Telescope for AP purpose only

[Orichae]

Hi there,

I am on the lookout for a new telescope for AP only and hope to get some advice here.

So far, I’ve narrowed down my list to either a 10 or 12-inch reflector (looked at several brands) or go with a Celestron RASA.
I’m not concerned with collimation or total required budget (incl. mount and accessories) and struggle to figure out other relevant pro’s and cons between these two options.

For visual I intend to get hold of a separate telescope and mount so I would not be using a reflector for visual purposes nor would I be able to do so with the RASA.

Any thoughts or recommendations on the above would be appreciated.

Thank you kindly.

[alanjgreen]

Hi Orichae,

Can you tell us why you have gone for such large aperture? Aperture is not important for AP. A 10 or 12 inch reflector sounds like a great VISUAL scope.

Are you new to all this? What scopes have you used for AP in the past?

Can you tell us what MOUNT you have or are planning to buy? THE MOUNT IS THE MOST IMPORTANT THING IN AP!

If you are a newbie, then I suggest you pause and reflect on a much simpler alternative such as a 80ED refractor as a starting AP scope. That huge reflector will be WIND AFFECTED as its as big as a sail!

Do you already have a camera or you will be buying one later?

But most of all, I recommend that you buy the book "Making every photon count" and read it BEFORE spending your hard earned cash

Here is the link

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Hope none of this caused any offence

Alan

[Orichae]

Hi Alan,

Appreciate your response and no offense taken at all

Yes, I consider myself to be a newbie.
Even though I read the book make every photon count last year and spent a year reading up on this forum and other sources there is still so much I need to figure out and learn.
Still need to learn a lot however I intent to take my time with learning AP (1 to 3 years) and am actually looking for a challenge so not expecting to make great shots out of the box nor am I scared off by complexity.
A 10 or 12 inch Newtonian reflector is on my list as light bucket but then i stumbled upon the RASA.

I intent to use my Nikon DSLR D810 at first and might move towards CCD's at a much later stage.

I understand that the mount is the most important aspect and did not included this in my post as the choice between a Newtonian or RASA (or third option as you mentioned) impacts the choice of the mount for me.
budget is not a concern at all so i consider myself fortunate to be able to not let that weigh down any options.

Kind regards,

[happy-kat]

Welcome to SGL

Do you see in your plan building an obsy?

Have you looked at images you like and seen what equipment was used? 

[vlaiv]

Contrary to stated above, I do believe aperture is important in AP if coupled with everything else in the right way.

If you are set on reflector of large aperture (and budget is not concern), my personal choice would be either RC, or Riccardi-Honders Astrograph, depending on sensor I'm planing to couple it with. Also choice of targets would somewhat dictate choice of optics.

But I do agree that mount should be your first choice, so don't choose scope first, first choose mount you are willing to work with and spend money on. Next decide on resolution you are going to be working at (or multiple resolutions, meaning different scope / camera combinations - all of which will be limited by mount so make your first choice wisely) - your imaging location is going to have an impact on this one. Consider seeing throughout the year and what will be realistically achievable resolution most of the time. Once you decide on resolution you need to look at OTA + camera combinations rather than OTA on its own. Look for OTA that gives you largest aperture and cleanest and largest field for that resolution. 

 

 

[Orichae]

I never considered an obsy before and do not envision having/building or planning for one.

In terms of the mount suggestions, I would love to be able to use a heavy duty mount that will not require upgrading anytime soon and since i have been considering the RASA, the CGX-L looks like a good fit.
for Newtonians/Astrographs, i've been looking at different brands yet lack sufficient understanding / reasoning if I am better off with this route as opposed to the RASA.

Location is in a light polluted area with occasional travel to darker sites in the Netherlands (heavy mount/scope is not a concern for me personally)

[Stu]

@Orichae do you have an understanding of the targets you want to image and the camera you intend to use? That would be helpful for people to know when advising you.

[vlaiv]

Ok, lets look at this "the other way around".

So you will be using Nikon D810 as your weapon of choice. That camera has 4.88um pixel size. You are also planing to get mount in CGX-L class. So in general I would put a limit to your imaging resolution of around 1.5" - 2.0" /pixel to have a safe margin with respect to guiding and all. Most of CCDs that you are likely to get later will have similar pixel size, so we need to check which focal length will suit you better Celestron RASA with 620mm or Newtonian with around 1000mm focal length.

