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Starting from zero... Literally

EAA imaging SCT refractor mount Celestron beginner dso
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#1 Daddy-O

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Posted 13 August 2020 - 04:44 PM

Hi Everyone!

 

Let me start out by saying I am a complete novice to all of this. How much of a novice? I just started reading CN early last week trying to absorb everything about telescopes I can. We have a telescope we recently dug out of the basement, but it is very old and frankly not much more than a toy.

 

So we are currently looking for our first "real" telescope. I recently posted on the beginners forum to solicit ideas from more experienced folks on the correct direction we should go. After doing research on CN I stumbled upon EAA. All I can say is WOW! Some of the captures you all are getting are simply amazing! My family and I would love to do this--

 

--eventually.

 

I see a lot of posts from folks saying they have scopes and mounts and want to start EAA with what they have. Makes sense. Best to use what you have to see what is possible. We are at the beginning with the thought that 'no one wants to buy a bunch of stuff only to find out it is not optimal for EAA when they finally decide to go that direction'. So, after posting on the beginners forum and gaining a lot of valuable input, we have determined it might make sense to buy two scopes to start. One for my son to work (age 12) and one for me.

 

I have narrowed down some scopes that might work for us for visual now, but COULD potentially be used later for EAA. Now I need some input to make a final decision.

 

I like the idea of getting a refractor that my son could use with a simple Alt-Az mount for now. Here is one that is a contender: https://www.bhphotov...ctor.html/specs

 

From what I understand (again, I am about as much of NOOB as possible with this so please forgive me if I am not saying something correctly), we need something fast to capture images in real time. This scope is an F/5 and with a 6.3FR could go to F/3.2. Would something like this work for EAA eventually?

 

For the scope I would be using I am looking at either a 6SE, Evolution 6, or some kind of a goto dob. I would like goto so it would be easier to find things (I forgot to mention we are in Bortle class 6). It seems a lot of folks use the SCT's for EAA. Not optimal, but it can be made to work with various focal reducers.

 

I'm wondering if the Skywatcher Startravel 120mm could be used on the 6SE or Evolution mount for EAA? Is there enough clearance at the zenith?

 

If not, would this mount work instead: https://www.adorama....nmpi-google-dsa

 

Thank you in advance for any advice!



#2 Alien Observatory

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Posted 13 August 2020 - 05:05 PM

I have a TeleVue 101 mounted on a SE Mount.  At 10 or 11 pounds (max for the mount) it needed to be balanced by adding a 1lb weight to the telescope as I moved the telescope forward on the mount to allow for the telescope to go higher in elevation as the diagonal would hit the mount base.  I started at 50 degrees maximum and now can get 65 degrees of elevation.  

 

It is good enough for now (moon and planets), but I will be putting it on a wedge in a few days so I can get to 90 degrees of elevation.  The scope is a F5.4 so it is much shorter than the SW 120.  So a quick answer is no it will not work on a SE mount.  You are better off with a SE 6 or 8 SCT to start with...  Pat Utah smile.gif


Edited by Alien Observatory, 13 August 2020 - 05:08 PM.


#3 Daddy-O

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Posted 13 August 2020 - 09:57 PM

Thank you Pat.

 

I take it the evolution mount is the same specs?



#4 Alien Observatory

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Posted 13 August 2020 - 10:18 PM

The EVO mount is 25 lb capacity and ~2 inches of more clearance at Zenith...but the 120 is a  bit longer scope than the TV 101 (maybe 4" longer), and it will still might not work without a wedge.  The asking price for a SE wedge is about $375 so I am doing a DIY wedge for about $150...  If you are adventurous give it a try and look at CN Classifieds for a used unit if available...

Pat Utah smile.gif

Attached Thumbnails

  • TV 101 on SE Mount and TV Tripod.jpeg

Edited by Alien Observatory, 13 August 2020 - 11:17 PM.


#5 GazingOli

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Posted 14 August 2020 - 02:45 AM

Hi,

 

welcome to the show! I am an astronomer for about 2 years now and got into EAA some months ago. So I am not really expienced but as I got my first EAA setup just working really well I would share my experience.

 

 

> I like the idea of getting a refractor that my son could use with a simple Alt-Az mount for now. Here is one that is a contender: https://www.bhphotov...ctor.html/specs

 

The Startravel 120 is a nice scope for widefield viewing (I had one) BUT it is still heavy to handle for a 12 year old AND it is not really a good choice for EAA! The reason is the chomatic aberration which can give you a hard time for live stacking - the stars are too blurry and the live stacking software might have problems to idenitify stars for software alignment.

 

> From what I understand (again, I am about as much of NOOB as possible with this so please forgive me if I am not saying something correctly), we need something fast to capture images in real time. This scope is an F/5 and with a 6.3FR could go to F/3.2. Would something like this work for EAA eventually?

