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Hubble Optics UL20G~Good upgrade from ES 16" Truss Tube?

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#1 ronbriggs44

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Posted 11 December 2023 - 02:32 PM

Hi Everyone,

 

I currently have an Explore Scientific 16" Truss with the Nexus encoders I use with Sky Safari. I have had it for a little over a year and have completed the Messier List and am working through the Herschel 400. I am looking to upgrade (more aperture, go-to to hold the target as I am showing others, and hopefully better optics). I want a scope with about the same height at Zenith so I do not have get a ladder out (I am 6-3). All of these things on my wish list are pointing me towards the HO UL20 in the 3.7. Does anyone have one of these and would you recommend it (or not)?

 

And if anyone lives near Ventura CA with one and would be willing to meet up, that would be great! I realize that about 50% more light will not make a massive difference, but this is the biggest scope I want to handle and observe through. I will be on my third and, hopefully, last one for awhile until I move to a dark sky site when I retire!

 

And if anyone has questions about the ES 16' and/or the Nexus, or stargazing experiences near Ventura/Ojai/Santa Barbara feel free to ask.

 

Stable Skies

 

Ron

 

IMG_6516 reduced.jpg


Edited by ronbriggs44, 11 December 2023 - 02:47 PM.

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#2 MeridianStarGazer

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Posted 11 December 2023 - 03:01 PM

Sounds like 8" vs 10". Some say you must go up a magnitude to be worth the cost of switching, while others say every inch counts and you should get the biggest scope you don't mind setting up. Only you know if any money loses are an issue for you.

Others will answer about how good the quality of the HO 20 is. Are you unhappy with the ES16 quality?

If I could easily move a 10" and had plenty of money, I would get one to replace an 8". But for me, the weight difference might affect how often I observe. And I'm not made of money. So I will stick with an 8". I have nothing against gaining a few inches.
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#3 MeridianStarGazer

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Posted 11 December 2023 - 03:06 PM

Also, my best view ever of M51 was in a 20". It blew away what I saw in a 25" and an 18". Even the view in a 10" had more detail than those. It really depends on the sky, where in the sky it is, the magnification, your coatings not being too dusty, and your coatings not being too old. The extra 5" are not all that matters. But the smallest I saw obvious dust lanes was in a 10".

It was a 10" SCT. I'm guessing their coatings last longer and have less dust on them.

Edited by MeridianStarGazer, 11 December 2023 - 03:07 PM.


#4 Waynosworld

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Posted 11 December 2023 - 03:17 PM

I have a UL20 F/3.7, but it is an older version that had a cable drive for altitude, and a Lazy Susan bearing for AZ that was run by a small rubber wheel, it was bought by the original owner for a small Observatory, the primary mirror is great.

 

The fact is I have modified it so much(and plan more mods) that it can hardly be called a Hubble Optics telescope anymore, I removed the electronics as I am a visual observer only, I have no use for the electronics, and it was annoying to use with the hand controller, as I mentioned it was an earlier version, the photos of the newer versions are completely different.

 

Keep in mind that I modified mine for ease of use, I put it on wheels to make it easy to move around, I put a traditional UTA on it for dew control, I had to change/make a new mirror cell as the original was flexing, when I did all that I also lowered the mirror cell to get the eyepiece down lower(I am just under 6' now), but now I am likely going to make a new mirror cell base to lower the eyepiece another 3+ inches as I am on my tiptoes now at zenith, when I bought it used I had to use a cement block(6" high) to observe at zenith, here it is on the wheels with the first UTA I made for it.

 

DSC00449.JPG

 

Here it is with the better much lighter UTA made of 2 aluminum bike wheels and some thin ABS sheeting.

 

DSC00600.JPG

 

I would also echo that I can hardly tell the difference between my 16" F/4.42(Hubble Optics sandwich mirror) dob I made from bought parts and parts I made from scratch and the 20" above using the same eyepiece, but I made the 16" as a travel dob, it weighs 65 pounds(with wheels).

 

DSC00948.JPG


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#5 MeridianStarGazer

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Posted 11 December 2023 - 04:03 PM

...

I would also echo that I can hardly tell the difference between my 16" F/4.42(Hubble Optics sandwich mirror) dob I made from bought parts and parts I made from scratch and the 20" above using the same eyepiece, ...


You also said the same about your 12 vs 16.

I compared 6 vs 8 on M51 once, same magnification, not so dark sky. How big the difference is definitely depends on the object, the sky, and the magnification.

