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How much increase in aperture to see a difference?

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#101 JimP

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Posted 10 June 2017 - 07:39 AM

I agree with you with one exception.
There is a need, at least for me and I believe for many others, to be afraid of chasing aperture. I remember when I first looked through my RV-6, a 6 inch F8 Newtonian from Criterion I purchased in the late 1960s. My first view of Jupiter through it was awesome! I still have my journal with drawings in it using that telescope. So, what were my first thoughts after looking at Jupiter that first night? "Wow, if a six-inch can show detail on Jupiter like that, think about what an 8 inch or 10 inch or.. will show. I had hardly finished observing before I was already interested in moving up in aperture. Not being satisfied with what you have and being obsessed with increasing aperture can be a huge distraction and, for me, a real problem.
After 50 years of observing, after using Newtonian Reflectors, Schmidt-Cassegrainds, Maksutovs and Refractors, I developed a primary interested in observing the moon, planets and double stars. I concluded that, for me, there was not a need for aperture over about 8 inches and absolutely no desire for a scope requiring collimation. Refractors and Maksutovs do everything I need and without worrying about collimating or what a scope with more aperture than what I own might show.
It took a long time, often learning the hard way, buying scopes with huge aperture only to end up dissatisfied, to come to the conclusions I have and I am happy to have dropped out of the aperture race.


Edited by JimP, 10 June 2017 - 07:43 AM.

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#102 Gofr

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Posted 10 June 2017 - 08:52 AM

I agree with you with one exception.
There is a need, at least for me and I believe for many others, to be afraid of chasing aperture. I remember when I first looked through my RV-6, a 6 inch F8 Newtonian from Criterion I purchased in the late 1960s. My first view of Jupiter through it was awesome! I still have my journal with drawings in it using that telescope. So, what were my first thoughts after looking at Jupiter that first night? "Wow, if a six-inch can show detail on Jupiter like that, think about what an 8 inch or 10 inch or.. will show. I had hardly finished observing before I was already interested in moving up in aperture. Not being satisfied with what you have and being obsessed with increasing aperture can be a huge distraction and, for me, a real problem.
After 50 years of observing, after using Newtonian Reflectors, Schmidt-Cassegrainds, Maksutovs and Refractors, I developed a primary interested in observing the moon, planets and double stars. I concluded that, for me, there was not a need for aperture over about 8 inches and absolutely no desire for a scope requiring collimation. Refractors and Maksutovs do everything I need and without worrying about collimating or what a scope with more aperture than what I own might show.
It took a long time, often learning the hard way, buying scopes with huge aperture only to end up dissatisfied, to come to the conclusions I have and I am happy to have dropped out of the aperture race.

I'm only a year and half in, but I have already, at least at this time, come to a very similar conclusion. I want as little collimation as possible and most of my viewing interest does lie with doubles and solar system objects. When looking to upgrade from my 90mm refractor, I was constantly looking over at the larger maks, namely the SW180, as my upgrade. I eventually encountered a used C9 for a very decent price that I couldn't pass up on and went that way instead, trusting the more experienced observers' advice that SCT collimation is super simple (as compared to a newt). Indeed I did find SCT collimation to be a super simple matter. Plus, the C9 is the biggest aperture I'd probably ever want on my current mount, and I have no desire for larger mounts (or dobs).

 

For now the C9 will be my primary scope, but over the years I hope for it to become more of a deep space tool (even though my interest is doubles and solar system, I'm still new at this and do desire to peek at the deep space stuff....whenever I can escape my light polluted city yard) and to upgrade my 90mm into maybe a nice 100mm and at some point do also a nice 6 inch refractor. One day.

 

Point is, I already feel I'm at the largest aperture or at least very close to the largest I would ever want. I'm not even sure my area has the best conditions to max out my C9 regularly. Anything larger would probably only be a waste of time, energy, and resources. Now about getting a Herschel wedge for my 90mm for these lovely sunny summer days...


Edited by Gofr, 10 June 2017 - 08:55 AM.


#103 Jon Isaacs

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Posted 10 June 2017 - 09:57 AM

Not being satisfied with what you have and being obsessed with increasing aperture can be a huge distraction and, for me, a real problem.

 

 

waytogo.gif

 

Jim:

 

This exact phenomenon is what I identify as "aperture fever" and I see it happening to people here.  When it's obsessive and takes away from from the enjoyment and appreciation of ones current scopes, I see it as detrimental and figure it's likely that individual will soon move on to another hobby.. 

