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Help me “beat” an Omni XLT 150mm + CG-4

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#1 cgguido

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Posted 28 June 2022 - 06:16 AM

Hello everyone,

I’m looking to buy my first telescope. Budget is under $1000, ideally under $800. My backyard is in the suburbs of Chicago, known for its carbon-black skies..

Was initially leaning towards an 8” f6 dobsonian but I think a shorter and smaller tube and a “foldable” mount/tripod would help in getting it into the trunk of a CR-V. Back seats are taken up by two kiddos. Also considered a flextube but given that the base does not fold I’m not sure how much space saving that is… finally, I’d like a fast-ish aperture and would probably dabble with astrophotography. Something transportable with kids and tents, that gives good viewing experience now and offers some sort of upgrade path in the future…

The Omni XLT 150 is 750mm at f/5. Comes with a single speed 2” crayford focuser and a few other bits… but not as many as, say, and AD8 dobsonian.

The CG-4 can carry 20lb and can be fitted later with a polar scope and two motors to track for a taste of astrophotography.

Besides ocular lenses and better finders etc, the obviously upgrade would be a good mount at some point…

Any suggestions on how to start on a better footing?

Many thanks!
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#2 LunarObserver

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Posted 28 June 2022 - 07:50 AM

I have a cg4 mount with motor drives. For smaller telescopes i love it!  No it is not made for long exposure imaging but uis very portable and pretty steady. 
Best wishes 

David


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#3 Chad7531

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Posted 28 June 2022 - 08:02 AM

I love my 6” F5, I started with a couple of smaller reflectors and the 6” was the first one I was happy with. It’s still light and portable. It cools down fast and gives great views of the moon and planets. When I started taking it to a dark site for DSOs though I wasn’t all that impressed. I could see galaxies but they were faint smudges. So I got a 10” dob for DSOs and use my 6” at home in the light pollution for quick looks at the moon and planets. My 10” lives at my dark site for it’s much better views of galaxies and other DSOs. If I were just starting out now, after having four different aperture reflectors and could only have one for all of my viewing needs, I’d get an 8” dob.

Edited by Chad7531, 28 June 2022 - 08:03 AM.

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#4 Astroman007

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Posted 28 June 2022 - 08:03 AM

If you are patient, you can find a very decent 4" apo that would "beat" the Celestron Omni in our very own CN Classifieds. There is no need to buy new, and you can get more ""bang for your buck" by buying second hand but well maintained...if not mint.



#5 vtornado

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Posted 28 June 2022 - 08:06 AM

I assume you are referring to a 150 reflector (there are also variants of a 150mm frac). The CG4 can carry a 6 inch f/5 reflector.  No bigger though.  I have been using it for EAA with a 130mm f/5 reflector.

 

6 inch f/5 is a very capable scope.  Just the right size,  big enough to pull in some

bright deep sky objects and not too big where it becomes a chore to take out and setup.

 

A 5 inch SCT is very portable, it is more money.  A .63 reduce brings it down to around 720mm.  Less collimation issues, but more dew issues.    I'm not saying it is better than the 150 newt, just different.

 

 

if you are patient, you can find a very decent 4" apo that would "beat" celestron omni ...   I might call it a tie, and a lot more money even used.  Most ED 100 scopes start at f/7 and 700mm f/l.  Refractors have less cooling and colimation issues if that is important to you.


Edited by vtornado, 28 June 2022 - 08:16 AM.

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#6 zxx

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Posted 28 June 2022 - 08:20 AM


The CG-4 can carry 20lb and can be fitted later with a polar scope and two motors to track for a taste of astrophotography.

 

You also can add a guide port to the drive kit for guiding ,I did this simple mod and it works vary well for AP with my 

ed80.



#7 jupiter122

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Posted 28 June 2022 - 09:26 AM

Seems to me that you may have a hard time getting that scope mount and tripod in the trunk of a CR-V, especially if you have any of them in a carrying case,which you may very well want.

good luck and have fun.

Tim

#8 csrlice12

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Posted 28 June 2022 - 11:56 AM

The CG4 takes up more space than you think.....Had the motors on mine and took them off.  You lose your RA Slomo control and the circuit board connections are exposed and flimsy.  Just found it easier to use with manual controls.  That being said, the CG4 is an excellent beginners EQ mount.  Also consider a 6" f8 dob....same aperture, easier to set up and tear down, easier on eyepieces and normally holds collimation better.