One advantage of 20" is you are more likely to see color. And someone else is more likely to get a good deal on a 16".
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#6 ronbriggs44

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Posted 11 December 2023 - 04:08 PM

I have a UL20 F/3.7, but it is an older version that had a cable drive for altitude, and a Lazy Susan bearing for AZ that was run by a small rubber wheel, it was bought by the original owner for a small Observatory, the primary mirror is great.

 

The fact is I have modified it so much(and plan more mods) that it can hardly be called a Hubble Optics telescope anymore, I removed the electronics as I am a visual observer only, I have no use for the electronics, and it was annoying to use with the hand controller, as I mentioned it was an earlier version, the photos of the newer versions are completely different.

 

Keep in mind that I modified mine for ease of use, I put it on wheels to make it easy to move around, I put a traditional UTA on it for dew control, I had to change/make a new mirror cell as the original was flexing, when I did all that I also lowered the mirror cell to get the eyepiece down lower(I am just under 6' now), but now I am likely going to make a new mirror cell base to lower the eyepiece another 3+ inches as I am on my tiptoes now at zenith, when I bought it used I had to use a cement block(6" high) to observe at zenith, here it is on the wheels with the first UTA I made for it.

 

attachicon.gif DSC00449.JPG

 

Here it is with the better much lighter UTA made of 2 aluminum bike wheels and some thin ABS sheeting.

 

attachicon.gif DSC00600.JPG

 

I would also echo that I can hardly tell the difference between my 16" F/4.42(Hubble Optics sandwich mirror) dob I made from bought parts and parts I made from scratch and the 20" above using the same eyepiece, but I made the 16" as a travel dob, it weighs 65 pounds(with wheels).

 

attachicon.gif DSC00948.JPG

 

Thank you for the thorough reply! Yes, I do not love the UTA on the UL20. Interesting design both for dew and stray light. Not sure why they don't use a solid (or at least cage like the ES) so you can easily wrap it. Probably trying to save weight, but I like the secondary tucked down and not exposed. But they probably know what they are doing.

 

Thank you for the input on the difference in your experience of 16" vs 20".  I guess I should keep the 16" for more portability and flat footed viewing and think about a second scope like the HO UL 24 or the Obsession 22UL.  And get a good step stool. :-)

 

To answer the other reply, I am satisfied with the ES 16, but I am also thinking the optics in the Hubble might be better and 50% more light isn't nothing. I realize this is a conundrum for many of us! 


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#7 grzesznypl

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Posted 11 December 2023 - 04:11 PM

Sounds like 8" vs 10". Some say you must go up a magnitude to be worth the cost of switching, while others say every inch counts and you should get the biggest scope you don't mind setting up. Only you know if any money loses are an issue for you.

I respectfully disagree. Difference between 16" and 20" is not entirely the same as difference between 8" and 10" even though numbers are similar. 0.5 magnitude and 56% more light may not be a wow factor but it is a noticeable improvement when observing very faint objects. The difference will be even more striking particularly while observing from dark site. I've done few of those comparisons and my conclusions is that upgrading from 16 to 20" makes sense only when you want to keep larger telescope. It seems to me that's what OP wants to do, buy 20", get rid of 16" and enjoy 4 extra inches of aperture and possibly better optical quality.
 

 

I would also echo that I can hardly tell the difference between my 16" F/4.42(Hubble Optics sandwich mirror) dob I made from bought parts and parts I made from scratch and the 20" above using the same eyepiece ....

Again the difference will be much more evident while observing from true dark site. On the side note, the only meaningful way of comparing two different telescopes with two different apertures and focal ratios would be using different eyepieces to match magnification and not using same eyepiece. Mel Bartels had demonstrated it once using 6" f/2.8 and 13" f/3.0 telescopes (picture below, link)

Sombrero%20Galaxy%20through%206%20and%20


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#8 Inkie

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Posted 11 December 2023 - 04:32 PM

Also, my best view ever of M51 was in a 20". It blew away what I saw in a 25" and an 18". Even the view in a 10" had more detail than those. It really depends on the sky, where in the sky it is, the magnification, your coatings not being too dusty, and your coatings not being too old. The extra 5" are not all that matters...

I can't help but wonder at the various differences between the scopes you mention, not least of which might have been their degree of collimation and cool-down.  I have a hard time accepting that even a B grade 25" mirror (ARE there any B grade 25" mirrors?!) would place second to a mere 20"er. There was something else afoot.  Were these compared on the same objects, same time?  Even if so, there's a lot else that could have separated their renditions.