With this pixel size, go with Celestron RASA, it will give you manageable resolution of 1.62"/pixel. 10 or 12" newtonian will be seriously pushing it with resolutions close to 1".

There are couple of other things to consider with RASA - camera is mounted in front of objective, so you really want small / round camera body not to get into light path, and there is issue of cable management ...

[Orichae]

@Stu: My favourite objects and aspirations are Nebulea, Galaxies, I intent to start with my Nikon D810 however might move onto CCD at a much later stage.
@Vlaiv: Thank you for the advice, I'm leaning towards the RASA now.

Since I am a beginner/newbie I am not too concerned about the camera placement of a somewhat bulky DSLR in front of the objective or "curving" the cable in terms of cable management.
Once i'm ready for a smaller, rounded CCD i can always upgrade.

One more question, would it be feasible to stack a separate telescope at a later stage on top of the RASA for visual purposes only provided I do not exceed the weight limit of the mount?
Or is this out of the question and would this require swapping scopes depending on use?

[Stu]

The 11" RASA sounds an amazing scope. It also sounds quite a beast and I suspect one that might get a bit much of you are setting up and breaking down each time. Mounting a 20kg scope is something to be done carefully, I know, I've owned one.

Have you seen one in the flesh? Well worth checking out before you commit.

[Orichae]

I've seen similar-sized scopes at local events over the past year so do feel comfortable with the size in terms of what I have seen although have no experience in setting up and breaking down taking weight into consideration.
If need be I can always count on an extra pair of hands fortunately. Personally don't feel the need to see one in the flesh before I decide to commit but that's just me.

 

[mark81]

I'm all new to visual astronomy but i have been watching a guy on youtube called astrobackyard, he gets amazing AP images using smaller lighter refractors rather than reflectors. Check out a few vids and see...

[alanjgreen]

I must admit that I'd be tempted to get the mount you want (future proof) but start with something smaller scope wise. 

It will all be new to you and having to do it all with a big scope may push you over the edge to give up.

clear nights are at a premium in the uk and seems that starting small and learning all the software and winners and losers will all be cheaper and quicker with a smaller scope.

Getting it all out and putting it all away can be a real pain. I assume the RASA will also need more heating and dew control than something smaller too.

i know budget is no issue but dipping a toe in the water to test the temperature seems prudent to me.

if you learn fast then it's just a case to start upgrading the pieces to the end game.

the stars do really come around every year  

[Stu]

40 minutes ago, Orichae said:

I've seen similar-sized scopes at local events over the past year so do feel comfortable with the size in terms of what I have seen although have no experience in setting up and breaking down taking weight into consideration.
If need be I can always count on an extra pair of hands fortunately. Personally don't feel the need to see one in the flesh before I decide to commit but that's just me.

 

You seem quite clear about the way you want to go. Most people find it easier to start with a smaller scope and hone their techniques with those first, but if you are comfortable with operating and guiding a scope that big then I guess you should be ok.

[Scott]

sorry but I think looking at a 12" scope for a first off is madness. especially if you are lookjing at imaging nebula. If you want to spend money willy nilly, buy a mesu mount and chuck a smallish refractor on it and a descent ccd/cmos camera and filters. 

At the end of the day, it's your choice but for anyone to recommend a monster scope is not doing you any favours. 

Quote

 

 

[Scott]

10 minutes ago, Stu said:

You seem quite clear about the way you want to go. Most people find it easier to start with a smaller scope and hone their techniques with those first, but if you are comfortable with operating and guiding a scope that big then I guess you should be ok.

you're only saying that so you can grab it cheap 2nd hand when things don't work out

[Stu]

6 minutes ago, Scott said:

you're only saying that so you can grab it cheap 2nd hand when things don't work out

I reckon it would be pretty amazing as a video astronomy/EEA scope. Pity you couldn't stick Gavin's NV gear in it, guess you could if you had a really small head  

[Orichae]

4 hours ago, alanjgreen said:

f you learn fast then it's just a case to start upgrading the pieces to the end game.

the stars do really come around every year  

Love this comment Alan, thank you and does resonate.

