I'm undecided as to what I should purchase next...

[ramdom]

Hi all, I'm really undecided about my next telescope purchase - I can spend about $10K easily and can go up to $20K if it would be worth doing (though ideally I'd like to get both a refractor and reflector over a span of a year or two). My choices for OTAs are the Astro-Tech AT65ED, Takahashi FSQ106, Explore Scientific ED152 triplet carbon fibre apo, AT 130 EDT. For mounts, CGX, CGX-L, AT Mach1, and for reflectors, the Obssession 18-22" scopes. My uses are both visual and taking the fastest images with the least amount of time (closer to video astronomy than to hardcore imaging).  Right now I'm thinking low res video (Lodestar/Ultrastar cameras) but in the longer term, something like hooking up a Sony A7s wouldn't be out of the question.

The reason I was thinking of the AT65ED first is because it seems to be what I want (an astrograph that can do visual---if any of the bigger RASAs could do that I'd probably go for that) but if I don't like it, it wouldn't put me out too much in terms of cost. If I do like it, I could get the Takahasi FSQ106 and have both.

I really get that once you get into imaging/video, each scope is like a lens and having different ones gives you different perspectives, but would the perspective of an AT65ED be different enough from that of a Takahashi FSQ106 (there's a used version from OPT on sale for about $4,300) that both are worth getting?

Continuing with refractors, the other option suggested was to get an AT 130 EDT or the the ES ED152 triplet CF but these tend to have slightly longer focal lengths (F7) and it's unclear why I'd prefer the 130AT over the ES152, aside from price. Also it's unclear if I can hook up a focal reducer that will get me the views that the Takahashi could (i.e., get a F3 system even though it ends up being pricey). If money weren't an issue, would all of you who own the Obssession 18-22" and larger SCTs say that the Takahashi is worth it (for both visual and imaging)?

I could try sticking the Lodestar in my Meade ETX80 and seeing what it looks like, especially with the black and white camera.

As far as mounts, is there that much of a difference between something like the CGX-L and the AT Mach1?  I'm comfortable with Celestron technology and I'm wondering about things like StarSense, etc. That ability that StarSense provides is very useful to me given that time is my biggest issue.

The Obsession of course would be going the other way and both directions (refractor/reflector) is somehing I intend to explore but the question is which way to go first, and which path offers me the least risk in case I don't like it and lets me get to observations while spending the least amount of time figuring out gear, etc. I do have space to store the Obssession (either my garage or my studio where I currently keep my scopes). But I am worried about managing a reflector in terms of collimation, etc. Also, unless I get a good wedge for the reflector, I will be limited to short exposures (which is what I do now anyway and a larger aperture scope may be okay for this). But even here, I'm going vacillating betwee the 18-22" UC designs. I think the 18" UC may be the safer choice (in terms of weight, etc.) and if I really get into reflectors one day I can get the 25" one. So even though once I say "reflector", the choice about which refractor to buy is eliminated, the choice of which aperture to get is unclear.

In the end of it all I might come back and say that the C9.25" I've been using (but whose correct plate is broken when it fell down due to wind) was the best way to go.  So I will get it fixed and it will be a part of my collection. But I also think a quality refractor and a quality reflector would be welcome additions and I can get one of these this year. I'm tempted to pull the gun on the used Takahashi, along with the reducer (perhaps I can get one used as well, but even a new one would be under my budget of $10K this year).

--Ram

PS: For the first time since the accident that broke the corrector plate in my C9.25", I turned on my mount and tested its motors and it seems to be fine (though it still sounds like a coffee grinder at times). So only the OTA needs to be replaced, worst case.

[N3ptune]

I can't help you with the telescopes but your website is really interesting!

[nightfisher]

My advice would be to get a large dobsonian, if your skies are good i would look at the 18" and start enjoying the night sky while deciding on the imaging rig

[ramdom]

N3ptune and nightfisher, thanks.

nightfisher,  I'm curious as to any specific reasons you'd recommend the 18" ($7649) instead of the 20" ($7995)?  I think the 18" would be more manageable, but at f/4.2, a parcorr coma corrector ($495) is highly recommended, and with that, the price is more than what it would be the 20" (classic version) which doesn't need the coma corrector.  

That said, with the 18", most my observation can be done while on the ground (5'11" eyepiece height at zenith) whereas I'll require a ladder for the 20" (8' eyepiece height at zenith).  For people who own these types of large scopes that use a ladder/stool to, how much of an inconvenience is it?  I'll be using it with the GoTo system.

My location is in a rural area, so there's little light pollution but between the cold and the clouds, I probably can't observe that much in the winter. If I get this scope, then I can put it in my garage and wheel it around my home as needed and if I really need to transport it, I have an SUV that it should fit in. They also offer ultra compact versions of these scopes that are more portable with some tradeoffs, but the 18" UC is $6995 and the 22" UC is $10,495.

--Ram

 

[niallk]

Perhaps you have read up (on Cloudy Nights in particular) - it would seem that the 15" and 22" UC hold collimation better than the 18" UC.

If you have dark skies and observe from home, the 20" f/4 Classic is the one I'd look hard at... OR something like this on the used market - including Teeter/Webster etc.  I think the 22" UC generally gets very positive reviews if you are set on a compact scope.

Best of luck with your decision!

[timwetherell]

Depending on your circumstances, it may be worth setting aside a small proportion of your budget for an observatory of some description to house these instruments in. Rapid and easy deployment of a telescope greatly increases one's opportunities to observe. In the UK where our weather seems to change every few minutes, it's enabled me to catch windows of clarity I would have otherwise have missed. Also if you're getting into the realm of really big Newtonians, it would be nice to have the scope in more or less permanent thermal equilibrium with the environment.