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#9 SeattleScott

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Posted 28 June 2022 - 05:07 PM

I have a CRV. Assuming padded foam case for scope and likely no case for mount, shouldn’t be any problem fitting them in back of CRV. I think I even did measurements to confirm my 10” reflector tube will fit in back of CRV actually, although that’s definitely pushing it.

The CG4 with 6” reflector is a solid approach. Could even configure mount as Alt Az to eliminate tube rotation, although you would lose tracking. A 4” Apo is another option, lower maintenance, easier for kids to look through.

You mentioned stargazing with kids. The problem is your kids might be a lot shorter than you. So a reflector, which involves viewing through the top of the tube, might be fine for you but hard for them. A refractor which views through the bottom of the tube could be easier for them but now you are on your knees. Something to consider. Do you want to bring a step stool for them, or a chair for you?

Scott

#10 Chad7531

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Posted 28 June 2022 - 05:21 PM

I have a CRV. Assuming padded foam case for scope and likely no case for mount, shouldn’t be any problem fitting them in back of CRV. I think I even did measurements to confirm my 10” reflector tube will fit in back of CRV actually, although that’s definitely pushing it.

The CG4 with 6” reflector is a solid approach. Could even configure mount as Alt Az to eliminate tube rotation, although you would lose tracking. A 4” Apo is another option, lower maintenance, easier for kids to look through.

You mentioned stargazing with kids. The problem is your kids might be a lot shorter than you. So a reflector, which involves viewing through the top of the tube, might be fine for you but hard for them. A refractor which views through the bottom of the tube could be easier for them but now you are on your knees. Something to consider. Do you want to bring a step stool for them, or a chair for you?

Scott

I’m 5’6” and hunch way over on a 10” f5 with a 3” platform at zenith. My 6” f5 on a mount I’m basically sitting down at zenith but I’m not because I observe standing. They aren’t that tall.

Edited by Chad7531, 28 June 2022 - 05:21 PM.


#11 cgguido

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Posted 28 June 2022 - 07:07 PM

Thank you all for your inputs. Here are some thoughts:

 

My instinct is to get an OTA geared more towards imaging (6" f/4 by Apertura or SW perhaps?) and (for now and for observation only) bias the mount towards a solid AltAz (no idea, used would be just dandy here especially, suggestions?).

 

My thinking is that a fast 6" newt should:

  • be more compact than a 6" f/8 dob tube (increasing its changes to come outside and on camping trips)
  • use a mount and tripod that are more collapsible/take-apart-able than a dob base
  • include a solid focuser (for imaging eventually)
  • be optically performant, in general.

I gather that the three principal drawbacks would be:

  • that is requires good collimation to shine (I am not too concerned with this one as I am an experimental physicist by training, tinkering is fine by me)
  • that it has more coma at the edges of the field of view (this can be corrected with, say, an Apertura A-COMA for their 6" f/4 right?)
    • btw, is coma alleviated when using higher mag eyepieces, since they focus on center of field of view?
  • that to do very long exposures it requires a mount of the calibre of an EQ6-R pro (In photography you date your cameras and marry your lenses, I am planning on marrying a mount, when I have the money for the wedding, so to speak... I'd be ok doing visual on an alt az for now)

 

Am I making any sense?

 


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#12 sevenofnine

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Posted 28 June 2022 - 10:39 PM

If AP is really in your sights then a good guide book is in order IMO. A very experienced member on this forum recommends reading this one... Before you buy any equipment! Many have said that you should treat visual and AP as two different hobbies that require very different equipment. I've started this book and that's my conclusion too. Good Luck! waytogo.gif

 

Charles Bracken's "The Deep-Sky Imaging Primer 3rd ed." 

https://www.amazon.c...mcx_mr_hp_atf_m.


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#13 SeattleScott

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Posted 28 June 2022 - 11:00 PM

Of course remember F4 is tough on eyepieces. I sometimes use a R200 on my AZ4 for sort of grab and go visual. 8” aperture and 35lb for the whole setup. I can pick it up and move it to tree dodge. That being said, I have the coma corrector and the premium eyepieces to handle that light cone.

Scott
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#14 vtornado

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Posted 29 June 2022 - 12:59 PM

btw, is coma alleviated when using higher mag eyepieces, since they focus on center of field of view?

 

Yes all reflectors have what is called a coma free zone.  That is a zone in the very center

of the field.  As the f ratio decreases the zone gets smaller.  This can be mitigated with a coma corrector.