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#9 Waynosworld

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Posted 11 December 2023 - 04:42 PM

You also said the same about your 12 vs 16.

I compared 6 vs 8 on M51 once, same magnification, not so dark sky. How big the difference is definitely depends on the object, the sky, and the magnification.

One advantage of 20" is you are more likely to see color. And someone else is more likely to get a good deal on a 16".

Yes them upgrades are baby steps, I also have mentioned that going from a 10" to a 12" is a substantial upgrade, I can definitely observe a big difference between them compared to going from 12" to 16" or a 16" to a 20".

 

All my comparisons are from my bortle 7+ backyard, when I go to a dark site I take the 16" F/4.42 and my NP101 Refractor, I can observe/see way more at a dark site.

 

I have had my best view of Saturn at a dark site, I have had better views of both Mars and Jupiter from my Bortle 7+ backyard, I think the conditions are very important also.

 

If I had known the difference was so small between the 16" and 20" I would not have bought the 20", I was looking for a 24" but all that showed up was the 20", since then I decided I would not have likely liked the ease of use of the 24", I need something that can easily be moved around(on wheels), if I had to pick either the 16" or 20" right now, I would keep the 16" travel dob, with them Teeter side bearings it is an absolute pleasure to use and I can observe at zenith flat footed.


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#10 ronbriggs44

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Posted 11 December 2023 - 04:49 PM

I respectfully disagree. Difference between 16" and 20" is not entirely the same as difference between 8" and 10" even though numbers are similar. 0.5 magnitude and 56% more light may not be a wow factor but it is a noticeable improvement when observing very faint objects. The difference will be even more striking particularly while observing from dark site. I've done few of those comparisons and my conclusions is that upgrading from 16 to 20" makes sense only when you want to keep larger telescope. It seems to me that's what OP wants to do, buy 20", get rid of 16" and enjoy 4 extra inches of aperture and possibly better optical quality.
 

 

Again the difference will be much more evident while observing from true dark site. On the side note, the only meaningful way of comparing two different telescopes with two different apertures and focal ratios would be using different eyepieces to match magnification and not using same eyepiece. Mel Bartels had demonstrated it once using 6" f/2.8 and 13" f/3.0 telescopes (picture below, link)

Sombrero%20Galaxy%20through%206%20and%20

And philosophically speaking...there must be a significant (being a relative word) difference (increasing aperture by 4 inches) or else anyone thinking of getting a 20" would save money and effort by just getting a 16", but why stop there? 16" probably doesn't improve much over a 12"... and so on. :-)  

 

Ideally I would be able to put them head to head like in the post above with qualitative data. If I do not find someone locally with a HO 20, I will need to start looking for star parties or dealer demo nights (if there is such a thing) so I can "see" for myself. I will post elsewhere asking about where to find such gatherings. Unless someone here has any good ideas.

 

And if I do find someone and I can do a comparison, I will post the details. My guess is (if it is a dark sky) the objects will be a little brighter and a little more defined and there may be objects that the 20" can just barely make out while the 16" doesn't see them. I know...I just answered my original question. lol.gif lol.gif  But I would still like to see it before I pull the trigger.



#11 Waynosworld

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Posted 11 December 2023 - 04:50 PM

Thank you for the thorough reply! Yes, I do not love the UTA on the UL20. Interesting design both for dew and stray light. Not sure why they don't use a solid (or at least cage like the ES) so you can easily wrap it. Probably trying to save weight, but I like the secondary tucked down and not exposed. But they probably know what they are doing.

 

Thank you for the input on the difference in your experience of 16" vs 20".  I guess I should keep the 16" for more portability and flat footed viewing and think about a second scope like the HO UL 24 or the Obsession 22UL.  And get a good step stool. :-)

 

To answer the other reply, I am satisfied with the ES 16, but I am also thinking the optics in the Hubble might be better and 50% more light isn't nothing. I realize this is a conundrum for many of us! 

I bought a 14.5" F/4.5 Starsplitter for my first large dob, I had so many issues because of that thick primary mirror it had, some nights it never cooled to ambient temps, it drove me crazy, I bought the Hubble Optics 16" F/4.42 sandwich mirror and built my dob around it, that was the best decision I have ever made in this hobby so far.


