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Which 80mm refractor for EAA?

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#1 BarryBrown

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Posted 24 May 2018 - 12:03 PM

I'm thinking of making the jump to a small refractor to complement my EAA setup. I've never owned a "real" refractor before. What are the pros and cons of the various 80mm refractors for EAA? Specifically I'm considering the:

  • Orion ED80
  • Orion ST80
  • Vixen ED80Sf

Inspired by another EAAer here, I want to make a portable setup using the Orion AutoTracker base, which limits the size of the scope.

 

For what it's worth, I have an Atik Infinity camera.

 

Thanks for your input!



#2 Censustaker

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Posted 24 May 2018 - 12:25 PM

Also consider the explore scientific ED80. 


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#3 sg6

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Posted 24 May 2018 - 12:43 PM

Just an opinion and from someone who has little experience of EAA but I would say the Orion ED80.

 

The ST80 is I believe a fast achro refractor, so CA will be present and likely compromise the image quality.

The Vixen is to my mind just too expensive for what it is, although nice.

The Orion ED80 should be a rebrand of the Skywatcher and may have minimal CA, some people see some others see nothing, also it is a longer focal length.

 

Not really an opinion from experience as all the ones I have met have been using big SCT's and not what are by comparison small refractors.

 

May have to pick a typical object and then work back to determine if the sensor is appropriate.



#4 BarryBrown

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Posted 24 May 2018 - 12:57 PM

Thanks for your comments so far. 

 

My budget is around $500 used. I think all the scopes I mentioned are in that price range, including the Explore Scientific and the Vixen.

 

The comment about the ST80 is spot on. I had read that there was significant CA, so that pretty much rules it out.

 

My confusion stems mostly from the "ED80" term. It appears that not all scoped labeled as such are equivalent. Some are doublets, some are triplets. Some are f/7, some are f/6. Which is better for DSO?



#5 elpajare

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Posted 24 May 2018 - 01:40 PM

This is a good option too:

 

https://www.astronom...-f6_p20533.aspx



#6 Adun

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Posted 24 May 2018 - 02:08 PM

I do EAA with the very portable Orion AutoTracker, and the 80mm refractor it used to come with (sold alone as the "GoScope").

The issue with an achromat is not just CA, but the fact that chromatic aberration will manifest as "bloated stars" after 10s exposures on a very sensitive EAA camera.

The fainter stars will look fine, but most (the brighter ones) will be bloated no matter what. This also costs some DSO detail of course, but I'm not doing AP.

I've learned to live with that, and I do appreciate the way the focuser works on the Starblast/GoScope achro, which unlike R&P/Crayford, provides rather very fine focusing.

Because of this experience I'd reckon an APO would be better, but I wonder if there's a true APO alternative within your budget.

My understanding is that only a true APO (meaning a triplet) will solve the CA issue, and I don't see even a 60mm triplet under $500. Maybe used.

We'd need feedback from someone with actual imaging experience with an ED doublet to tell us whether those allegedly "semi APO" doublets really do (or not) improve CA enough for focus to be perfect and stars not bloated when imaging.

If there's a doublet that thanks to ED glass has CA under control while still being fast enough for imaging, I'd like to know which one.


What's the shortest FL you can reduce your bigger SCTs to? Answering this might help you find out which new FL would be most desireable for your 11mm ATIK Infinity.


Edited by Adun, 24 May 2018 - 02:12 PM.


#7 Howie1

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Posted 24 May 2018 - 03:42 PM

Good on you Barry. Join the portable EAA frat.

 

Your budget/pref is the Orion tracker which is Alt Az so you will be limited to short exposures and therefore not chasing AP quality.

 

Your budget/pref is to keep using the Infinity camera on it. It is also not AP quality, but built for EAA use.

 

So if I were you, I would not worry at all about folk saying you need to get true triplet APO quality and expense. Very much overkill IMO when it's to be used on portable lightweight low carrying capacity Alt Az mount like the orion tracker. Plus also very much overkill when it's to be used with an Infinity OSC. 

 

And of course, the whole idea is portability ... so carry it out the back, travel on planes, trains and automobiles or even short hikes, then the last thing I'd want is an expensive Apo to worry about damaging.

