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What Telescope Should I Buy?

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#1 satellitespotter

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Posted 20 March 2019 - 03:53 AM

Hi everyone,

I've had my Celestron 6se for a while now and I am thinking of upgrading. I have a budget of up to $2000 USD. I am leaning towards an 8" Celestron Advanced VX SCT or possibly the 9.25" version, but I was wondering if I should go for something else like an Explore Scientific 127 mm Triplet ED APO Carbon Fiber Refractor. I am interested in both deep sky and planetary imaging. If anybody has any suggestions that would great!

Thanks, Nick



#2 OleCuss

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Posted 20 March 2019 - 05:08 AM

First, I'd generally recommend not trying to do both planetary and DSO imaging with the same gear.  It can be done, but especially if you are a beginner it will be a challenge you may not enjoy.  The equipment choices and technique tend to be at different parts of the AP spectrum.

 

If you want to do good imaging with an SCT, you get one of the CSCTs (Corrected SCT) like the EdgeHD and that means that even with the 8" on an AVX your budget is blown.

 

For imaging DSOs?  Unless you are expert, have really good equipment, and really want/need to go for the really deep and dim DSOs you should really consider keeping the focal length to less than 700mm and even shorter focal lengths make it easier/better.

 

The 8" CSCT will have a native focal length of about 2 meters.  That's not bad for planetary but it will be difficult for DSOs because we generally don't like doing lucky imaging on DSOs and the tracking and "seeing" problems get much worse with that kind of focal length.  You can get the focal length down to about 800mm when Starizona starts selling their 0.4x reducer, but you'll still be in the challenging/frustrating range of focal lengths - and doing it with an AVX mount which some find to be merely marginal to inadequate.  It can be done, but it might be considered to be masochism.

 

Those carbon fiber refractors are sometimes lighter than the alternative but that is the only benefit from the carbon fiber.  They were touted as reducing the need to re-focus but the reality is that increases the need to re-focus and cool-down is slower.  You'll note that the premium telescope makers generally do not use the carbon-fiber for their OTAs even though their buyers tend to be the ones who would demand it if it were superior.

 

The "ED" series from Explore Scientific are, I think, the FCD1 series.  Not really an apochromat when you are doing imaging.  Very nice for visual use but a great way to decrease the quality of your images!

 

If you want to go with an FCD1 I'd recommend taking a deep breath, back away from the keyboard for a few minutes, and re-consider.  An Ed-Doublet would probably give you optics about as good as the FCD1 and will do it with lighter weight and better cool-down - and maybe at lower cost.

 

The 127mm Explore Scientific has a 952mm focal length (which makes imaging more difficult/frustrating) and is too heavy for your AVX mount idea.

 

Now if you were to get the Explore Scientific 80mm FCD100?:  https://explorescien...0-apo-refractor  Nice short focal length for easier imaging, lighter weight, faster cool-down, and less cost - with better optics.

 

If you went for their 102mm FCD100 you are getting into a more challenging focal length but otherwise it should perform fairly well.

 

I don't think Explore Scientific sells a matched field flattener and over time I've come to the opinion that I'm just not buying a rather expensive triplet (or even ED-Doublet) refractor for imaging purposes unless I can also buy a field flattener which is sold by the manufacturer and matched to that particular OTA.  I don't mean just "recommended" I mean matched.  Unless it is truly matched to that particular OTA I don't trust it to do the job to the degree that I demand if I'm trying for that degree of optical excellence.

 

But a quite different suggestion?

 

If you are a beginner at imaging and you want fast imaging at a reasonable cost?  Get the AVX mount and then get the Astronomics 6" astrograph:  https://www.astronom...tical-tube.html  You'll get more aperture for faster imaging, the weight is pretty nice, and the price is very good.  Yes, 6" means a bit of a cool-down time period but it shouldn't be very long.

 

Then you also get a good coma corrector and you are pretty much set.

 

The savings means that if you want to autoguide you have some money left over to make that happen.  I still refuse to autoguide and I don't suffer much as a result - and I'm not trying to compete with the folk who do autoguide so I'm far happier not doing that.

 

 

OK, one other thing?  We really ought to know what camera you plan to use.  That might change things a fair bit.

 

 

Now if your emphasis is on trying to do high-quality imaging?  Getting the big SCT and a camera which will do video at a rather high frame rate is usually the ticket.  A CSCT is nice but not particularly necessary since you'll probably be centering the planet you are imaging so the regular SCT focusing issues and coma/curvature issues are not likely to be a concern.