I appreciate the numerous advice I've seen on starting small and i do not intent to throw away good money.
It's just that personally I really am looking for a challenge and simply enjoy learning, falling, standing up again over and over and do so until I am satisfied with the goals I set for myself.
As stated before I am not expecting stellar results out of the box but envision myself learning and improving over the course of 1-3 years.
I can start with a smaller scope, mount but know myself well enough that I would spent more time contemplating upgrade paths than I would be at getting from A to Z. This works best for me to get started.

Thanks for the insights, highly appreciated!
 

[ollypenrice]

Ok, I'll just say what I think and be damned! I took this with an 85mm refractor.

I think I improved it with a 106 refractor and a couple of years' more processing experience- and a bigger chip!

Do I think I would improve this by going to an enormous RASA? I do not. Not a chance. But check out the net, I might be totally wrong.

When you're a beginner you don't have much to go on beyond manufacturers' hype and loads of numbers. Let me give you an example of numbers.'You wouldn't want to image at 3.5 arcseconds per pixel, would you? Far too coarse. Terrible number, 3.5"PP. '  

https://www.astrobin.com/327970/?nc=iotd

Actually you do have more to go on than manufacturers' hype and numbers, thank goodness! You can spend a lot of time exploring the imaging boards looking for what people really use. One word of caution: when you see exotic kit giving great results bear in mind that its users will probably be very expert indeed. Personally I avoid 'difficult' kit becaue I like taking pictures, not fighting with kit.

Olly

 

 

[Stu]

Didn't realize quite how big the RASA is! That's a c11 next to it, not a C8!

[RayD]

1 hour ago, Orichae said:

Love this comment Alan, thank you and does resonate.

I appreciate the numerous advice I've seen on starting small and i do not intent to throw away good money.
It's just that personally I really am looking for a challenge and simply enjoy learning, falling, standing up again over and over and do so until I am satisfied with the goals I set for myself.
As stated before I am not expecting stellar results out of the box but envision myself learning and improving over the course of 1-3 years.
I can start with a smaller scope, mount but know myself well enough that I would spent more time contemplating upgrade paths than I would be at getting from A to Z. This works best for me to get started.

Thanks for the insights, highly appreciated!
 

Even as a fast learner, if this is your first venture in to AP, the learning curve is steep.  

If you start with a good mount and a smallish but still reasonable sized OTA, then the steep learning curve can be a very enjoyable one, and one that I myself have enjoyed over the last couple of years.  I think the danger is turning this in to a very steep and ultimately not enjoyable curve if you go in at a point that is ideally worked up to.

Olly's examples are superb demonstrations of just how good a smallish refractor can be, and Stu's example is brilliant to show how big the RASA is, because the 11" SCT isn't small by any means.

Whichever you choose, it's a very enjoyable but often frustrating path, so patience......lots and lots of patience.....is essential.

[Orichae]

1 hour ago, ollypenrice said:

Ok, I'll just say what I think and be damned! I took this with an 85mm refractor.

Wow just wow, that is incredible and I would be thrilled to be able to achieve a fraction of that kind of image.
At the end of the day, the RASA is a "fit for purpose scope" (AP only) correct? and considering @vlaiv comment earlier that aperture is important for AP surely there must be more to it then just marketing?

Perhaps I did went down the wrong rabbit hole and will ponder more on the advice given in contrary to my earlier comments before I commit.

 

 

40 minutes ago, RayD said:

Whichever you choose, it's a very enjoyable but often frustrating path, so patience......lots and lots of patience.....is essential.

This for me now also applies to choosing /selecting starting equipment for sure

[Waldemar]

In the end, it is your time, your money and your choice whatever decission you make. I appreciate the fast and steep learning tracks, too, but the road is rocky... Just a heads up:  In spite of what is being told about the RASA, it surely is an incredible instrument in all aspects... big, heavy, master lightbucket for ap, not so good for a DSRL, tricky to focus. Good choice for first scope? you will find that out... In all cases it is quite something!! 
if you need specific user information about it, I own one, just ask and if I can I will answer.

Wow, Olly.... Like you are showing, processing is the key, obviously  you master that as well... Chapeau!

 

[newbie alert]

There are couple of other things to consider with RASA - camera is mounted in front of objective, so you really want small / round camera body not to get into light path, and there is issue of cable management

that's what I was thinking!

for someone in in your position I'd recommend a 80mm refractor on a eq5 sized mount..plenty of years learning with just that.. you don't need a huge scope for nebulas..some will even be too big for the frame of the dslr