 

IMO a doublet ED80 (if its not too heavy for the Tracker mount?) will more than suffice. Google on Astrobin and the web to see many use doublets for true AP work. IE far better images than any images we get doing even fixed pier observatory based EAA. Far better images than even those doing EAA who happen to use true CDD imagers So again, I would not worry at all about triplet of quad or more high end fracs.

 

BTW, for the record there are many who get second hand ST80 with bad CA and simply use wratten yellow #8 filters cure CA and UV/IR filters to cure bloat. Still lets in more Ha than a normal IR filter so you get nebulosity goodness. But the yellow #8 filters are cheap to fix CA. See this post ...

https://www.cloudyni...mats-for-video/

 

But ... filters add to the list of more stuff to take out and about and potentially loose, and do reduce the amount of light and potentially have weird optic aberations and most importantly add to the cheap cost of an ST80 making its total cost nearly the same as a ED80 doublet!!

 

So if I were you I'd go the ED doublet path .... it will work nicely with the Infinity and Tracker and not costs heaps and not be too much of a worry about transit damage and be lighter weight, etc.

 

BTW, 12dstring FOV calc website will let you test 110 messier and all planets showing many combos of scope and camera and both yours are in there. Here's M42 and M57 and M13 thru that combo of Orion ED80 and Infinity

FOV M42 Infinity OrionED80
FOV M57 Infinity OrionED80
FOV M13 Infinity OrionED80

Edited by Howie1, 24 May 2018 - 03:46 PM.


#8 Destrehan Dave

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Posted 24 May 2018 - 05:57 PM

I'm thinking of making the jump to a small refractor to complement my EAA setup. I've never owned a "real" refractor before. What are the pros and cons of the various 80mm refractors for EAA? Specifically I'm considering the:

  • Orion ED80
  • Orion ST80
  • Vixen ED80Sf
Inspired by another EAAer here, I want to make a portable setup using the Orion AutoTracker base, which limits the size of the scope.

For what it's worth, I have an Atik Infinity camera.

Thanks for your input!
None of them! Buy s C8 if you want any hint of galaxies. i currently do EAA with 120 and a C8 humbles it.


Sent from my iPhone using Tapatalk

Edited by Destrehan Dave, 25 May 2018 - 07:37 AM.


#9 Censustaker

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Posted 24 May 2018 - 08:55 PM

Nonsense. I can detect galaxies galore on my 80mm F/6.
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#10 nother

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Posted 25 May 2018 - 03:37 AM

I use a Skywatcher Doublet ED 80 called "Photoline". It's a f7 .

Just take a look in my recent EAA posts and you will see what's possible and whats not.

 

IMG_5894.JPG


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#11 NaNuu

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Posted 25 May 2018 - 04:04 AM

None of them! Buy s C8 if you want any hint of galaxies. i currently do EAA with 120 and C8a humble it.


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Well, here's one stack 52 x 8s = 412s I took with the lightweight Photoline Apo 60/360 at about F/4.7 with a ASI 224 last weekend:

 

 

Stack_52frames_416s.jpg

 

 

It should be possible to see at least as much with an 80mm refractor, I guess.


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#12 NaNuu

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Posted 25 May 2018 - 04:05 AM

I use a Skywatcher Doublet ED 80 called "Photoline". It's a f7 .

Just take a look in my recent EAA posts and you will see what's possible and whats not.

 

attachicon.gif IMG_5894.JPG

That's not Skywatcher, but TS-Optics, isn't it? (-;


Edited by NaNuu, 25 May 2018 - 06:07 AM.


#13 Mark Brickley

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Posted 25 May 2018 - 05:43 AM

 
 

I would wholeheartedly reccomend the explore scientific ed80 carbon fibre. 

 

I have used a few different refractors including a wonderful televue 101 and 127is and I would say, especially for the money, and taking aperture into account the es80 cf gives a good account of itself. It is also collimatable which I found to be very useful when I dropped it and knocked out the collimation. It is light at less than 2.5kg and runs beautifully on my smart EQ Pro which is a mount in the similar range to your proposed one, albeit equatorial. The focusser is good to excellent and it comes well packed in a hard case

 

I am  using it very well for EAA use and it travels well in hand luggage. 

 

Attached are the diffraction patterns of an artificial star of the scope collimated. These show an excellent set of optics and my visual impressions coincide with this.