 

The thrills in amateur astronomy are subtle, the BIG WOW of first light with a bigger scope can be addictive. Once the cheap thrills are gone, rather than settling in and really learning how to observe,  it's thinking about the next scope. 

 

I think there's a fine line between aperture fever and a more rational approach to choosing equipment.  In my mind the reason to choose a larger scope is because one is satisfied with ones current scope and just wants more capability.  

 

For me,  that's how it has been. Just a sense that if the opportunity arose,  the right scope at the right price, it could workout.  But I never thought about it while I was observing, the thought that I wanted,  desired,  had to have a bigger scope,  never came into my mind while I was actually out under the stars, I was too engaged,  having too much fun,  too much in the moment.  

 

I can imagine how someone looking through their telescope might be frustrated and disappointed and unable to enjoy what equipment they do have..  That never really happen to me.  If you saw the first scope I had,  a wornout 60 mm refractor with one two element eyepiece, no finder,  all strapped to a department store tripod,  it would be hard to imagine I wasn't frustrated and itching for a new scope but that didn't happen,  I had no expectations and was just happy to be looking through a telescope.. 

 

I guess one sign of satisfaction..  I keep scopes.  When I bought my 25 inch,  it wasn't like I was going to get rid of my smaller Scopes, they all have their place. 

 

If one is in this thing for the long haul,  finding what one enjoys,  finding the equipment that let's one observe the way one enjoys observing,  these are the two most important things. You've found what works for you,  I've found what works for..  How good is that? 

Jon


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#104 Scott99

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Posted 10 June 2017 - 10:21 AM

It took a long time, often learning the hard way, buying scopes with huge aperture only to end up dissatisfied, to come to the conclusions I have and I am happy to have dropped out of the aperture race.

dropped out?  I would say you've WON the refractor aperture race. lol.gif lol.gif waytogo.gif


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#105 fishhuntmike

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Posted 10 June 2017 - 10:24 AM

Ive been contemplating the same thing having an ap130, wondering if a 180/185 would be my ultimate setup or even a 160. I have only one equatorial mount (g11) which i use for both the 130 and C14 (the mount is over 20 years old, as is the C14). I am yearning for more saturated views of the planets than my 130 provides and my C14 gives that but does not give me what im after due to my seeing and thermal issues.

I have a 6" f15 on a Berry mount that gives the refractor (pristine) views im looking for on dso's and the moon but has a little too much CA on jupiter for my liking and is still just a little weak on dso's. Hence my desire for something like a 7".

As luck would have it, the Berry mount i built for my inexpensive 6" f15 lens will work perfectly for my (hopefully) 8" f12 D&G that was ordered exactly 3 years ago this month. I expect that i will get the refractor dso views im am looking for with that scope, if i get it some day. Because of this i will not get a 7" apo refractor.

Back to the C14. Im considering a big Dob. But im also considering a better mount with goto like an AP mach1, and just living with the views of the C14 and forgetting about jumping to a 16", 18", or even 20.

I think having an awesome mount that could help me find faint objects with the c14 and also allow the opportuning for astrophotography in the future (with the ap130) might be a wiser choice for me personally.

Planets are not my favorite objects, but if they were i might consider ordering a premium 10" mirror and building a wood planetary newtonian, fans and all to use on my G11.

Cant wait to hear what your ultimate decision will be

#106 Jared

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Posted 10 June 2017 - 10:53 AM

Personally, I don't see the jump from 130 to 140 as being "worth it" meaning I wouldn't change if I already owned a 130 that I liked. Jumping from 130 to 150+ is "worth it" meaning you will see an obvious, though perhaps not spectacular, jump in light grasp. You will also see an obvious difference in resolution on nights or locations with above average seeing.

That being said, some years ago I actually went from a 110mm to a 152mm scope, then decided to "downgrade" to a 130mm as my main, portable refractor. Even though my mount could easily handle the weight of the 152 it was too big to be fun to pack up, carry down 30 stars to the car, load, unload again, carry another 50 yards in 4 trips to my most common observing site, and setup again. I wouldn't take the scope out on marginal nights--I would stay in instead. Not good. After downgrading to a 130 I found my observing sessions were once again more numerous.

