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Aperture Fever? 8" vs 10" or 12"

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#26 Asbytec

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Posted 25 January 2019 - 11:11 PM

If a scope is too big or too awkward, it's unlikely to get much use. .

Jon

There is some truth to the saying that a scope being used is the best scope. Ergonomics such as set up, eyepeice height, comfort, and ease of operation is one (or many?) of the reasons a scope gets used. A lot.

My no frills 6" CAT is much simpler than my previous C11. I am often amazed how quickly I am seated comfortably and observing in such short order. For that reason, one of them anyway, my 6" gets used a lot. No regrets. Well, a little...but, thus far, the 6" is still my most used scope. Primarily because of ergonomics.

My solid tube 12" Dob rearranged the pictures on my wall when taking it down the hall and out the door. I'm half kidding. Sometimes I bang the 8" solid tube focuser on the door jam. Not kidding. :)

Edited by Asbytec, 25 January 2019 - 11:14 PM.

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#27 stargazer193857

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Posted 25 January 2019 - 11:14 PM

A faster mirror gives lower seats, wider view, same aperture. But at cost of more coma and more fabrication challenge. The wave error needs to be less to do as well at the same magnification and smaller eyepiece, but this most be done with a less spherical mirror.


A 10" of equality costs less than a 12".

#28 stargazer193857

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Posted 25 January 2019 - 11:16 PM

If a dob will take an hour to cool, then what is 15 minutes to set up?

#29 Jon Isaacs

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Posted 25 January 2019 - 11:25 PM

If a dob will take an hour to cool, then what is 15 minutes to set up?

 

A scope that's cooling can be used,  a scope that's cooling can be left alone while it cools. 

 

Jon



#30 Asbytec

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Posted 25 January 2019 - 11:27 PM

If a dob will take an hour to cool, then what is 15 minutes to set up?

Good point. I guess it depends on when and how you cool it. In a modest climate, mine is usually cooled pretty well for an hour or two before it goes outside. It cools a little more as night sets in and ambient drops a bit, but I observe with it anyway. I just avoid double stars until it is more thermally stable and the seeing cooperates. Some folks set up well before dark. As seemingly always, YMMV, depending on observing conditions and a set up and cooling technique that work well enough. I like the quick set up (and tear down), regardless. 


Edited by Asbytec, 25 January 2019 - 11:29 PM.


#31 stargazer193857

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Posted 26 January 2019 - 12:19 AM

A 12" f5 is better for people who like to stand. But far from ideal for them. A 10" f5 is great for a short person with a simple chair. A tall person may prefer sitting with the 12" at zenith, but will still need an adjustable chair for lower stuff.
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#32 CrazyPanda

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Posted 26 January 2019 - 03:25 AM

I love my Sky-Watcher Collapsible 8" Dobson...but I am just wondering about stepping up to a 10" or 12 " Dobson in the future.  I primarily enjoy lunar and DSO viewing...and was looking at possibly upgrading to either the Explore Scientific 10" Truss Dob or 12" Truss Dob.  Both weigh about the same as my Sky-Watcher 8".  Is the WOW factor for visual viewing worth the upgrade?  All scopes are f/5. 

I went from 8 to 12 and it's a big, big difference. 

 

While I got a lot of use out of my 8", the 12" opened up a new world of high power planetary nebulae observing, and revealing more detail and structure in galaxies. 


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#33 mikeDnight

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Posted 26 January 2019 - 04:35 AM

I love my Sky-Watcher Collapsible 8" Dobson...but I am just wondering about stepping up to a 10" or 12 " Dobson in the future.  I primarily enjoy lunar and DSO viewing...and was looking at possibly upgrading to either the Explore Scientific 10" Truss Dob or 12" Truss Dob.  Both weigh about the same as my Sky-Watcher 8".  Is the WOW factor for visual viewing worth the upgrade?  All scopes are f/5. 