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#3 satellitespotter

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Posted 20 March 2019 - 05:16 AM

Hi OleCuss,

Thanks for the suggestions, I already have an asi224mc, which is a high frame rate camera that I attach to my current SCT. Concerning the VX mount, should I go for a different mount/telescope that would track better?

Thanks, Nick



#4 OleCuss

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Posted 20 March 2019 - 06:27 AM

Better is always better, but you have to look at cost, transportability, etc.

 

If you are planning to use the ASI224. . .  When used with an SCT you are going to have a tiny FOV.  Add a Barlow to the SCT, fire up the ASI224 and you can do some pretty decent planetary AP.

 

But with the ASI224 in combination with something like an 8" SCT?  That tiny FOV is going to make it hard to even find your target and a bunch of nebulae simply won't fit onto your sensor.

 

Again, you can do stuff, but it seems rather unlikely that you are going to be as happy as if you did it differently.


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#5 JOEinCO

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Posted 20 March 2019 - 06:41 AM

Awful lot of imaging details in the forum that specifically says "No Astrophotography Here"....


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#6 satellitespotter

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Posted 20 March 2019 - 06:45 AM

Hi Joe,

Yeah, but it wasn't an astrophotography related question, it just came up in the conversation. There isn't really a better section that I know of that would fit this question. 

Thanks, Nick



#7 JOEinCO

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Posted 20 March 2019 - 07:14 AM

...... I am interested in both deep sky and planetary imaging. If anybody has any suggestions that would great!

I guess I was confused by what you wrote, and the only reference to how you would use the scope.

 

Guess I'm confused. Need more coffee! grin.gif 



#8 OleCuss

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Posted 20 March 2019 - 08:07 AM

Yeah, I'd rather expect this thread to get moved when a moderator comes across it.



#9 Starman27

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Posted 20 March 2019 - 09:18 AM

Please keep the discussion to his question about the choice of telescopes constrained by an interest in astrophotography not a how to do astrophotography.. This is not an astrophotography forum so let's keep the responses focused on the telescope choice.



#10 merlin5353

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Posted 20 March 2019 - 03:43 PM

Hi everyone,
I've had my Celestron 6se for a while now and I am thinking of upgrading. I have a budget of up to $2000 USD. I am leaning towards an 8" Celestron Advanced VX SCT or possibly the 9.25" version, but I was wondering if I should go for something else like an Explore Scientific 127 mm Triplet ED APO Carbon Fiber Refractor. I am interested in both deep sky and planetary imaging. If anybody has any suggestions that would great!
Thanks, Nick

Nick, I'm a newbie, so i have to ask, what limitations or difficulties have you experienced with your 6se? I recently got (my first ever) a C8 SCT with an AVX mount for looking at shtuff. I haven't seriously considered AP with it (so far). Have you done AP with your 6se? John

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#11 N3p

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Posted 20 March 2019 - 04:23 PM

I found these quotes somewhere and kept them to add to my non existant signature.

 

#1. Get the best optics that you can reasonably afford.

#2. A good observer can see more with a basic scope than a poor observer with a premium scope. (Perhaps irrelevant here but cool to copy/paste anyway) 

 

Wise words from unknown users, perhaps CN users, can't say.


Edited by N3p, 20 March 2019 - 04:24 PM.


#12 Starman27

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Posted 21 March 2019 - 10:39 AM

Looks like your decision is between an SCT and refractor. Both of the scopes you mentioned are fine examples, but different in the way they interact with you.  I have a Meade 8 f6.8 inch SCT and a f8.8 TAK FS128 NSV. The SCT is used for outreach and star parties and is a wonderful scope. It rides on an Ioptron CEM25. The 128mm refractor (observatory mounted) requires a much larger and more stable mount because of it's momentum.  Carbon fiber will reduce some weight. I think you may find the SCT more flexible. The ES refractor is fine but requires solid mount. Both I think haves issues with tear down and set up. The views will be similar. Since you have a good SCT you may want to try out a refractor. But, I would recommend a smaller one 80-100mm. Also, if you have an astronomy club near by try out different scopes and check out the relative image quality (using your own eyepieces). Also, watch how they set up and tear down and pack the scopes for travel.



