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#1 Vigilante

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Posted 20 March 2019 - 03:34 AM

Hi. I am about 3-4 weeks away from completing my AP set-up and wanted a little advice please. I should mention that I am new to AP and am jumping straight into the deep end. Please don't advise me to start with a smaller scope or a DSLR. I have made up my mind with the direction I am going in, realize it will be a steep learning curve but I look forward to the challenge.

 

I have been doing solely visual astronomy for the past 2 and a half years. I started with a Celestron 8se but upgraded the mount a year ago to a SW EQ6-R.. Which I plan to be my 'foundation' mount.. well at least for the time being. Over the last 2 years, I have been doing a tonne of research and joined my local astronomy club where I have been drawing on the knowledge of others. I will be doing most of my AP from bortle 6-7 skies (back yard) in Christchurch, NZ (We're all coming to terms with everything and feeling safer - thank you)

 

So, within the next month I will be buying the following equipment;

  • SW Esprit 120mm - bought locally 
  • ASI 1600 mm Pro, EFW and ZWO LRGB and 7nm NB filters (Ha, OIII and SII)
  • Either Guide scope or OAG
  • ASI 120 guide camera

My first question is given the weight of the Esprit (22lb) and the payload capacity of my mount (40lb I believe), am I better going for an OAG or a guide scope or is the weight negligible?

If I am to get a guide scope, what is a decent one to get?

Once all the gear is added, will my EQ6-R handle the weight? (I also plan on getting a USB Hub and maybe an ASI Air at a later date)

I also plan to do both my capture and processing from my PC indoors via cable link I dont have a Laptop. Am I best to get a auto focuser too and if so, do I need one for the GS if thats the way I'm going?

Are there any other equipment suggestions that will make my life easier with the above set-up?

 

Thanks for your help :)



#2 WadeH237

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Posted 20 March 2019 - 07:26 AM

Hi. I am about 3-4 weeks away from completing my AP set-up and wanted a little advice please. I should mention that I am new to AP and am jumping straight into the deep end. Please don't advise me to start with a smaller scope or a DSLR. I have made up my mind with the direction I am going in, realize it will be a steep learning curve but I look forward to the challenge.

You're actually not jumping into the deep end.  The focal length on the refractor is a bit longer than I'd recommend, but not unmanageable.  The mount you've selected will carry it fine.
 

My first question is given the weight of the Esprit (22lb) and the payload capacity of my mount (40lb I believe), am I better going for an OAG or a guide scope or is the weight negligible?
If I am to get a guide scope, what is a decent one to get?
Once all the gear is added, will my EQ6-R handle the weight? (I also plan on getting a USB Hub and maybe an ASI Air at a later date)
I also plan to do both my capture and processing from my PC indoors via cable link I dont have a Laptop. Am I best to get a auto focuser too and if so, do I need one for the GS if thats the way I'm going?
Are there any other equipment suggestions that will make my life easier with the above set-up?
 
Thanks for your help smile.gif

1) I think that a guide scope could work here.  The key would be to attach it to the focuser of the 120mm and not to the rings, or the body of the scope, or on a different (ie. side by side) dovetail.  An OAG would also work - and probably work better - but the setup would be more difficult.  Personally, I would go OAG, but that's because I have many configurations that I use to image and I have my camera and OAG more or less always attached together and move them as a single unit between different OTAs.  As for the weight, your EQ6-R won't care either way.

 

2) If you get a guide scope, one of the 50mm finder-type scopes should work fine.  The bonus is that you can usually mount something like this to the finder bracket on your main scope's focuser.  Pay particular attention to the focuser and how the camera attaches to it.  A non-rigid focuser and a camera connection that is not *rock solid* are two big places where flexure sneaks in.

 

3) Your mount will handle the weight.  As for the ASI Air, I am not at all sold on that platform.  I would much prefer a laptop (or NUC, or similar) at the scope.  That way you are not locked into a software stack and can run whatever you want.  To me, it seems like it's selling point is convenience, possibly at the cost of best results.

 

4) If you are going to work remotely, even just from inside the house, you want an auto focuser.  You won't need one for the guide scope.  The guide scope focus needs to be close, but it does not have to be perfect.  The guide software will be computing a centroid for the guide star, and this is tolerant of slight focus errors.