Every person's requirements are a bit different, but chasing aperture fever can be a mistake. I find a 130mm (or a 140mm if I were starting from scratch) to be the best compromise if transport is going to be common. Much more satisfying than a 100mm or 110mm without turning into a beast I don't want to carry. Personally, even though it's not fun for me to say or for you to hear, I'd recommend standing pat. Not enough of a jump from 130 to 140, and while I'd love to have a 150 to 160 class instrument again I'd only consider it as an addition to my 130, not as a replacement. If I had an observatory or a site where I could leave the scope setup I'd take a 160 in a heartbeat.

Edited by Jared, 10 June 2017 - 10:56 AM.

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#107 JimP

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Posted 10 June 2017 - 02:18 PM


 

I can imagine how someone looking through their telescope might be frustrated and disappointed and unable to enjoy what equipment they do have..  That never really happen to me.  If you saw the first scope I had,  a wornout 60 mm refractor with one two element eyepiece, no finder,  all strapped to a department store tripod,  it would be hard to imagine I wasn't frustrated and itching for a new scope but that didn't happen,  I had no expectations and was just happy to be looking through a telescope.. 

 

I guess one sign of satisfaction..  I keep scopes.  When I bought my 25 inch,  it wasn't like I was going to get rid of my smaller Scopes, they all have their place. 

 

If one is in this thing for the long haul,  finding what one enjoys,  finding the equipment that let's one observe the way one enjoys observing,  these are the two most important things. You've found what works for you,  I've found what works for..  How good is that? 

Jon

 

 

Wonderful!

 

My first scope was a Gilbert 80X. About a 60mm reflector that cost $20. Given to me by my Mom for my 15th birthday in 1965. I actually have a notebook I filled with observations with that scope. Somewhere along the way I misplaced the scope but I have another just like it on a shelf in my observatory!


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#108 Redbetter

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Posted 10 June 2017 - 03:19 PM

The bottom line is the difference in seeing from a good night and a bad night will have a greater effect on planetary detail observed than the difference in aperture will provide, which will be noticeable only if they are set up side by side on a very good night.  You only gain additional planetary detail when seeing is above the threshold for that aperture, which at 5-6 inches, is pretty high in my experience.  Those who live in a place with excellent seeing on a regular basis will get more benefit out of a larger aperture than those who live in places with more average seeing.

 

Having some experience setting up various apertures next to one on another from 80mm to 20", I can say that the bolded above is not really true in general.  (If applied to a 10mm difference alone in small aperture then it will be closer--and that might have been the thrust of the post.)   I have yet to have a "very good night" for planetary on this side of the Sierra (not a single 500x planetary night so far), yet the differences in aperture are apparent at every increment.  Even in 4/10 seeing (rated in the 110mm) there is noticeable difference in the views and the amount of detail that can be detected. 

 

The seeing only makes a difference up to a point.  Yes, it degrades the view in the scopes and smaller details disappear.  But those smaller details either were never visible in the smaller apertures, or disappear first in them.  The smaller scopes top out sooner so for them seeing has less total impact--although as seeing improves finer details improve at the same magnification levels in the smaller scopes.  But there is an erroneous belief that if the detail level is capped at X for a small scope by the seeing, then it will be capped at X for larger scopes as well.  It doesn't quite work that way.  What is most noticeable is how much more detail is available in 8" or 10" or 20" than in 80mm or 110mm when the seeing steadies for a fraction of a second, even as it begins to drift away again.  There is not much need to chase best focus with the smaller aperture, and more so as the aperture increases, but there are rewards for doing so.  


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#109 Skittersqueek

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Posted 10 June 2017 - 04:15 PM

Hey all! 

 

I was obsessed with those big Aperture Refractors as I wanted more than my 100mm APM Binos could deliver! But getting into the 180mm realm was a little much so I did the next best thing I could think of and just made a binoscope out of two 140mm TEC's.

 

 

So my question I want to know and will have to wait until I find someone with a 180mm refractor, how close does the 140mm Triplet Bino fair against it's bigger brother?

 

 

 

Anyone have experience in that area? What am I gaining? 

 

 

 

Thanks! 



#110 donlism

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Posted 10 June 2017 - 04:21 PM

Just parenthetically off-topic...  I've been reading a book about the Palomar 200".  After the 100" at Mt. Wilson, Hale was wondering what to do next, i.e., how much bigger would it have to be to make a difference, and proposed "200 inches or even 25 feet" (300 inches).  They seriously looked at 300, and realized it would not be possible to get it over roads or through railway tunnels or up the mountain roads.  So do it all on top of the mountain -- haul huge quantities of stuff up there, build the glass foundary, the optical shop, and deal with all the glass- and mirror-making issues up there in the wilderness.  A hugely difficult and expensive undertaking, just not feasible.