I remember an account told by Harold Hill, an esteemed British lunar observer, when he had chance to compare his old 6.25" reflector with his 10" F10. Although the detail in the 10" was much brighter, Harold admitted that everything visible in the 10" was also visible in the 6.25". I suppose this illustrates just how powerful a tool a 6" Newtonian really is. It also begs the question "Is the increase in size, and the more cumbersomeness of the larger scope, going to enhance your over all enjoyment of lunar observing? Or is it going to put you off?

May be the 8" used with a binoviewer would be the best way to go as far as lunar & planetary observing goes!?



#34 CrazyPanda

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Posted 26 January 2019 - 04:39 AM

May be the 8" used with a binoviewer would be the best way to go as far as lunar & planetary observing goes!?

 

This might depend. I see *less* detail through my binoviewer than I do monoviewing, and it requires exceptionally steady seeing to even come close to monoviewing for me for reasons I haven't quite figured out yet. Optics are not the problem. It's a properly collimated Zeiss binoviewer with Zeiss eyepieces. 

 

If I can catch glimpses of high detail in pickering 6 seeing when monoviewing, I need at least pickering 8 seeing in the binoviewer to see the same detail.


Edited by CrazyPanda, 26 January 2019 - 04:41 AM.


#35 Jon Isaacs

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Posted 26 January 2019 - 04:44 AM

I remember an account told by Harold Hill, an esteemed British lunar observer, when he had chance to compare his old 6.25" reflector with his 10" F10. Although the detail in the 10" was much brighter, Harold admitted that everything visible in the 10" was also visible in the 6.25". I suppose this illustrates just how powerful a tool a 6" Newtonian really is. It also begs the question "Is the increase in size, and the more cumbersomeness of the larger scope, going to enhance your over all enjoyment of lunar observing? Or is it going to put you off?

May be the 8" used with a binoviewer would be the best way to go as far as lunar & planetary observing goes!?

 

Lunar observing is primarily about seeing and thermal equilibrium.  Deep sky is quite different.. 

 

Jon


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#36 clivemilne

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Posted 26 January 2019 - 05:22 AM

16" is entry level interesting imho)



#37 phillip

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Posted 26 January 2019 - 06:05 AM

Aperature is definitely the name of the game.

My current use is the smaller XT8 tho have a XT10 and 12 inch lightbridge.

Actually made a video of fast setup and tear down with the XT8. Tho scope setting by trunk,

The mount was door closed in back seat. After setup even planting eyepiece, tear down then
mount back in car, total
Time under 2 minutes!

A reviewer responded, I was wanting to see exactly this, then promptly had one on

Order!

If I was younger likely be looking at the 14 inch !


ETX90, 4SE
XT8I, XT10
Eypiece Clave 8mm planet looks

Edited by phillip, 26 January 2019 - 06:12 AM.


#38 gwlee

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Posted 26 January 2019 - 06:11 AM

If you could have a 10" that is 30 pounds, would you switch to that from the 8"? 

Anyone here stayed inside on a good night because you did not feel like taking out an 8"?

I have owned several 8” inch scopes over the years because they offered a balance between optical performance and portability that was well suited to my observing site. At other sites, my present site for example, they were too heavy and bulky to be satisfactory, so I eventually replaced them with a smaller telescope more suited to the site and used a bino until then rather than miss an observing opportunity. 

 

So far, my experiments buying an ultralight 8” scopes or lightening an 8” factory scope haven’t turned out well. I found that reducing the weight of a scope is EASY, but doing so without introducing other serious problems is difficult, which is one reason mainstream scopes weigh what they do.

 

So, if someone offered me a 30# 10” Dob, I would be more than a little skeptical about its performance, and wouldn’t consider buying it without doing a thorough hands-on evaluation first. 


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#39 25585

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Posted 26 January 2019 - 03:22 PM

Viewing comfort has become important as I grow older. But so are memories. I will be back to 8 then 6 inches eventually, but like to keep the scopes of my youth to aid as memory joggers. 



#40 stargazer193857

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Posted 26 January 2019 - 06:33 PM

I have owned several 8” inch scopes over the years because they offered a balance between optical performance and portability that was well suited to my observing site. At other sites, my present site for example, they were too heavy and bulky to be satisfactory, so I eventually replaced them with a smaller telescope more suited to the site and used a bino until then rather than miss an observing opportunity.