 

f/5 is perfect for live stacking with a good scope however - why should you want to go for f/3 and worsen the chromatic aberration when using an Fraunhofer scope?

 

First question is: what do you want to observe and what focal length you need? Check out with the FOV calculator at http://astronomy.tools/. Of course focal ratio is an issue when it comes to Maksutov Cassegrain or SCT with f/10 or higher. But f/5 is perfect. My ASI224 cam even works perfect with my CPC800 at f/10

 

M102diffScpes.jpg

 

> For the scope I would be using I am looking at either a 6SE, Evolution 6, or some kind of a goto dob. I would like goto so it would be easier to find things (I forgot to mention we are in Bortle class 6). It seems a lot of folks use the SCT's for EAA. Not optimal, but it can be made to work with various focal reducers.

 

My CPC800 works perfect and if you go through the threads of this bulletin board you will notice that a lot of people are doing very fine with similar scopes. Celestron 6 SE will also work fine. However here it makes sense to use a focal reducer. And you are always (with any scope) limited to you FOV. To cover all celestrial objects you need minimum 3 different scopes or lenses. In my case I use a 80/480 triplet apo refractor for medium size objects, the SCT for the small ones and I am experimenting with a 50 mm photo lens for the big objects.

 

> I'm wondering if the Skywatcher Startravel 120mm could be used on the 6SE or Evolution mount for EAA? Is there enough clearance at the zenith?

 

I would recommend a shorter scope for your son. Maybe the ST102. Easier to handle, less expensive and if you want to try it for EAA then use a UV/IR cut filter. My first trial in EAA was with a ST80 and the filter helped at least a little bit.

 

> If not, would this mount work instead: https://www.adorama....nmpi-google-dsa

 

This is too weak in my option. I would rather think about the Sky-watcher Star Discovery Wi-Fi Go-To.

 

Clear Skies!

 

Oli
 

 

edit: if you wish you can read about the ladder I climbed here:

https://www.cloudyni...ast/?p=10349265

https://www.cloudyni...made-refractor/


Edited by GazingOli, 14 August 2020 - 11:59 AM.


#6 cmooney91

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Posted 14 August 2020 - 08:19 AM

I like fast Newtonians for EAA 

 

Pros:

They are by far the cheapest per inch of aperture

They are naturally fast at F4 (no reducer needed)

Purely reflective optics, no chromatic aberration, and no need to block bonus IR light

 

Cons:

They require collimation(mirror alignment) to get the best performance, but it only takes 2 minutes once you know how. 

Larger camera sensors will pickup coma(optical aberration) at the edges, but a coma corrector can fix it

 

I used a small and cheap Mead Mini lightbridge 114mm F4 newt combined with a small IMX224 sensor for my second year of EAA. It was a very well balanced combination. The small scope and small sensor would cover each other's faults, Resulting and a comfortable FOV, with minimal coma. 

Here are some examples from that combo.

 

The AZ-GTI would be be perfect for this small light weight combo. 

 

The 114mm F4 is an ~ok visual scope, but it is a little small. It does make a fantastic rich-field scope though.

 

 

My first year of EAA I used that IMX244 camera with fast F1.4  C-mount camera lenses, The wide FOV and short exposures let me live stack binocular-like views from a stationary tripod. The simplicity of that really helped me learn how run the stacking software, without adding all of the complexity of scope and mount management in the mix. I highly recommend playing around with one, the lens was ~$15 and it was a ton of fun, and made learning easy. 


Edited by cmooney91, 14 August 2020 - 08:55 AM.

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#7 GazingOli

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Posted 14 August 2020 - 08:31 AM

My first year of EAA I used that IMX244 camera with fast F1.4  C-mount camera lenses, The wide FOV and short exposures let me live stack binocular-like views from a stationary tripod. T

That is about what I am trying to do right now to get access to big celestrial objects. However I am not sure how it will work out... waiting for good weather.

 

20200804_112702kl.jpg

 

Got a 50 mm f/1.7 with T2 thread - some spacers - ASI224 directly adapted. Mounted with a shelf bracket to the finder shoe of the CPC. As simple as can be.

 

CS.Oli


Edited by GazingOli, 14 August 2020 - 08:32 AM.

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#8 GazingOli

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Posted 14 August 2020 - 08:40 AM

also put together a very simple mount from some leftover wood pieces

 

DSC03252kl.jpg

 

just put it on a table and adjust it: the two pieces are bolted together so that you can adjust the height (alt) and the friction will keep it in place.

 

CS.Oli


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#9 cmooney91

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Posted 14 August 2020 - 09:10 AM

That table top mount for the 50mm looks like a lot of fun. At a blazing fast F1.7 I'm sure it will work out.

Here is a thread with some small fast camera lens experimentation.

 

 

I like to use mine along side the big scope with a second camera to act as a powerful digital finder scope.