 

So...  a new definition of "grab and go," I guess, is to keep it small and simple -- at 200 inches.  That'll do 'er!


Edited by donlism, 10 June 2017 - 04:22 PM.

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#111 Redbetter

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Posted 10 June 2017 - 04:41 PM

Chasing aperture in good refractors gets prohibitively expensive in a hurry from what I can tell.  In Dobs, not so much.  Whether one goes refractor, Dob, both, or some other direction it comes down to ergonomics/convenience weighed against what an aperture in a given type can show and the price to achieve it.  Aperture fever is buying/wanting more than you can actually use or afford (or perhaps more than you want to use on a regular basis.)

 

Choose the scope that fits your needs and make the most of it.  That is what I did when I started with an 8" SCT.  It is what I did when I added the 20" seven years later.

 

Having two or more scopes makes these sorts of things easier.  A grab and go backyard set up that can be moved around quickly is useful.  Take the 80ED I added this winter, it goes out as a scout.   If there is time and conditions look favorable it can call its bigger friends out to play.  That can be the 110 refractor, the 10" Dob, or even the 20" Dob if it is ready to roll out rather than packed up for dark site travel.  The view through each of the larger scopes is incrementally better for planets in town.  However, if it is windy the 110 on a sturdier mount is often best because it tracks, will shake less from the wind (even compared to the 80 on a light alt/az tripod) and the seeing will be limited by the wind as well, so there isn't as much to miss about larger aperture in such conditions.

 

If you have been observing awhile and already know what sites and events you would carry a scope to, and how frequently, then you should have a pretty good idea of what size/bulk/weight/set up time is manageable for you vs. what you will be inclined to make excuses for not using. 


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#112 JimP

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Posted 10 June 2017 - 05:52 PM

Aperture fever is an obsession  with aperture, never being satisfied with whatever aperture you are using, always wanting more.


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#113 MSWcdavis

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Posted 11 June 2017 - 07:20 AM

in a refractor:

 

people talk about 102 to 127 being a reasonable upgrade

 

what about 102 to 115?

 

i would think marginal at best?

 

115 is a nice balance between tube size / tube length....and aperture

 

127 are big boys in terms of mounting requirements

 

115 worth an upgrade over 102? 

 

shocked.gif



#114 Jon Isaacs

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Posted 11 June 2017 - 08:22 AM

in a refractor:

 

people talk about 102 to 127 being a reasonable upgrade

 

what about 102 to 115?

 

i would think marginal at best?

 

115 is a nice balance between tube size / tube length....and aperture

 

127 are big boys in terms of mounting requirements

 

115 worth an upgrade over 102? 

 

shocked.gif

 

I do not consider increasing the aperture of a scope necessarily an upgrade, it's just a different tool..   That said:

 

I consider the step up in aperture from my 4 inch F/5.4 NP-101 to the 120mm Orion Eon worthwhile.  The Eon will split closer doubles, it will provide more detailed planetary views.   It's bigger but not too big to be one trip out the door scope.  

 

Jon


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#115 Jeff B

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Posted 11 June 2017 - 08:47 AM

You're up early Jon. 



#116 MSWcdavis

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Posted 11 June 2017 - 08:47 AM

 

in a refractor:

 

people talk about 102 to 127 being a reasonable upgrade

 

what about 102 to 115?

 

i would think marginal at best?

 

115 is a nice balance between tube size / tube length....and aperture

 

127 are big boys in terms of mounting requirements

 

115 worth an upgrade over 102? 

 

shocked.gif

 

I do not consider increasing the aperture of a scope necessarily an upgrade, it's just a different tool..   That said:

 

I consider the step up in aperture from my 4 inch F/5.4 NP-101 to the 120mm Orion Eon worthwhile.  The Eon will split closer doubles, it will provide more detailed planetary views.   It's bigger but not too big to be one trip out the door scope.  

 

Jon

 

 

in this case i would be selling a very capable 4 inch triplet to fund the 115 f/7

 

i like the idea of the 115 because it seems to be about the max of what my alt az mount (and I) can handle 

 

and i like the focal length being pretty short

 

i don't like long tubes

 

so all tradeoffs considered im not sure if it is worth the effort 

 

i don't like overlap and really only want 3 telescopes at a time (refractor capable of 3 degrees with 30mm 82, 12 inch dob, and solar scope) until such a time as i can reasonably store and wheel a massive dob out of a shed (in blue or darker skies)


Edited by MSWcdavis, 11 June 2017 - 08:49 AM.