 

[nightfisher]

I would look to the used market for a decent Dobsonan, and if you think you wll be transporting in the SUV, get a collapsible truss design, one of our members on here (Mapster) built his own 22" F3.8 and it fits in an Audi estate car, takes 25 minutes to assemble plus cost a lot less, i dont know that i would want goto on a large dob, put the goto cash into high quality optics 

[Jessun]

Hi!

I'll leave visual work to others as I know nothing about it.

For imaging, the scopes you list are all very different.

Looking at imaging, I'd start out with working out your seeing and then look for a camera/OTA combo delivers close to that number. You mentioned the Sony A7 and again I know nothing about this one, but I can quickly Google a pixel size of 5.96 or 4.87 microns - correct me if I'm wrong. Those are good numbers, middle of the field really and lends itself to many scopes.

Then download this tool or similar:

http://www.newastro.com/book_new/camera_app.html

In there you can play around with cameras and scopes etc, and you can put in the Sony details, and then change the focal length to match your seeing. Let's say you settle for something like 600mm to 900mm. Well, then the next question is how fast you want to image. Keeping the focal length fixed, as you open the aperture the faster the exposures. Money disappears almost exponentially as f-ration goes down... And so do all other problems with focus and collimation etc...

The other parameter that plays a huge part in imaging is of course CCD/CMOS chip size but with the Sony you will enjoy quite the field already.

Back to the Sony, again I know nothing about it, but I have seen quite a few threads about it on SGL. Perhaps there are other cams that can compete.

/Jessun

 

 

[N3ptune]

I am no specialist in dobsonians but what about the the Skywatcher 16 inches dob F4.4? It has Synscan and it's collapsible, takes less space, maybe easier to move around and faster to set up then other brands, good looking.  I understand it may not be the highest quality of optics compare to artisanal but everything about It seems to be intelligent. Also, it's not too high, a small step could do the trick.

http://ca.skywatcher.com/product/product/bk-dob-16-synscan-gps/

https://www.youtube.com/watch?v=MlR0IPSoDdE

[kirkster501]

On 22/04/2017 at 07:47, timwetherell said:

Depending on your circumstances, it may be worth setting aside a small proportion of your budget for an observatory of some description to house these instruments in. Rapid and easy deployment of a telescope greatly increases one's opportunities to observe. In the UK where our weather seems to change every few minutes, it's enabled me to catch windows of clarity I would have otherwise have missed. Also if you're getting into the realm of really big Newtonians, it would be nice to have the scope in more or less permanent thermal equilibrium with the environment.

 

^^^^I could not agree more.  I really, really, REALLY advise the OP to take this into account. 

The oldest cliche is amateur astronomy, and the most true, is "The best telescope is the one you use".  The size of Dob scopes rapidly increases in size.  I was gobsmacked at the difference in size and weight when I went from a 8 inch Dob to a 12 inch - the thing is a monster.  These simple truths are so easily forgotten in the excitement of contemplating a new purchase and whilst all this talk of huge scopes is great, after the initial  enthusiasm it can rapidly become a PITA to keep setting up and tearing down to the extent that some nights after work you just can't be bothered lugging that huge scope out of the garage.  Many of us on this forum will tell you this.  That's why large binoculars and cheap 8 inch Dobs are so popular.

[estwing]

8 hours ago, kirkster501 said:

The best telescope is the one you use".

So go get a 28" Webster then that will be the one you will use

[timwetherell]

A friend of mine has a 24" newtonian in a permanent observatory and it's a fabulous instrument . But he lives at a dark site with lost of land. If he had to pack it down into the back of a truck and drive twenty miles to set it up in a damp field, I suspect it would have quite a few cobwebs on it by now  

Another thing to consider is field of view. With a 31 Nagler, my 7" yields just a hair over 2° and looking back through the sketches in my notebooks, that's my most used eyepiece on deep sky stuff. A 24" f4 Newtonian can only manage a 1° Fov, and a 16" SCT is going to be closer to half a degree. If you could balance it, that 28" Websrer with a 6" apo finder would be an awesome do-all combination! Though balancing the cheque book afterwards may not be so easy  

[estwing]

1 hour ago, timwetherell said:

A friend of mine has a 24" newtonian in a permanent observatory and it's a fabulous instrument . But he lives at a dark site with lost of land. If he had to pack it down into the back of a truck and drive twenty miles to set it up in a damp field, I suspect it would have quite a few cobwebs on it by now  

Another thing to consider is field of view. With a 31 Nagler, my 7" yields just a hair over 2° and looking back through the sketches in my notebooks, that's my most used eyepiece on deep sky stuff. A 24" f4 Newtonian can only manage a 1° Fov, and a 16" SCT is going to be closer to half a degree. If you could balance it, that 28" Websrer with a 6" apo finder would be an awesome do-all combination! Though balancing the cheque book afterwards may not be so easy  

It would gather cobwebs due to lack motivation and effort that's not the scopes fault,but the owners 

[timwetherell]

7 minutes ago, estwing said:

It would gather cobwebs due to lack motivation and effort that's not the scopes fault,but the owners 

For sure, it won't take itself out  But at the end of the day amateur astronomy is a fun hobby not a "duty". To some moving a big scope to a dark site is rewarding - and more power to em! But for others work and family pressures, physical fitness and general "life exhaustion" may mean a smaller instrument will be used more often. I used to have a very large refractor and it was an awesome instrument but to be completely honest I used it lass than the smaller scope I had before, because it took so much time and effort to set up. A "quick look" at anything was out of the question. 

I'm not meaning to put down large portable scopes in any way, they're a great choice for some people and a big scope at a dark site will always give far better views than a small one at a mediocre site. But I think it's horses for courses and convenience is an important factor in choosing the right telescope for each individual. If resources allow, a big portable and a small grab and go are probably a winning combination!