 

I image with a 130 f/5 reflector with a 1/3 inch chip.  I do not see coma.  I'm sure if I 

got a large chip camera it would be more apparent. I do EAA on a CG4 mount.  To date, (I still have lots to learn) I get around 15 seconds without bloat.

 

A dob base can be used to store clothes or something else soft like that.  All other things equal a 6 inch f/4 is half as long as a 6 inch f/8.  Tripods do fold much flatter than a dob base.  They are longer.   You will not be able to motorize the f/8 dob without a major headache.  

 

Of course remember F4 is tough on eyepieces. -- SeattleScott.

Is this true of all eyepieces or just low power / wide fields?



#15 SeattleScott

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Posted 29 June 2022 - 01:48 PM

All eyepieces. F4 means edge distortion in affordable wide AFOV eyepieces. Now one might object to this more at low power because they are trying to use the whole view to find targets, as opposed to high power viewing looking at small targets in the center of the field. So it might be the edge distortion is most notable at low power, but it’s always there. This can be mitigated by using narrower AFOV eyepieces around 50-60 AFOV. Where you really see problems are with the affordable 70-80 AFOV eyepieces.

Scott

#16 BlueTrane2028

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Posted 29 June 2022 - 01:56 PM

I've been using the CG4 with a Celestron 6" SCT to great effect.

Haven't dragged out a Dob in a long time to be honest...

51940443149_52a83bbc67_b.jpg

The CG4 is also great with a 120mm f/5 achromat.  Very nice wide field views in that.

51843692538_ab76c944a0_b.jpg

All of that can be had within your budget if you search carefully.




I had a 6" f/5 reflector in the form of an Orion Starblast 6.  Actually, I had two different Starblast 6s.

Didn't like them.  Views were mushy.  I hope the Celestron optical tube is nicer than the Starblast 6 if you go that route.


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#17 BlueTrane2028

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Posted 29 June 2022 - 03:38 PM

Also, no need to keep yourself only with the CG4.  Sometimes bigger mounts come along cheaply.

This LXD-500 (CG5 class manual EQ mount produced by Meade) came up on Facebook for $100 last week.  It needed some work but it's great now.  It's heavier than the CG4 but it's oddly more convenient, as the tripod folds up with the head still attached.  Unfold the tripod, point it North, install counterweight and OTA... observe.  Almost as fast as any Dob now.

52182657556_d54ba2797c_b.jpg


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#18 radiofm74

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Posted 04 July 2022 - 02:33 AM

I've been in your shoes and know first hand some of the rigs being suggested:

1. I have the OMNI 150 and it is a wonderful first kit. No, it's not hike-a-ble but carrying it around with a car should not be too difficult and set-up/tear-down time is very fast with a bit of practice. For urban observation, budget for a bigger finder (I use a combination of 8x50 RACI and a red dot). Do not expect it to do long-exposure astrophotography. It's a visual scope. But with a DSLR attached (it comes with all the right threads…) you sure can do lunar (see attachment). My suggestion would be: check if it fits your trunk, and if so buy one (used) without second thoughts. You may want to sell it down the road, but that's a few years and many observations from now.

2. If you want more portable, your budget might accommodate a nice portable mount (e.g. a Vixen Advanced Polaris) and a C6 OTA if you buy used judiciously. Budget for a Celestron 0.63 reducer or finding objects will be difficult indeed as a beginner. This is also a good visual rig – I've been everywhere with it. It could be developed into an advanced DSO imaging rig. But it would be a difficult, difficult beginner DSO rig due to the long focal length. 

3. If you want to start out in DSO imaging, the strategy will be different: a sturdy GoTo mount, a 3" or so refractor… But realise that this very capable photographic set will be far less capable visually. There is no one rig fitting well both needs for a beginner wanting to spend 1000$.

 

I'd go with option 1, then after a year if you still have the itch start building your imaging rig. 

 

VP5TKGOh.jpg


Edited by radiofm74, 04 July 2022 - 02:48 AM.

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#19 avongil

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Posted 07 July 2022 - 01:35 PM

Not sure if the celestron product is similar to the orion short tube 6" newts, but I absolutely hated my Starblast 6. Terribly soft image. 

Id say you are better off with a C6 and a focal reducer. 

 

 


Edited by avongil, 07 July 2022 - 01:40 PM.