#117 Jon Isaacs

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Posted 11 June 2017 - 10:39 AM

in this case i would be selling a very capable 4 inch triplet to fund the 115 f/7

i like the idea of the 115 because it seems to be about the max of what my alt az mount (and I) can handle

and i like the focal length being pretty short

i don't like long tubes

so all tradeoffs considered im not sure if it is worth the effort

i don't like overlap and really only want 3 telescopes at a time (refractor capable of 3 degrees with 30mm 82, 12 inch dob, and solar scope) until such a time as i can reasonably store and wheel a massive dob out of a shed (in blue or darker skies)

 

 

I am not sure it's worth it either..  I enjoy the 120mm but I also know if I were to trim the collection , the 4 inch TV would stay and the 120 would go,  in part because the 4 inch is a better companion for a Dob. 

 

Jon



#118 Binosaurus

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Posted 02 July 2017 - 10:22 PM

 

If only going 10mm (all of 1cm lol), it's not noticeable.

 

Personally, I can't see the hooplah everyone raves about going from a 4" to a 5", but there ya go - some think it is, some don't.

 

Lewis, FWIW, I completely agree with you, after owning quite a few premium 4" and 5" refractors. There is a difference, but in many cases--not all--it is subtle. I think part of the reason you hear so much raving between these two sizes in particular is self-interest. A 5" is really about the upper limit that many people can comfortable afford, mount--and--is readily available. There is a certain smugness to that in comparison to the "lowly" 4"...which itself was considered a "medium sized" refractor two decades ago [an article from an early 1990s Astronomy magazine comes to mind that reviewed "medium size" refractors--all around 4"--including a Genesis, SPC-102F, AP, and I believe the blue 94mm Brandon Christian-sourced triplet]. Now 4" is considered small and 5" is medium. 6" is large in refractorland. If we do end up getting more supply of 6" refractors on the market, I would not be surprised if the supposed big gap in improvement shifts to 5" to 6" rather than the currently held 4" to 5".

 

That being said, I'd really love to own a 7" or 6" APO if I had an outside observatory...physics would suggest the views should be considerably better than an AP130, although at a significant portability penalty.

 

This bears repeating. From studying the market, it appears that amateurs are primarily pitched 4" vs 5" instruments in refractor-land as the "high end", while the window for, say, reflectors, is much wider--between 10" to 16", with a much fatter long tail toward larger apertures compared to the refractor long tail above 5." Price is obviously the reason for this, as the exponential jump is well documented on CN and elsewhere. However, it also creates the conveniently forced contentment limit at the 4-5" mark for most refractor buffs today. Years ago, the limit was 3-4" because it was simply too expensive to jump to 5"; in the near future, if making 6" glass and mounts becomes as cheap (and profitable) as it is to make 5" OTAs today, the marketing (and goalposts) will likely shift to 6." But as gnowellsct and others elsewhere have noted, the gains throughout the amateur arena are very, very incremental. Somewhere in there there's an essay about Sisyphus...

 

 

And, just personal choice, I do not care to own any more Celestrons either.

I'm confused.  If you've owned so many other apertures, then you would have an idea what larger refractor apertures would bring, more or less.  There is a general view that good planetary observing begins at 5 inches, and it's a view with which I agree, on the whole.  This is in part because you can get to 300x with larger exit pupils.  

 

The larger answer to your question is that the improvements, while they will be there, will be infinitesimal.  Think of it this way. Take a 5 mm pupil and a 102mm as a ratio.  The leap from no scope to a 102mm is vast.  It transforms one's sense of the sky.  So as a ratio what's the next step up of comparable dimensions?  Well to make a 102mm proportionately as small as a 5 mm pupil, the next step up is about 210 cm (83 inches).  

 

Therefore, we can conclude that the gains to be had in moving from 130 to 140 or 160 are very small relative to what the 130 is bringing you in the first place.  And i fact that whole of the amateur class instruments are in the strict sense simply improvements at the margin.    To some extent that's true, which is why so many 60 and 70mm refractor buffs like to show off how much they can see through their preferred instruments.