 

I would say after that glowing review that I have no connection at all with es, I am just very happy with this scope

 

all the best 

Mark

 
3d analysis.png
 
star pattern.png
 
M81 S0002 V

 

 

 


Edited by Mark Brickley, 25 May 2018 - 05:48 AM.

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#14 Mark Brickley

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Posted 25 May 2018 - 05:52 AM

Nonsense. I can detect galaxies galore on my 80mm F/6.

+1

I’m getting good EAA and short duration images of lots of galaxies very easily with my 80mm scope and in fact prefer it to my c8 because there’s less faffing around with focal reducers and the like. The main issue with small galaxies is one of image scale with a relatively short Fl refractor and the new 183 or 178 class cameras with tiny pixels address this.


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#15 Stargazer3236

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Posted 25 May 2018 - 07:02 AM

Try the Barska Magnus 80mm Triplet: Apochromatic triplet lens configuration further corrects chromatic aberration, Two convex FK61 ED crown glass lenses and One concave H-LaF2 flint glass lens.

 

There is a forum on here that touts how good this scope really is. https://www.cloudyni...-barska-magnus/

 

It is only $439 complete with hard carrying case, dovetail, 10mm EP, 8-24mm zoom EP, 2" 99% dielectric diagonal, 80mm F/7 optical system. There is one caveat...the focuser is not the best and most CNers that bought one just replaced it with one from GSO.

 

I plan on buying one in a month or so.



#16 Destrehan Dave

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Posted 25 May 2018 - 07:09 AM

I would wholeheartedly reccomend the explore scientific ed80 carbon fibre.

I have used a few different refractors including a wonderful televue 101 and 127is and I would say, especially for the money, and taking aperture into account the es80 cf gives a good account of itself. It is also collimatable which I found to be very useful when I dropped it and knocked out the collimation. It is light at less than 2.5kg and runs beautifully on my smart EQ Pro which is a mount in the similar range to your proposed one, albeit equatorial. The focusser is good to excellent and it comes well packed in a hard case

I am using it very well for EAA use and it travels well in hand luggage.

Attached are the diffraction patterns of an artificial star of the scope collimated. These show an excellent set of optics and my visual impressions coincide with this.

I would say after that glowing review that I have no connection at all with es, I am just very happy with this scope

all the best
Mark

Very nice image... may I please ask the number of exposures and duration of that particular galaxy?

I’m going to guess you were at a nice dark site?



Thanks

DD


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Edited by Destrehan Dave, 25 May 2018 - 07:39 AM.


#17 Destrehan Dave

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Posted 25 May 2018 - 07:25 AM

Well, here's one stack 52 x 8s = 412s I took with the lightweight Photoline Apo 60/360 at about F/4.7 with a ASI 224 last weekend:


attachicon.gif Stack_52frames_416s.jpg

It should be possible to see at least as much with an 80mm refractor, I guess.


Very Nice image!
What capture software did you use?
Did you do any post-processing?
Was it a nice dark site?

I know that galaxies are really tough unless you have some good dark skies and decent seeing.

To clarify what I meant, the classic concept of EAA (to me) means live view, often in rather poor, city or suburban conditions. I know that I have seen NGC 891 pop out in a live view C8, and was nowhere to be found under similar live view with a smaller aperature refractor.

If I want to take 5 or 10 minutes of lights and spend time doing deepskystacker, photoshop and/or pixinsight, to me that’s a secondary (and very nice, BTW!) benefit of EAA. I’m going to try the 50 or 75 short exposure / deepsky stacker thing next time and see if I can reproduce your results.

I guess it depends on whether you want to do EAA imaging or live view. Yours, and the other images posted on this thread prove that you can indeed produce nice images with a small refractor...

But if you are talking about ‘live view’ I still maintain C8 with reducers is the way to go..

DD


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Edited by Destrehan Dave, 25 May 2018 - 07:44 AM.

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#18 mega256

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Posted 25 May 2018 - 11:23 AM

Go with a 80mm F6-F7 triplet.....much better in the long run!! Optics planet has them with a 13% off today TEIE13 for $426.....(Barska Magnus 80mm Triplet)... .hard to beat..
The 80mm F6 triplet is a great EAA scope..with the infinity camera get a reducer to get in the F4-5 range,for a little faster image....good combo. It is a EAZY/PEAZY setup.
I use Astro-Tech AT80EDT f/6 ED Triplet Refractor OTA..but its more money...but very nice for EAA.
I do find that a triplet for color eaa cameras does a good job.