Edited by Waynosworld, 11 December 2023 - 04:51 PM.

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#12 Skyscratcher88

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Posted 12 December 2023 - 10:59 AM

In my experience it is sky conditions and darkness that make the biggest difference.

I took my 6” skywatcher dob to Cherry Springs PA (B2) this past early Summer and observed M97 Owl, M57, M27, CatsEye Nebula, M104 Sombrero Galaxy and a plethora of things in Sagittarius. The transparency was exceptional. The 6” in these conditions significantly out preformed my 10” Dob from home B5 skies.

The most remarkable night of astronomy was observing from high altitude in Utah B1. I was in my mid-20s and had a Astroscan 4.25” (redball scope) running through the spring galaxy clusters was unbelievable. The contrast on M64 (Blackeye galaxy) was picture like. I have not been able to duplicate that experience since. Even with 10” and in B2 conditions.

A good 8” and the ability to get to dark skies regularly beat a 20” from lesser skies IMO (I have looked through up to 25” dobs) Now of course a 20+ from those same skies wound crazy good but at less FOV and much more hassle.

I am currently taking ownership of a 15” dob while I am still fit and healthy but I know when the newness wears out it will be much harder to get motivated to take it out regularly. I’ll still keep my 6” and 8” SCT GnGoes.

Here is what 6-8” can do from dark skies!

https://www.deepskyw...o-sketches.html
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#13 MeridianStarGazer

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Posted 12 December 2023 - 01:39 PM

My best view of the double cluster was in a 5", and not because of the field of view. The sky transparency blew away the views I had in scopes up to 20" from other dark clear locations. You don't know what you are missing till you see a great clearing. Your best chance at seeing one is to use a scope that gets you out often. If big aperture motivates you to observe, great. But great clearings often only last a few minutes. So you better be looking when they come. I would like an ultra wide angle IR sensor that tells me where the clear holes are, so I can point my scope there. Most light pollution does not reflect back when there is a great clearing, so even observing from home is possible if you are dark adapted. I'd want a sensor atop an observatory, and track how often they are.
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#14 ronbriggs44

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Posted 12 December 2023 - 03:55 PM

In my experience it is sky conditions and darkness that make the biggest difference.

I took my 6” skywatcher dob to Cherry Springs PA (B2) this past early Summer and observed M97 Owl, M57, M27, CatsEye Nebula, M104 Sombrero Galaxy and a plethora of things in Sagittarius. The transparency was exceptional. The 6” in these conditions significantly out preformed my 10” Dob from home B5 skies.

The most remarkable night of astronomy was observing from high altitude in Utah B1. I was in my mid-20s and had a Astroscan 4.25” (redball scope) running through the spring galaxy clusters was unbelievable. The contrast on M64 (Blackeye galaxy) was picture like. I have not been able to duplicate that experience since. Even with 10” and in B2 conditions.

A good 8” and the ability to get to dark skies regularly beat a 20” from lesser skies IMO (I have looked through up to 25” dobs) Now of course a 20+ from those same skies wound crazy good but at less FOV and much more hassle.

I am currently taking ownership of a 15” dob while I am still fit and healthy but I know when the newness wears out it will be much harder to get motivated to take it out regularly. I’ll still keep my 6” and 8” SCT GnGoes.

Here is what 6-8” can do from dark skies!

https://www.deepskyw...o-sketches.html

Absolutely. When you have ink black skies in the eyepiece, all scopes can be amazing. For me, if I go from 16" to 20", it will not make a difference in usage or set up. All the places I travel to (which I have to since my backyard skies are not dark at all) with my 16" will all be getable with a 20".  Makes no difference. I may need to have the mirror box on wheels and roll it in and out. I can manhandle the 16", but I prob should be rolling that too so I don't have a weird back injury while I am in the mountains behind Ojai on my own. smile.gif smile.gif  Other than that attaching everything is about the same.  I would like to get a solid OTA for quick missions. I do miss the ease of my 8". Plop down the base, set the tube and start exploring. Maybe I should keep the 16" and instead invest in a nice 12.5 Parallax. But then I might never set up the 16...laugh.gif laugh.gif Because like people have said above, there isn't much difference between a 12 and 16!!