 

I can see most of what I see in my 4" that I can see in my 5" apo.  But the 5" brings the views to me with a larger exit pupil and makes for more relaxed viewing.  A six inch refractor might further improve on this consideration.   Of course getting to 300x with a larger exit pupil is only one performance criterion; it comes at the expense of wider fields at the low magnification end.

 

If you take a 4 inch and mount it on top of a 14" and inspect Mars or lunar details, etc., it takes quite a bit of time to see the additional details.  However, improvements in color are pretty obvious.

 

GN

 

Indeed. I believe a (sub)conscious realization of this is also why so many people eventually revert to smaller instruments after climbing aperture mountain. I think there are people who have the finances, physical, and (most importantly) mental space to keep 5, 10, or 25 telescopes and binoculars of varying shapes and sizes. However, I think there are also a lot of people who realize the futility of it all (or simply run out of money or physical space) and hop off the aperture bandwagon and are a lot better for it. I haven't been on this path yet in astronomy, but I've seen many on various stages of the path in this and other hobbies (musical instruments, audiophilia, photography, bicycles, motorcycles, cars, birding, etc). In many respects, all of these hobbies are just different manifestations of our relationships with desire (or contentment).


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#119 gnowellsct

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Posted 03 July 2017 - 12:26 AM

Ineed. I believe a (sub)conscious realization of this is also why so many people eventually revert to smaller instruments after climbing aperture mountain. I think there are people who have the finances, physical, and (most importantly) mental space to keep 5, 10, or 25 telescopes and binoculars of varying shapes and sizes. However, I think there are also a lot of people who realize the futility of it all (or simply run out of money or physical space) and hop off the aperture bandwagon and are a lot better for it. I haven't been on this path yet in astronomy, but I've seen many on various stages of the path in this and other hobbies (musical instruments, audiophilia, photography, bicycles, motorcycles, cars, birding, etc). In many respects, all of these hobbies are just different manifestations of our relationships with desire (or contentment).

 

In Japan audiophiles install their own utility poles and transformers to get perfect voltage control or some such thing for their sound systems.   At a cost of about $65k.  

 

That must be quite some sound system.  I don't think the WSJ has open access but here's the link so you can see I'm not making it up.

 

https://www.wsj.com/...od/accounts-wsj


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#120 Fomalhaut

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Posted 03 July 2017 - 08:52 AM

An increase of 1 magnitude corresponds to 2.512 times the previous energy, which again corresponds to the 2.512-fold of objective area, which corresponds the sqrt(2.512) = 1.58times the smaller objective's diameter. 

For only half a magnitude it takes sqrt(1.58) = only 1.26 times the smaller objective-diameter.

 

Using this latter factor of 1.26 ZEISS had apertures of

50mm, 63mm, 80mm, 100mm, (but the next one was rounded to 125mm)

in order to have 0.5mag-steps in between.

 

Notice: If a producer would decide for a certain step of increasement then this should be calculated in % an not in absolute numbers:

Example: The step up from 100mm to 150mm ist the same as from 150mm to 225mm (which are both 50% increases to the previous objective diameter). The relative gain of magnitudes is then the same in both cases.

 

Chris


Edited by Fomalhaut, 03 July 2017 - 08:56 AM.


#121 Jon Isaacs

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Posted 04 July 2017 - 03:45 AM

Indeed. I believe a (sub)conscious realization of this is also why so many people eventually revert to smaller instruments after climbing aperture mountain. I think there are people who have the finances, physical, and (most importantly) mental space to keep 5, 10, or 25 telescopes and binoculars of varying shapes and sizes. However, I think there are also a lot of people who realize the futility of it all (or simply run out of money or physical space) and hop off the aperture bandwagon and are a lot better for it. I haven't been on this path yet in astronomy, but I've seen many on various stages of the path in this and other hobbies (musical instruments, audiophilia, photography, bicycles, motorcycles, cars, birding, etc). In many respects, all of these hobbies are just different manifestations of our relationships with desire (or contentment).

 

 

With many tools, spending more money is an exercise in the laws of diminishing returns.  A $700 road bicycle will be nearly as fast as a $7000 road bike and a fast rider on a $700 bike can drop an average rider on an expensive bike.  

 

But that's not the case with telescopes, at least for the deep sky.  Larger and larger apertures show significantly more and more..

 

In my world, aperture is not a "bandwagon" one hops on, it's just one aspect of set of tools one has for the purpose of observing the night sky. I think of it as a set of tools, much like a set of hammers.  One doesn't want just one hammer, one heeds both small hammers and large hammers.  In a similar way, one wants both small telescopes and large telescopes..