#20 avongil

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Posted 07 July 2022 - 01:37 PM

Considering the pic of the moon I just saw, the 150 XLT is not the same beast as the StarBlast. Or maybe my example was junk, but to this day I have not heard of anyone with a sharp starblast 6.

 

Id seriously consider what Mr BlueTrain posted.  A 120 frac has no central obstruction so the light gathering should be similar. What you gain in color you loose in diffraction spikes.  No maintenance and more portability.

 

The C6 is kind of the middle ground if you ask me.  Super sharp images, but not as wide.  Very portable with little collimation. 

 


Edited by avongil, 07 July 2022 - 01:45 PM.

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#21 Echolight

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Posted 07 July 2022 - 03:09 PM

Considering the pic of the moon I just saw, the 150 XLT is not the same beast as the StarBlast. Or maybe my example was junk, but to this day I have not heard of anyone with a sharp starblast 6.

 

Id seriously consider what Mr BlueTrain posted.  A 120 frac has no central obstruction so the light gathering should be similar. What you gain in color you loose in diffraction spikes.  No maintenance and more portability.

 

The C6 is kind of the middle ground if you ask me.  Super sharp images, but not as wide.  Very portable with little collimation. 

 

C6 is kinda more expensive unless you score a used one.

 

I always liked the idea of an ST120. But it was more than I wanted to spend, and too big.

 

So I got the little brother, a StarTravel 102.
OTA is $280 shipped to the US, roughly, from Firstlight Optics in the UK.

$400 with the HD tripod from US vendors. But I don't recommend the tripod.

 

Mines riding on a used Bogen 3040 with a ball head. A 3046 with 3-way head can be found on CL for around a hundred dollars, maybe less. A 3036 or 3051 are also good options for this size scope.

 

A sweet little setup with BIG views that's easy to get out, easy to look though, just plain easy to use.

E5B7C670-D9B8-408F-9108-16D7B5717B87.jpeg

 

 

CA shme-ay. This thing gives sharp views at well over 150x, zoom and a barlow, $200 on a budget. A little purple on the limb of the Moon never killed anyone.
And an easy 4.6 degrees widest field richest field views with a decent 2 inch eyepiece, AT28UWA, $200. You'll need a 2 inch diagonal to use it, $150.

 

So not counting the eyepieces, which you'd likely want to add to any scope, you're at about $550 for scope, mount, and 2 inch diagonal. Add a couple hundred for to upgrade over the used Bogen to a real alt-az mount. But I'd rather put that towards eyepieces.

 

Another look

7F243343-747C-48AB-A507-25BA409B9739.jpeg

 


Edited by Echolight, 07 July 2022 - 03:22 PM.

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#22 SeattleScott

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Posted 07 July 2022 - 03:23 PM

A buddy had a 6” F5 Celestron reflector. It gave sharp views when collimated, similar to a good 6” Mak, maybe just slightly lagging. Couldn’t really compete with a 6” refractor naturally.

Scott
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#23 Echolight

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Posted 07 July 2022 - 03:52 PM

I liked my 6 inch f5 newt pretty well. It was just a lot bigger and trickier to mount than I thought it would be.

 

The CG-4 mount will place the eyepiece high if you like to view while seated.


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#24 radiofm74

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Posted 07 July 2022 - 03:56 PM

As to how sharp an OMNI 150 XLT can be if properly collimated: mine goes down to Dawes' limit without a problem. I've split Zeta Cancri cleanly, as also STT186 (0.8" separation) and in terms of pure image quality it's as good if not perhaps slightly better than my C6. The point, though, is that the C6 is a lot smaller and easier to mount, so I've literally taken it everywhere whereas dear old Newt has resided under Bortle 9 for all its life. 

 

But again, as a first scope and fine all-rounder doing well planets, doubles, lunar and DSOs, plus having a pleasantly wide field, a 6" Synta Newtonian is a really good option. 

 

Echolight's ST102 is also an option worth considering long and hard. It's very affordable, very easy to use, and I've never read of anyone being unhappy with it – not once. 

 

Ease of use is pretty crucial when you start out


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#25 radiofm74

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Posted 07 July 2022 - 03:57 PM

I liked my 6 inch f5 newt pretty well. It was just a lot bigger and trickier to mount than I thought it would be.

 

The CG-4 mount will place the eyepiece high if you like to view while seated.

That's a valid point too. If you get the Newt on a CG-4 mount, which is a very good combination, you should probably also get an astronomy chair to be really comfortable. Not must-have, but very nice to have.




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