#13 gnowellsct

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Posted 21 March 2019 - 02:22 PM

Hi everyone,

I've had my Celestron 6se for a while now and I am thinking of upgrading. I have a budget of up to $2000 USD. I am leaning towards an 8" Celestron Advanced VX SCT or possibly the 9.25" version, but I was wondering if I should go for something else like an Explore Scientific 127 mm Triplet ED APO Carbon Fiber Refractor. I am interested in both deep sky and planetary imaging. If anybody has any suggestions that would great!

Thanks, Nick

 

 

If you MUST have go-to:  

 

I would get the used AVX mount and tripod on Astromart for $650 and a used c8 or 9.25 which are also on Astromart.  Enjoy the views with eyepieces and do some moon imaging with a web cam, you'll have enough money left over this way that you can buy some accessories.  

 

The refractor should come later in my opinion, whether for imaging or visual.  The eventual entry level refractor should be a Skywatcher or perhaps an Orion ED80.  After some time with the AVX you'll have a better sense of what mounts do, and don't do, in this price tier.  

 

Even better would be a Great Polaris or Super Polaris with no go to.  That is, a good quality mount that will hold a c8 or a 4 inch refractor while learning the basics of telescopes and the sky.

It's getting harder to find a non-go-to mount these days.  Everyone wants to sell a cheap mount that stalls and breaks and keeps your nose on the paddle worrying about this or that when your eyes should be on the sky.

 

Truth be told I would not get the used AVX mount but it is difficult to break the news to beginners what good equipment costs.  I know I didn't want to hear it, twenty years ago.  

 

Greg N


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#14 spaceoddity

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Posted 21 March 2019 - 03:21 PM

If you MUST have go-to:  

 

I would get the used AVX mount and tripod on Astromart for $650 and a used c8 or 9.25 which are also on Astromart.  Enjoy the views with eyepieces and do some moon imaging with a web cam, you'll have enough money left over this way that you can buy some accessories.  

 

The refractor should come later in my opinion, whether for imaging or visual.  The eventual entry level refractor should be a Skywatcher or perhaps an Orion ED80.  After some time with the AVX you'll have a better sense of what mounts do, and don't do, in this price tier.  

 

Even better would be a Great Polaris or Super Polaris with no go to.  That is, a good quality mount that will hold a c8 or a 4 inch refractor while learning the basics of telescopes and the sky.

It's getting harder to find a non-go-to mount these days.  Everyone wants to sell a cheap mount that stalls and breaks and keeps your nose on the paddle worrying about this or that when your eyes should be on the sky.

 

Truth be told I would not get the used AVX mount but it is difficult to break the news to beginners what good equipment costs.  I know I didn't want to hear it, twenty years ago.  

 

Greg N

You can still get a new AVX for $699. As long as they are still available at that price, I wouldn't pay more than $500 for a used one. 


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#15 Maverick199

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Posted 23 March 2019 - 05:53 AM

Guess I wanted to say what Greg N and Spaceoddity mentioned. 



#16 MalVeauX

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Posted 23 March 2019 - 07:27 AM

Hi everyone,

I've had my Celestron 6se for a while now and I am thinking of upgrading. I have a budget of up to $2000 USD. I am leaning towards an 8" Celestron Advanced VX SCT or possibly the 9.25" version, but I was wondering if I should go for something else like an Explore Scientific 127 mm Triplet ED APO Carbon Fiber Refractor. I am interested in both deep sky and planetary imaging. If anybody has any suggestions that would great!

Thanks, Nick

Hi Nick,

 

If your budget is $2k, you have a C6, and you need a mount to track to image, the simple answer is: put your budget into your new mount.

 

An AVX is an inexpensive mount that will get things started, but you will not like using it for long exposure still photography (DSO) with a larger instrument with a long focal length (like that big 127mm tripliet APO you're referring to). It will handle a larger instrument for video photography, such as for planets, lunar, etc. So if you go with an AVX, or similar, you will want a much smaller instrument (60~80mm, F6~F7) for long exposure (DSO) imaging and you can get something more like an 8 inch (C8) for planets and lunar, etc, and that will work ok.

 

But, if you really enjoy this and you're prone to get more scopes, try new things, image lots of different subjects, you'll quickly out grow and out class the AVX.

 

I really suggest you put your budget into something else, like a SkyWatcher EQ6 or Atlas (same mount), or iOptron ieq45 (or upcoming CEM40), or Celestron CGEM II, etc, basically looking at the Chinese 40lb mounts. It's not all about the weight, it's also the tracking guts you'll want.

 

Then save up, and add appropriate scopes to your line up. You can image with a lot less expensive scopes. You can't image with a lot less expensive mounts with big scopes.

 

Very best,




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