 

As for suggestions to make your life easier, don't try to jump right in to running remotely from inside the house.  You *will* need to get a computer out at the scope somehow, because you will be spending a lot of time in the beginning interacting with the gear and making adjustments.  The simplest routine example would be focusing.  Typically, I would focus a new system by having my software take repeated short exposures.  I'd then look at a 4:1 zoom, plus the computed FWHM, on the computer screen while making adjustments.  You could not do this from inside the house.  Beyond focus, you will likely need to make many other minor adjustments.  You'll also want to be at the scope in person, to see how it moves in response to your software's instructions.  You do not want to have the mount drive the scope into your tripod or pier, just because you aren't at the scope to see what's happening.

 

You should only move into the house after you are *completely* comfortable and proficient at running the system through every scenario while you are present at the scope.

 

Good luck and have fun!



#3 2ghouls

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Posted 20 March 2019 - 08:31 AM

Over the last 2 years, I have been doing a tonne of research and joined my local astronomy club where I have been drawing on the knowledge of others. :)


That’s good. On the OAG vs Guidescope question, I would go back to the expertise of your club. If you have a club member who has setup an OAG before and can help you, that would be invaluable. The weight difference is negligible between the two options, but you might want the OAG at that focal length. I’ve used up to 30 lbs on my EQ6 no problem. It’s only when I am approaching the mounts limits at 40+ with three counterweights at the end of the shaft that I have run into problems. My club has the new EQ6-r and it’s a great mount for sure!

Things you didn’t mention:
1. You will want a special cable to connect your EQ6-r to a computer and EQMOD. You will want lots of other software on that computer. Some of it may be paid software (SGP for example), although the open-source options are getting better now (KStars).
2. You will want processing software, and the time to learn to use it. Since you are jumping in to the deep end with equipment, you may be the kind of person to jump in to the deep end with processing in which case I suggest: PixInsight (PI). I would budget for that as well. Many of us use Photoshop (PS) in addition to PixInsight. While others are PixInsight purists. There are also many who use other software (APP, StarTools, etc), but PI and PS are the biggies, and there is a wealth of good online resources and videos to support learning them.
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#4 2ghouls

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Posted 20 March 2019 - 08:52 AM

I also plan to do both my capture and processing from my PC indoors via cable link I dont have a Laptop. Am I best to get a auto focuser too and if so, do I need one for the GS if thats the way I'm going?


Missed this part on first read-through. IMO you will absolutely need a motorized focuser on the scope that can be controlled remotely by your computer in this situation. I can’t imagine running in and out of the house multiple times every time I wanted to focus (which is multiple times a night). You have an uphill battle to get started imaging with all the complexity here, but with local support, you should be able to do it!!

What is the GS? Couldn’t find in your post what that is referring to...

Cheers, Nico

#5 dhaval

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Posted 20 March 2019 - 10:23 AM

My advice to people asking about guidescope or OAG, especially if you are starting out brand new is to get the OAG. It is a one and done thing. Once you have all the spacing and everything worked out and you achieve focus, you don't have to worry about it anymore. If you tear down your set up every night, you can still keep the camera and OAG all connected and stored as a single unit so that you are not mucking with it every night. OAG obviously has other benefits - no flexure to worry about and such. The less things you have to worry about in imaging, the better off you are.

 

With regards to Auto Focusing - IMO, after the mount, the single biggest thing that makes or break an image is focusing. You shouldn't skimp on that. So, if you can, get an auto focuser and have it set up with your image capture software. Also, make sure you get focusing offsets working. That will ensure focusing is a snap every time you change the filter.

 

You don't mention the software that you will be using to capture images. I would recommend  you take a close look at SGP. There are others out there as well. Everyone has their pros and cons. It will be best if you can test a couple of these image capture programs to see what you end up liking and spend the monies on the one that you like.

 

CS!  


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#6 bobzeq25

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Posted 20 March 2019 - 11:00 AM

Either the OAG or the guidescope can work.  It's hard to recommend one since you said you want to dive in deep and also said "easier".  The OAG is diving in, the guidescope is easier.  The OAG requires a more sensitive, more expensive guide camera, the guidescope can use an inexpensive ASI120MM mini.  You do not need autofocus for a guidescope, it's not critical.