So far, my experiments buying an ultralight 8” scopes or lightening an 8” factory scope haven’t turned out well. I found that reducing the weight of a scope is EASY, but doing so without introducing other serious problems is difficult, which is one reason mainstream scopes weigh what they do.

So, if someone offered me a 30# 10” Dob, I would be more than a little skeptical about its performance, and wouldn’t consider buying it without doing a thorough hands-on evaluation first.


Nice to know. What sort of problems did the light weight ones have? Would you need to inspect it yourself if a big name poster did so first?

#41 stargazer193857

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Posted 26 January 2019 - 06:33 PM

Viewing comfort has become important as I grow older. But so are memories. I will be back to 8 then 6 inches eventually, but like to keep the scopes of my youth to aid as memory joggers.


What size scopes give you your best memories?

#42 17.5Dob

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Posted 26 January 2019 - 08:00 PM

No point in going from an 8-10". Going from an 8" to 12" will definitely be an improvement, but I feel you really need to step up to a 16" + to really see a difference.


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#43 Jon Isaacs

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Posted 26 January 2019 - 08:42 PM

No point in going from an 8-10". Going from an 8" to 12" will definitely be an improvement, but I feel you really need to step up to a 16" + to really see a difference.

 

I really see a real difference going from a 10 inch to a 12.5 inch or a 13.1 inch.  That's about 0.5 magnitudes and 0.6 magnitudes.  Going from an 8 inch to 12 inch is about 0.9 magnitudes, to a 12.5 inch is a 1.0 magnitudes.  Those are major differences.  

 

If one is looking for a WOW, there is really no scope that will ever be big enough, the WOW wears off and it's on to a bigger scope.  That's aperture fever, fueled by dissatisfaction.  Going from an 8 inch to a 12 inch, that's big jump in capability.  When that WOW wears off, that's when you can get down to business and start really observing and taking advantage of the greater capability.

 

Jon


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#44 Asbytec

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Posted 26 January 2019 - 08:46 PM

That's aperture fever, fueled by dissatisfaction.  

 

Jon

So true on so many levels. I feel a dissertation coming on, but it's easy to resist. My morning coffee is cold. smile.gif


Edited by Asbytec, 26 January 2019 - 08:48 PM.

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#45 Jond105

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Posted 26 January 2019 - 08:55 PM

 

When that WOW wears off, that's when you can get down to business and start really observing and taking advantage of the greater capability.

 

Jon

Yup. Trust me when I say there was huge wow going from 120mm to 10". Probably not as huge as 8" to 10". I also think I wouldn't use the 12" though if I couldn't bring it out at a moments notice in one piece. 

 

With what Jon said, If you're like me, that's when you start looking for things to improve those observing sessions with the gear you have. 


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#46 Asbytec

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Posted 26 January 2019 - 09:34 PM

With what Jon said, If you're like me, that's when you start looking for things to improve those observing sessions with the gear you have.

Yes. I understand the WOW factor with aperture. I also understand the WOW factor of seeing anything in the aperture and gear we do have. In some ways, pressing our aperture, observing conditions, and skill into service offers an amount of personal satisfaction. It's that personal satisfaction and achievement that offers it's own WOW factor.

For example, I may not see a spiral arm, but I may see enough hints within that faint fuzzy to know it's there. I may not see a spiral arm, but I might see a stellar nucleus and a mottled core. That's something, that's what the galaxy looks like. That's amazing in and of itself.

I am pleased to have made anything of it because I worked hard to do so. When effort pays off, we cannot deny ourselves the pleasure of being satisfied. I think that's true across all apertures and types. Its simply a matter of cosmic depth and scale.

Once you get there, the desire for larger aperture seems to be driven less by fever and dissatisfaction, and it is more a decision made with reason. Aperture can certainly make some challenges easier, but it also opens up new ones on the frontier of that aperture. I guess it's the desire for new challenges that justifies larger aperture, not so much disappointment with smaller ones.