#15 NicasDream

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Posted 13 December 2023 - 06:50 PM

I'm leaning towards a 18 inch uc obsession for a better balance of fov

Because I like wide angles a lot and also don't want to stand on a step I'm only 6" and I'm 35 years old and 75 pounds sounds better than 95 in 5 years

And my current 12 inch is like 45 pounds and don't mind taking it out every day from my room

And shipping an 18 mirror for recoating seems easier than a 22 inch mirror

But I still don't get how you guys sit while observing those chairs seem really low and annoying XD

I do have a question though if I put a 30mm eyepiece in a F4.2 primary mirror am I going to see the secondary mirror shadow at 7.1 exit pupil?

#16 MeridianStarGazer

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Posted 13 December 2023 - 10:38 PM

I'm leaning towards a 18 inch uc obsession for a better balance of fov

Because I like wide angles a lot and also don't want to stand on a step I'm only 6" and I'm 35 years old and 75 pounds sounds better than 95 in 5 years

And my current 12 inch is like 45 pounds and don't mind taking it out every day from my room

And shipping an 18 mirror for recoating seems easier than a 22 inch mirror

But I still don't get how you guys sit while observing those chairs seem really low and annoying XD

I do have a question though if I put a 30mm eyepiece in a F4.2 primary mirror am I going to see the secondary mirror shadow at 7.1 exit pupil?


To see the shadow, your pupil needs to be close to the size of the shadow, not merely smaller than the exit pupil. No worries at night.

I had not thought of angles at 18" vs 22", but that makes sense. The cost of big aperture. The ladder is a big reason.
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#17 grzesznypl

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Posted 15 December 2023 - 01:29 AM

..... Because like people have said above, there isn't much difference between a 12 and 16!!

Difference between 12" and 16" telescope is 0.6 magnitude and about 77% more light. If anyone does not see that ... well, maybe checkers or hand knitting would be better hobby for this person.


Edited by grzesznypl, 15 December 2023 - 01:30 AM.

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#18 MeridianStarGazer

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Posted 15 December 2023 - 09:38 AM

Difference between 12" and 16" telescope is 0.6 magnitude and about 77% more light. If anyone does not see that ... well, maybe checkers or hand knitting would be better hobby for this person.


Depends on the sky. I saw M13 at a B2 dark site not looking impressive for me in an 18" with 72 degree eyepieces. Different night, different dark site, the view of M13 through a 10" was way better and looked much brighter. Might have also been my level of dark adaptation. Aperture helps side by side but is far from the most important factor.

#19 Waynosworld

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Posted 15 December 2023 - 07:18 PM

Difference between 12" and 16" telescope is 0.6 magnitude and about 77% more light. If anyone does not see that ... well, maybe checkers or hand knitting would be better hobby for this person.

I have said that upgrading from a 12" to a 16" or from a 16" to a 20" was not that dramatic more than once, the difference is not worth an expensive upgrade, spending money for gas to drive to a dark site is a better idea.


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#20 George N

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Posted 16 December 2023 - 10:57 AM

I have said that upgrading from a 12" to a 16" or from a 16" to a 20" was not that dramatic more than once, the difference is not worth an expensive upgrade, spending money for gas to drive to a dark site is a better idea.

I've owned some scopes for 50 years - including a 20-inch Dob for about 25 years (on my 2nd one F/3.5 vs F/5). I spend some nights at Bortle 2 - Cherry Springs, where I have an annual Galaxy Pass (not quite 3-hour drive) - and a 'camp' in the Adirondacks - side-benefit = Bortle 2 / SQM = 21.85.

 

I would agree that a person with a 16" Dob for a year or two should concentrate on just observing - and getting themselves and the Dob to Bortle 3 or better as often as possible.

 

Now let's assume - they already observe often under dark sky - they know 'the drill' with getting the most out of a big Dob - they know what they want to observe, and the 16 is not getting it - an upgrade to a 20 may well be in order.

 

Dramatic increase? That would be going from my friend's 16 or even my 20 to another friend's 36" F/4 with 3-inch ES 30mm 100 eyepiece -- or even Al Nagler's NV device. Now *that's* dramatic!  wink.gif

 

Anyway - I certainly *can* see a difference in the views provided by an excellent 16 and an excellent 20 under Bortle 2 sky. For example - details in the spiral arms of M-51 or M-101 - more seen in the 20. A few months ago at Stellafane 2023 I had my 20 F/3.5, PII, ES 25mm 100 on M-13 and two galaxies - one 9th, one 16.5 magnitude - in one field of view I had - Milky Way field stars - maybe 50 to 1200 light years, M-13 a sea of stars at 22,000 light years, bright galaxy at maybe 30 million light years, dim 16th mag fuzzie at maybe 300 million light years (easy direct object - no averted anything needed to see it). None of the other scopes in the area could provide that view - 12 too small - friend's 20 F/5 with 20mm Nagler - field too small to see all three. Another time - friend with a 22" F/3.6 at Cherry Springs had a list of "billion light year galaxies" - we went hunting with his scope and my 20 F/5 -- while any one the 22 showed was seen in the 20 -- they were just a tad brighter in the 22.