Edited by cmooney91, 14 August 2020 - 09:12 AM.

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#10 Daddy-O

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Posted 14 August 2020 - 11:42 AM

 

The Startravel 120 is a nice scope for widefield viewing (I had one) BUT it is still heavy to handle for a 12 year old AND it is not really a good choice for EAA! The reason is the chomatic aberration which can give you a hard time for live stacking - the stars are too blurry and the live stacking software might have problems to idenitify stars for software alignment.

 

 

Thanks for your responses. This is odd and maybe it is a terminology thing. I really mean to say "he could operate it" not necessarily move it outside and into position. I can assist him with that part. This scope was recommended in the beginners forum as one member stated his daughter is 6 and operates it fine. That post is here: https://www.cloudyni...for-the-family/

 

I see what you mean about CA and that was also mentioned. You mentioned the Mead 102. Was hoping for something in the 120mm range. Any other recommendations? I'm also thinking it would be a quick "grab-and-go" scope for me as well if I don't want to get out the 6se and let it cool, align the thing, etc.



#11 Daddy-O

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Posted 14 August 2020 - 11:47 AM

I like fast Newtonians for EAA 

 

Pros:

They are by far the cheapest per inch of aperture

They are naturally fast at F4 (no reducer needed)

Purely reflective optics, no chromatic aberration, and no need to block bonus IR light

 

Cons:

They require collimation(mirror alignment) to get the best performance, but it only takes 2 minutes once you know how. 

Larger camera sensors will pickup coma(optical aberration) at the edges, but a coma corrector can fix it

 

I used a small and cheap Mead Mini lightbridge 114mm F4 newt combined with a small IMX224 sensor for my second year of EAA. It was a very well balanced combination. The small scope and small sensor would cover each other's faults, Resulting and a comfortable FOV, with minimal coma. 

Here are some examples from that combo.

 

The AZ-GTI would be be perfect for this small light weight combo. 

 

The 114mm F4 is an ~ok visual scope, but it is a little small. It does make a fantastic rich-field scope though.

 

Great pics! I really like galaxies and that is likely what I would be interested in for EAA.

 

Although I did not mention it in the first post, I was also looking at these options to start with. Thoughts? Could the tabletop model be refitted on an Alt-Az mount later?

 

https://www.amazon.c...97423548&sr=8-4

 

https://optcorp.com/...mhoCzDAQAvD_BwE



#12 GazingOli

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Posted 14 August 2020 - 12:07 PM

I really mean to say "he could operate it" not necessarily move it outside and into position. I can assist him with that part. This scope was recommended in the beginners forum as one member stated his daughter is 6 and operates it fine.

If it is just about operating and you got an easy-to-handle mount alsmost any refractor will do.

 

You mentioned the Mead 102.

No, I mentioned the ST 102 which is the Skywatcher Startravel-102 OTA / Rich Field Refractor 102/500mm.

 

Anyway - if you want 120 mm aperture the Skywatcher (or similar) ST120 is the most compact and lightweigth of this class. And with 2" eyepieces its a great richfield scope.

 

CS.Oli
 


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#13 cmooney91

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Posted 14 August 2020 - 12:53 PM

Both of those 130mm(~5") F5 newts have an interchangeable dovetail mounting bar, so it is easy to swap them onto different mounts.  The Vixen porta ii mount is a very nice and easy to use visual mount for a scope this size. The table top mount is a little more crude but also easy to use, the downside is it requires a sturdy table/surface.

 

In the future you could replace either mount with a tracking mount for EAA (AZ-GTI should handle it). If you are looking for an involved DIY project, it would be possible to motorize the VIxen porta II mount with an open source project called OnStep, but it is a fairly technical exercise. 

 

For the cost of the Vixen 130 F5 porta ii kit you could get an AZ-GTI and a Meade MiniLight Bridge 114 (has dovetail) and be tracking right out of the gate.  Although for me personally, hunting and finding the objects with a manual mount and star chart is half the fun of visual, so it would be a very personal choice how you want to start. 

 

For Visual  compared to the 114mm F4, the 130m F5 would probably be more enjoyable since it has a little more aperture and a longer focal length, F5 is more forgiving with eyepieces too.

For EAA the 130mm F5 should also work (I think others have been using them), but at F5 it would be a little slower to build an image, but plenty of people are successful at F6.3.  The longer focal length will give you more zoom/resolution, but it will also reduce your FOV making learning a little more challenging. 

I think either could strike a good balance between visual and EAA. It's mostly a matter of preference. 


Edited by cmooney91, 14 August 2020 - 12:55 PM.

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#14 Daddy-O

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Posted 15 August 2020 - 08:11 AM

hunting and finding the objects with a manual mount and star chart is half the fun of visual

This is so very true. I appreciate all the great input everyone!




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