 

If you do go for a guidescope which you get is nowhere near as important as mounting it rigidly.  Do not use a finder shoe.  Scroll down this page for examples of how to do it right.

 

https://www.cloudyni...ardrails/page-4

 

The mount is OK, but only OK, for that scope.

 

A Polemaster will make precise polar alignment easier. 

 

You need to think through your computer support for data acquisition carefully.  How are you going to connect everything up?  Mount, two cameras, filter wheel, maybe a focuser?

 

I have an Intel NUC at the scope that everything plugs into.  I connect it over my wifi network to my desktop, via TeamViewer.  Do most everything that way.

 

But, when you're polar aligning you need to be at the scope to work the controls.  I carry out a laptop, and also connect it to the NUC wirelessly, so I can use the PoleMaster.  If you don't get autofocus, you'll need to do that at the scope, also.  The laptop can be very basic, but most all of us have some kind of computer at the scope.

 

SGP is the established standard for data collection, some think the new Voyager is better.


Edited by bobzeq25, 20 March 2019 - 11:08 AM.


#7 TelescopeGreg

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Posted 20 March 2019 - 01:15 PM

+1 to what Bob said.

 

In addition, I would start assembling stuff a little at a time, getting the bugs worked out for each step as you go.  There's nothing harder than debugging multiple interacting issues all at once.  For example, get (or make) a Bahtinov mask for focusing now, then add the auto focuser after you have some images under your belt.  Going step by step will also guide you (no pun) on the particulars of the next step's purchase.

 

Having some compute power at the mount can help with cable logistics and overall reliability.  Some folks have reported no end of trouble trying to get reliable USB connectivity over distance for mount control, guiding, and imaging.  Depending on how far you are going, Ethernet, or even WiFi, can remote the at-scope's computer back to the house much better than trying to push the in-house computer's control out to the scope.  Little computers are really cheap these days.  I use a Raspberry Pi with PHD2 at the mount for guiding, but if you want to use something like SGP or Voyager for automation, I think a Windows box of some sort (e.g. the Nuc) may be required.  I'm not sure if the ASIAir has that level of functionality.

 

In general, when pushing the weight limits of a mount, balance becomes really important.  Very slightly "east heavy" for the RA motor, and a little nose or tail heavy for Dec.  Don't over-do, however.  You want to keep the gears meshed, not mashed.  Also, try to keep the center of mass in line with the bearings and counter weight.  When mounting the guide scope, for example, put it on top of the OTA, not on the side.  That keeps the balance constant as the telescope moves through the night.

 

Oh, also be sure you have an ample and stable source of power at the scope.

 

Good luck, and let us follow along on your progress with some images as you go!



#8 Vigilante

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Posted 20 March 2019 - 07:25 PM

Thank you everyone for the great advice so far.. lots to consider I know.

 

I will be using SGP for acquisition.. I believe it will help with Polar Alignment also which will be handy what with me being in the Southern Hemisphere and all!

I have budgeted for PI for the post processing.. maybe I will add PS at a later date. When I said I like to dive in the deep-end I still have my limits lol.

 

GS = Guide Scope. My set-up will be less than 10 meters from my PC. The Intel NUC is a good idea but seems a little pricey. I was going to just going to get a basic USB hub

 

Any advice on which motorised focuser to get for the Esprit 120mm?

 

Any advice on a more sensitive guide camera than the ASI120 MM?

 

Thanks again



#9 dhaval

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Posted 20 March 2019 - 08:39 PM

Thank you everyone for the great advice so far.. lots to consider I know.

 

I will be using SGP for acquisition.. I believe it will help with Polar Alignment also which will be handy what with me being in the Southern Hemisphere and all!

I have budgeted for PI for the post processing.. maybe I will add PS at a later date. When I said I like to dive in the deep-end I still have my limits lol.

 

GS = Guide Scope. My set-up will be less than 10 meters from my PC. The Intel NUC is a good idea but seems a little pricey. I was going to just going to get a basic USB hub

 

Any advice on which motorised focuser to get for the Esprit 120mm?