 

As of late I'm liking Mel Bartels recommendation for building (and buying) 'the next Dob' in your yard -- decide on the focal length - then thro money and effort at it to get to the largest primary that will still 'work' (provide a 7mm or 6mm exit pupil - maybe an F/3.0?) - with of course the limitations of $$, ease of use, transport, etc. - but those things differ for each observer.

 

Bottom line - a very good 16" Dob will provide a lifetime of excellent observing for anyone -- but there will always be a few who want more and are willing to spend the $$ and deal with the 'lifestyle changes' needed to make use of it. I expect to see at least one 30", maybe three, on the field at Cherry Springs on any clear weekend night for a long time to come.


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#21 Waynosworld

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Posted 16 December 2023 - 07:33 PM

I've owned some scopes for 50 years - including a 20-inch Dob for about 25 years (on my 2nd one F/3.5 vs F/5). I spend some nights at Bortle 2 - Cherry Springs, where I have an annual Galaxy Pass (not quite 3-hour drive) - and a 'camp' in the Adirondacks - side-benefit = Bortle 2 / SQM = 21.85.

 

I would agree that a person with a 16" Dob for a year or two should concentrate on just observing - and getting themselves and the Dob to Bortle 3 or better as often as possible.

 

Now let's assume - they already observe often under dark sky - they know 'the drill' with getting the most out of a big Dob - they know what they want to observe, and the 16 is not getting it - an upgrade to a 20 may well be in order.

 

Dramatic increase? That would be going from my friend's 16 or even my 20 to another friend's 36" F/4 with 3-inch ES 30mm 100 eyepiece -- or even Al Nagler's NV device. Now *that's* dramatic!  wink.gif

 

Anyway - I certainly *can* see a difference in the views provided by an excellent 16 and an excellent 20 under Bortle 2 sky. For example - details in the spiral arms of M-51 or M-101 - more seen in the 20. A few months ago at Stellafane 2023 I had my 20 F/3.5, PII, ES 25mm 100 on M-13 and two galaxies - one 9th, one 16.5 magnitude - in one field of view I had - Milky Way field stars - maybe 50 to 1200 light years, M-13 a sea of stars at 22,000 light years, bright galaxy at maybe 30 million light years, dim 16th mag fuzzie at maybe 300 million light years (easy direct object - no averted anything needed to see it). None of the other scopes in the area could provide that view - 12 too small - friend's 20 F/5 with 20mm Nagler - field too small to see all three. Another time - friend with a 22" F/3.6 at Cherry Springs had a list of "billion light year galaxies" - we went hunting with his scope and my 20 F/5 -- while any one the 22 showed was seen in the 20 -- they were just a tad brighter in the 22.

 

As of late I'm liking Mel Bartels recommendation for building (and buying) 'the next Dob' in your yard -- decide on the focal length - then thro money and effort at it to get to the largest primary that will still 'work' (provide a 7mm or 6mm exit pupil - maybe an F/3.0?) - with of course the limitations of $$, ease of use, transport, etc. - but those things differ for each observer.

 

Bottom line - a very good 16" Dob will provide a lifetime of excellent observing for anyone -- but there will always be a few who want more and are willing to spend the $$ and deal with the 'lifestyle changes' needed to make use of it. I expect to see at least one 30", maybe three, on the field at Cherry Springs on any clear weekend night for a long time to come.

I used to go to a bortle 3 dark site maybe 3 or 4 times a year(have had SQM 21.62 once), but the road washed out last winter and it has not been rebuilt, this dark site was slightly over 2 hours of driving and it was at 4000'(Johnson Ridge/Mt. St. Hellens), I have never been anywhere else with a telescope that comes close to that place, I have been up Cloud Cap on Mt. Hood(6000'), but that is not the greatest road(it's a very rough road), I do not think I would like to take my 16" travel dob up that road for just a night, I used to fly hanggliders off Surveyors Ridge near Mt. Hood, but the Oregon Forest Service does not service that road anymore, I tried getting up there a couple years ago(last year?) and dented my gas tank trying, I did not make it.

