? I am just managing with 'lucky imaging' at the moment. Not sure if 30-60sec counts as lucky though?

[Padraic M]

Yes - longer subs increase the signal-to-noise ratio. As I understand it, longer total exposure time allows you to gather more of both signal and noise, but the signal increases at the square of the noise so your image improves overall. Except for read noise (RN), which is a constant value for each exposure. If you had a lots of really short exposures where the signal value was below the RN value, your image would be swamped by the RN. If you had a single really long exposure, the impact of RN would be negligible, but your image is likely to be ruined by satellite trails, cloud, or star trails (from poor tracking). The fine balance is to take multiple exposures that are long enough to gather signal with low RN impact, and short enough to reduce the waste of poor individual subs.

Having said all of that, modern astro cameras provide very low RN values and this means that the advantage of using longer subs is decreasing as technology improves. 

[mikemarotta]

On 15/06/2021 at 10:16, AstroMuni said:

Updated topic to show that its mounted ... Focus can be a challenge and needs patience. Tools in Ekos help ...

Thanks! This was a lesson for me, for sure: It's a poor workman who blames his tools. You are getting quite a lot of good use from a telescope than many people dismiss. You also have astro-photography skills, which I have not even attempted. All in all you deserve a round of applause. Thanks, again.

Best Regards,

Mike M.

[Mogra1]

Totally agree. Great images. 

Thanks for posting🙂

[AstroMuni]

Here is my take on NGC6888 - The Crescent nebula taken as a set of 120 subs of 30sec each. Stacked and processed in SIRIL and finer detail worked in Gimp.

Edited October 19, 2021 by AstroMuni
Updated image

[bobro]

You're making a great start to imaging . My 130 reflector is a Meade Polaris - not much different from the Celestron 130 you are using. I purchased it a few years ago and have made a few mods to it to improve its imaging capabilities:

• Mirror exchanged for a SkyWatcher parabolic mirror 
• Focuser mount strengthened to take the weight of a DSLR initially (now holds a filter wheel and Altair 183M)
• Tube shortened to allow a DSLR to come to focus (not necessary for use with a dedicated astro camera)
• 1.25" Coma Corrector inside the focus tube

It would have been easier to start with a 130PDS, but not half as much fun working out the mods  🙂

The EQ2 mount made a useful start for imaging, especially after being modified for guiding. However, the lack of goto became a nuisance so the 130EQ now sits on a goto guided EQ5.

After a break with astrophotography for a while I'm now back having fun with the hobby, only recently starting to try out Siril and StarNet++. I use GIMP for processing.

You asked others using a 130EQ to post images. Below are some of mine from the last few weeks as I restart imaging. The M33 needs much more data (waiting for clearer skies), plus my Ha filter is rather old and produces large halos - hopefully to be upgraded before too long.

[AstroMuni]

8 hours ago, bobro said:

It would have been easier to start with a 130PDS, but not half as much fun working out the mods  🙂

Great images 👍 So is your mirror from the SW 130PDS?

[bobro]

1 hour ago, AstroMuni said:

So is your mirror from the SW 130PDS?

The mirror was purchased from AstroBoot - it was listed as coming from a SW 130P. I understand the same parabolic mirror is used in the 130P and the 130PDS.

[AstroMuni]

On 15/09/2021 at 10:58, bobro said:

I understand the same parabolic mirror is used in the 130P and the 130PDS.

Did you notice a big difference when you swapped mirrors? I had toyed with this idea before the pandemic hit us but wanted to understand the full potential of my scope the way its built - spherical mirror and all.

And technically your post can also be put in this one 😉

 

Edited September 17, 2021 by AstroMuni

[TerryJ]

Seeing your pics here, I am seriously considering digging out my 130EQ, the first scope I owned.

Great pics.

[bobro]

On 17/09/2021 at 11:37, AstroMuni said:

Did you notice a big difference when you swapped mirrors?

That's a good question and I will answer it as things seemed to me at the time - I couldn't find a definitive answer to what type of mirror the Meade 130 reflector possessed, although there was what looked very much like coma towards the edge of images (similar to your M27). I'm no expert on mirrors but understand that coma is a characteristic of parabolic mirrors rather then spherical mirrors. As there was apparent coma I went about making a coma corrector. The corrector made a big improvement but the result wasn't quite as good as I had hoped. I suspected the mirror wasn't the best and so installed the SkyWatcher 130 parabolic mirror. This produced the results used today. So I'm not totally convinced (but may be wrong and others may correct this) the Meade 130 did not have a parabolic mirror, though it may not have been as close to a parabolic shape as the SkyWatcher. @vlaiv is pretty good at explaining these sorts of things - perhaps he can advise regarding the mirror/coma in your images?

If you wish to experiment, a simple way to improve images from both spherical and parabolic mirrors is to make use of an aperture mask. For example, placing a card with a 108mm diameter circular hole across the front of  130mm scope with 650mm focal length will change it from an f#5 to a f#6. A longer exposure will be require to gather the same amount of light, but the image improvement could be worthwhile.

Star shapes can also be improved in software processing - very useful if a coma corrector isn't available.