 

For me, the capability versus hassle factor is very important.. My refractors stop at 120 mm because beyond that, for me, a 10 inch Dob has a reduced hassle factor with increased capabilities.

 

A lot depends on your situation, how often one observes, where one observes and how much hassle is involved. I know that a lot of people with large aperture scopes use them infrequently, a few times a year.  That's not me.. I been out 62 nights this year with scopes 12.5 inch or larger, mostly larger and another 25 nights with smaller scopes.

 

Jon


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#122 Redbetter

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Posted 04 July 2017 - 04:41 AM

 I have been out 86 times this year so far according to my log.   37 of those sessions have included my 20" scope.  It is the one I use most frequently (and it is used almost exclusively of the others at dark sites where it goes so much deeper than the others and gets used for far longer sessions than with the others.)  In short, it works for me.

 

It doesn't really matter to me where other observers top out with respect to aperture.  Some get great results with 16", 14" or even 12.5" and I might even be hard pressed to demonstrate I am seeing more with a larger aperture than they are--good for them!   An 18" or 22" are close enough to equivalent to a 20" that it would be splitting hairs to declare one or the other superior relative to the 20".   I am not really jealous of those using 24/25/28/30+ inch scopes because those are not practical for me at the moment.  I recognize the trade-offs for my situation.  I dream though... and eventually...

 

An 8 or 10" scope is quite capable.  I enjoyed my time with an 8" as my only scope and was showing things to more experienced types with larger scopes that they had never targeted before.  A larger scope will show more, but that doesn't make it the best fit for one's circumstances.  What one has the time or resources for is more important than raw aperture.  There is no point in having more aperture than one can frequently use in my opinion.  I lament the years that my big scope was relegated to disuse because of circumstances.

 

As I say to my wife:  the point of a larger scope is to be able to barely detect even fainter objects than I can see now.  That is "aperture fever" for me, being able to push my visual boundary that much deeper.  Nevermind that I can already detect tens of thousands more galaxies than I will probably have the time to observe in my remaining lifetime. 


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#123 gnowellsct

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Posted 04 July 2017 - 10:34 AM

But that's not the case with telescopes, at least for the deep sky. Larger and larger apertures show significantly more and more..

Jon

Last night club members fielded 3.2 inch apo, 5 inch Mak, two c8s, and a c11 for planets and lunar views. On the moon returns in image detail scaled directly with aperture. We also masked the 3.2 down to 41mm about 1.7 inches. The Mak was on a jittery mount and so very often the 3.2 seemed to pull ahead in sharpness. But in any case it was a very straightforward demonstration of aperture effect.

I would say one can readily lose 10 to 40% of effective aperture on a poor mount. It doesn't even take wind. I once had some views through a TEC 140 that made me sad because of focus and tracking jitter (alt az, hand driven).

The night also demonstrated that when the seeing degraded it was not an opportunity for small scopes to pull ahead. The 41mm, 3.2 inch and 5 inch views also deteriorated. GN

Edited by gnowellsct, 04 July 2017 - 10:34 AM.

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#124 Binosaurus

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Posted 04 July 2017 - 10:37 AM



There is no point in having more aperture than one can frequently use in my opinion.  

I like this as another way of expressing the maxim of the best telescope / binoculars being the one used the most. Part of me would love an 8"-10" for more planetary resolution, but I'm not willing to tote anything > 40 pounds, which limits me to either a.) building my own or b.) forking over ~2k, and I'm not ready for that yet.

 

alkaid10.jpg

 

10" f/4 for 24 lbs at 1.8k. I've spent that much on cameras before (twice; one for me and one for my wife, and both were used), but I have a hard time justifying that kind of money these days, despite our being blessed with far more in the kitty. Maybe once the kids are grown and college is done...we'll see. laugh.gif



#125 Jon Isaacs

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Posted 04 July 2017 - 10:58 AM

I like this as another way of expressing the maxim of the best telescope / binoculars being the one used the most. Part of me would love an 8"-10" for more planetary resolution, but I'm not willing to tote anything > 40 pounds, which limits me to either a.) building my own or b.) forking over ~2k, and I'm not ready for that yet.

 

A 10 inch Dob consists of two easily moved, easily assembled pieces that weigh about 30 lbs each.

 

Jon




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