 

Any advice on a more sensitive guide camera than the ASI120 MM?

 

Thanks again

I didn't know SGP assisted in polar alignment - maybe that is a new feature? Having said that, PHD2 does have a polar alignment feature, that should work for the Southern Hemisphere as well - it is basically a drift alignment procedure aided by the camera.

 

For the Espirit 120mm, there is the nUSB motor from Rigel Systems. It is here in the US, not sure if you can get something down under. The Espirit focuser by itself should be good, so all you need to add is the motor to automate it.

 

Why are you discarding the 120MM without testing it? If you plan on using it with an OAG, the 120mm Espirit will catch plenty of photons to allow you select a few guide stars. I wouldn't be too worried about it, not without first trying it. 

 

CS!



#10 Vigilante

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Posted 20 March 2019 - 09:34 PM

Hi Wade

Thank you for your sound advice. I will be taking what you have said about being comfortable about set-up on board before running remotely.

 

Cheers



#11 Vigilante

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Posted 20 March 2019 - 09:49 PM

I didn't know SGP assisted in polar alignment - maybe that is a new feature? Having said that, PHD2 does have a polar alignment feature, that should work for the Southern Hemisphere as well - it is basically a drift alignment procedure aided by the camera.

 

For the Espirit 120mm, there is the nUSB motor from Rigel Systems. It is here in the US, not sure if you can get something down under. The Espirit focuser by itself should be good, so all you need to add is the motor to automate it.

 

Why are you discarding the 120MM without testing it? If you plan on using it with an OAG, the 120mm Espirit will catch plenty of photons to allow you select a few guide stars. I wouldn't be too worried about it, not without first trying it. 

 

CS!

Hi dhaval

Hmm, I'm sure someone at my astronomy club mentioned SGP now had a tool for Polar Alignment. I could be wrong.. none-the less, I know there are other software tools out there for this purpose.

 

I will definately check out that focuser - thank you.

 

Someone mentioned above that I might need something more sensitive than the 120MM if using a guide scope.. which tbh is the way I'm leaning.

 

Thanks heaps 



#12 zakry3323

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Posted 20 March 2019 - 11:43 PM

GS = Guide Scope. My set-up will be less than 10 meters from my PC. The Intel NUC is a good idea but seems a little pricey. I was going to just going to get a basic USB hub

 

Make sure you use an active USB cable at that length! 

Based on my experience with a 120mm, you'll probably be ok at that length and focal ratio guiding with an OAG even if you don't use a reducer, but that would really be topping out its capabilities and sometimes finding good guide stars might be a little challenging. There are options to make things a little easier. 


Edited by zakry3323, 20 March 2019 - 11:44 PM.

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#13 bobzeq25

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Posted 21 March 2019 - 12:19 AM

I used a 120MM on a 60mm F4 guidescope with absolutely no issues.  Never had to slew the guidescope to get a good guide star.

 

I believe it would be at best marginal with an OAG.


Edited by bobzeq25, 21 March 2019 - 12:20 AM.

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#14 dhaval

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Posted 21 March 2019 - 05:17 AM

Hi dhaval

Hmm, I'm sure someone at my astronomy club mentioned SGP now had a tool for Polar Alignment. I could be wrong.. none-the less, I know there are other software tools out there for this purpose.

 

I will definately check out that focuser - thank you.

 

Someone mentioned above that I might need something more sensitive than the 120MM if using a guide scope.. which tbh is the way I'm leaning.

 

Thanks heaps 

I used a 120MM and it worked just fine, as an OAG (behind a 130mm F7/910mm FL scope). Caveat - I have a set up in a remote observatory under Bortel 1 skies. Not sure what type of skies you have, but if you can swing it, try it. No harm trying it first and then figuring out if you need something else. 

 

CS!



#15 Stelios

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Posted 21 March 2019 - 10:47 AM

The recommendation for an OAG is an ASI290MM-mini. The 120MM-mini is not as sensitive, and there are patches of the sky with guide stars in short supply for OAG. (And yes, Bortle 1 skies would make all the difference. The rest of us can only be envious).

 

For a *guidescope*, the 120MM-mini is more than enough, even in central Los Angeles.


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