To look at mine..80mm/infinity

https://www.youtube....eature=youtu.be


Bob

Edited by mega256, 25 May 2018 - 12:39 PM.

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#19 Don W

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Posted 25 May 2018 - 02:30 PM

Orion ED80, Vixen ED80Sf and several others by Celestron and a couple other companies use the same lens. The tube and focuser are different.



#20 NaNuu

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Posted 26 May 2018 - 03:04 AM

Very Nice image!
What capture software did you use?
Did you do any post-processing?
Was it a nice dark site?

I know that galaxies are really tough unless you have some good dark skies and decent seeing.

To clarify what I meant, the classic concept of EAA (to me) means live view, often in rather poor, city or suburban conditions. I know that I have seen NGC 891 pop out in a live view C8, and was nowhere to be found under similar live view with a smaller aperature refractor.

If I want to take 5 or 10 minutes of lights and spend time doing deepskystacker, photoshop and/or pixinsight, to me that’s a secondary (and very nice, BTW!) benefit of EAA. I’m going to try the 50 or 75 short exposure / deepsky stacker thing next time and see if I can reproduce your results.

I guess it depends on whether you want to do EAA imaging or live view. Yours, and the other images posted on this thread prove that you can indeed produce nice images with a small refractor...

But if you are talking about ‘live view’ I still maintain C8 with reducers is the way to go..

DD


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Thank you!

 

I used SharpCap 3.1 with dark subtraction (20 dark frames, if I remember right) - not exactly a dark side: city balcony, sort of red LP. No filters, though (I used to use a Baader uhc-s filter, but its 1.25" and doesn't fit with the 2" reducer...) - there's no AP kind of post processing for that stack here, it's been 'saved as viewed' and converted to jpeg, maybe some file size reduction by jpeg compression, I can't remember. There are better stacks from that night, but they took quite longer total integration times... It's my kind of EAA fun, I like to sit and stare at one single object for half an hour or even longer. (-; 

 

Of course! You will almost for sure get more details within shorter integration times if you use a C8 with good reducers- but you need more over all weight to do so (the whole setup with scope, mount plus cam can be about the C8 OTA's weight). (-; Even my 6SE leads to better (or quicker) pictures, but I just love the wide FOV and lightweight little setup with the little scope and time is not a major problem to me. Lbnl: the topic starter asked for such setup's capabilities, therefor....



#21 Stargazer3236

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Posted 26 May 2018 - 06:54 AM

I took this image with my AT60ED refractor using an ASI385MC camera.

Attached Thumbnails

  • m51-350g-1x1b-12x8s.jpg
  • ngc4565-full-frame_orig.jpg
  • leo-trio-2x2b-350g-7m-45s.jpg

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#22 Destrehan Dave

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Posted 26 May 2018 - 07:23 AM

I took this image with my AT60ED refractor using an ASI385MC camera.


Very impressive. Thanks for posting.

How dark was the site?

Did you use any filters or do any post-processing?

DD


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#23 Stargazer3236

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Posted 26 May 2018 - 11:04 AM

No filters, no post processing, and the dark site was not very dark. I can see better with my camera, than I can see with my eye visually. Light pollution is rampant in my neck of the woods.



#24 DSO_Viewer

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Posted 26 May 2018 - 12:40 PM

No filters, no post processing, and the dark site was not very dark. I can see better with my camera, than I can see with my eye visually. Light pollution is rampant in my neck of the woods.

You will always see better with a camera than with the human eye visuallywink.gif


Edited by DSO_Viewer, 26 May 2018 - 12:41 PM.


#25 Mark Brickley

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Posted 28 May 2018 - 01:51 AM

Very nice image... may I please ask the number of exposures and duration of that particular galaxy?

I’m going to guess you were at a nice dark site?



Thanks

DD


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Hi Dave 

 

thanks i I appreciate it.

 

I’ve put the full details in the thread M81 with es80 but I’m very pleased with this setup,this was 14 minutes of 20s subs as  I recall. Please note this linked image is processed as I outline exactly in the other thread where I’ve also included a raw screen grab but actually there was little difference between the two.

 

It’s taken from my back garden which has pretty good skies but some local light pollution.

 

all the best 

mark 




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