Edited by Asbytec, 26 January 2019 - 11:12 PM.

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#47 Jon Isaacs

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Posted 27 January 2019 - 06:13 AM

Once you get there, the desire for larger aperture seems to be driven less by fever and dissatisfaction, and it is more a decision made with reason. Aperture can certainly make some challenges easier, but it also opens up new ones on the frontier of that aperture. I guess it's the desire for new challenges that justifies larger aperture, not so much disappointment with smaller ones.

 

waytogo.gif

 

Satisfaction versus Dissatisfaction .  I've never upsized because i was dissatisfied with the views I was seeing . Rather , it was the combination of being satisfied along with opportunity.

 

In 2010, my wife and had purchased our high desert hideaway the previous year and I was having great fun with my refractors and my 12.5 inch and 16 inch Dobs .

 

It took a while as I had never thought about owning a 20 inch plus scope but I after a while , I realized that I was in an ideal situation to take advantage of a very large scope.  Clear , reasonably dark skies,  a large garage where the scope could be permanently left assembled, it seemed like a big scope would fit nicely .

 

So I decided to keep my eye open for a reasonably priced , large Dob . If one came along, that would be nice,  if one didn't that was fine too. 

 

One did .

 

For me,  I spend enough time observing , last year about 160 nights last year for about 500 hours , that it does come down to the new challenges , pushing the limits.  The showcase objects are great in a large scope but most of my time is spent on small , difficult objects , pushing the limits of perception .

 

Greg LeMond won the Tour de France 3 times.  He once said ;

 

"It never gets any easier,  you just go faster ."

 

I like that . In terms of large scopes , "It never gets any easier , the objects are just smaller and fainter .

 

Jon


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#48 Asbytec

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Posted 27 January 2019 - 07:16 AM

waytogo.gif

 

Satisfaction versus Dissatisfaction .  I've never upsized because i was dissatisfied with the views I was seeing . Rather , it was the combination of being satisfied along with opportunity.

 

You do seem to take good advantage of opportunities. 

 

I spent a lot of time drooling over ads for this or that scope, a nebular filter or a set of them, focal reducers, vibration suppression pads, GOTO...you name it. Had most of it at one time or another, including an 18" Dob (I wish I still had). Always looking for ways to see more, but was never satisfied. Until I realized it was me, as an observer I am the one crucial accessory being overlooked all of those years. After realizing that, I became the same way...never dissatisfied. Except with LP for faint fuzzies, so I moved. 


Edited by Asbytec, 27 January 2019 - 07:18 AM.

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#49 sickfish

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Posted 27 January 2019 - 08:17 AM

I have had my XT8 for some years now. This year I will be adding a 12" to my brood.

I will keep the 8, I am building a new base for it now. I love that scope.


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#50 25585

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Posted 27 January 2019 - 09:07 AM

What size scopes give you your best memories?

My 12 inch F5 with which, as it was my first Dob, I really delved into deep sky, why I still have one. With it I could use an OIII filter and still see stars. The 8 was better with UHC as less dark.

 

I "discovered" how 4 inches more of mirror gave a much better light show than the 8 inch, and star hopping was easier as more asterisms were visible - much more than Sky Atlas 2000 charted, Uranometria 2000 detail was closer. The 12 got me hooked. Its price was not much more than a 10.

M57, M13, M31, Pleiades, Orion were fantastic. Double stars. All were easy. But seeing with direct vision, what was just possible with averted before, was the best

 

With a heavier scope, it was better with heavy eyepieces, and when I had a Nagler 13mm original, only a small counter balance weight was needed, the mirror weight did the rest. I stopped at 12 inches due to handling and storage considerations, also my nice country road got street lighting and neigbours badly pointed backyard lights required moving my scope around to avoid them.

 

I can just get the 12 in my car, but the 10 F5 is easier, and I can take it to dark sites which counts for a lot. Keeping with solid tubes as they are good accessory platforms - Telrad, finders, handles, weight fixing and general protection.


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