 

I have never spent more than 6 hours at a dark site, my situation does not allow me to be gone longer than that, so my bortle 7+ backyard is where I am 99 percent of the time, and I have had some great nights there since late 2020.


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#22 GeneT

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Posted 16 December 2023 - 08:18 PM

In my experience it is sky conditions and darkness that make the biggest difference.

I took my 6” skywatcher dob to Cherry Springs PA (B2) this past early Summer and observed M97 Owl, M57, M27, CatsEye Nebula, M104 Sombrero Galaxy and a plethora of things in Sagittarius. The transparency was exceptional. The 6” in these conditions significantly out preformed my 10” Dob from home B5 skies.

The most remarkable night of astronomy was observing from high altitude in Utah B1. I was in my mid-20s and had a Astroscan 4.25” (redball scope) running through the spring galaxy clusters was unbelievable. The contrast on M64 (Blackeye galaxy) was picture like. I have not been able to duplicate that experience since. Even with 10” and in B2 conditions.

A good 8” and the ability to get to dark skies regularly beat a 20” from lesser skies IMO (I have looked through up to 25” dobs) Now of course a 20+ from those same skies wound crazy good but at less FOV and much more hassle.

I am currently taking ownership of a 15” dob while I am still fit and healthy but I know when the newness wears out it will be much harder to get motivated to take it out regularly. I’ll still keep my 6” and 8” SCT GnGoes.

Here is what 6-8” can do from dark skies!

https://www.deepskyw...o-sketches.html

Outstanding drawings!


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#23 George N

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Posted 17 December 2023 - 11:40 AM

I used to go to a bortle 3 dark site maybe 3 or 4 times a year(have had SQM 21.62 once), but .......

.....

I have never spent more than 6 hours at a dark site, my situation does not allow me to be gone longer than that, so my bortle 7+ backyard is where I am 99 percent of the time, and I have had some great nights there since late 2020.

Well - "....using it 99% of the time in my back yard...." - at least you don't have to worry about having a vehicle large enough to transport your telescope - you just need to fit it thru the door of your house or storage location.

 

Alas, "light pollution" continues to have a major impact on 'the hobby' - and equipment decisions. Since 'Light Pollution' mostly tracks 'population density' - it all becomes part of a 'lifestyle decision', of which 'hobby astronomy' tends to be minor part.

 

If factors such as $$, observer health, ease of move from storage to observing site allow - a 20" will still provide 'more' to the visual observer than a 16 even under SQM = 18.00 -- but a 16 is a very fine instrument. Some suggest NV as a 'solution' -- and they may be right. I'd advise that they not look thru Al Nagler's NV attached to a 36" F/4 under Bortle 2 sky.

 

Nobody has covered the other OP question - Hubble Optics vs Explore Scientific Dobs. I've looked thru a sample of each - but that's too little experience to have any real opinion. The views thru both were 'nice'.


Edited by George N, 17 December 2023 - 11:41 AM.

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#24 grzesznypl

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Posted 17 December 2023 - 12:30 PM

All of these things on my wish list are pointing me towards the HO UL20 in the 3.7. Does anyone have one of these and would you recommend it (or not)?


Another thing I hate to tell you but many people looking for advise with UL20 have same problem like you. There are not many of those telescopes around. In the last 3 years there was only one sold on CN in Apr 2022. After short poking around CN I found those threads that will be a great interest to you:

- Unboxing my 24" Hubble optics Dobsonian - OP owns of both 24" and 16" Hubble Optics telescopes. He could be great source of info for your needs. 
 
Thoughts on my 20” f/3.3 Telescope - OP has telescope with HO 20” f/3.3 mirror.
 
Hubble Optics UL20 F/3.7

Other related: 
 
Hubble Optics Ultra Light 20" Dob
- 20" Hubble optics UL new version
Hubble optics UL20?
- Hubble 20" Premium Ultra Light Dobsonian Telescope
Review of the Hubble Optics 14 inch, f/4.6 Premium Ultra Light Dobsonian Telescope


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#25 MeridianStarGazer

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Posted 17 December 2023 - 02:38 PM

When not many are for sale used, is that because not many were sold new, or because most buyers refuse to sell theirs?

Edited by MeridianStarGazer, 17 December 2023 - 11:25 PM.

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