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Should I jump from 10 inches to 15 or 18?

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#1 JaredLeeNewton

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Posted 26 December 2018 - 12:09 PM

Ive been an avid observational astronomer for a while now. Wanting to expand my viewing experience. I have mag 5 to 6 skies where I live in Kentucky, and can drive to fairly dark sites. Im going to keep my 10 inch as I plan to give it to my daughter when she gets older. Im wanting to know, from people with experience in this switch, pros and cons of 15 inches vs. 18 inches. Also is 15 enough of a jump for a wow factor, or should I just consider the 18? Let it begin lol



#2 ShaulaB

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Posted 26 December 2018 - 12:17 PM

15 or 16 inches in aperture will definitely give you a WOW factor. You will notice this with the increased detail you can see in planets (Jupiter, Mars, Saturn). Of course you will notice how much brighter, and even hints of color, you will see in DSO's. If you can get a premium mirror, so much the better. Know in advance you will need to collimate the scope before every observing session, and on some viewing runs, you might need to collimate every few hours.

 

18 inches? How much can you bench press?


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#3 ICit2

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Posted 26 December 2018 - 12:20 PM

Keep your 10" and get a PVS14 Night Vision monocular.  It will beat the 18 and you'll have a much more portable set up with plenty of wow. 

Here's a "night vision workshop" video I did on the subject:  https://www.youtube....h?v=6usKtqpVMi8


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#4 vdog

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Posted 26 December 2018 - 12:37 PM

Go as big as you can afford and are willing / able to lug around.  Life is short; be happy.


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#5 cliff mygatt

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Posted 26 December 2018 - 01:02 PM

Doing the math, a 15 inch scope will double your light gathering area and an 18 inch scope will triple your light gathering area.  Both will give you a Wow factor change and if you are willing to handle and transport the 18 inch scope I would go for it.  I went from an 8 inch SCT to a 12 inch dob with a premium mirror and am loving the extra light?  Good Luck!



#6 GilATM

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Posted 26 December 2018 - 01:18 PM

IMHO , you will see about the same thing, most of the time.   The biggest difference in the hobby is between the naked eye and any telescope at all.   So the most useful advice is the age old "the best sized telescope is the one you use the most."    There is, however, a distinct difference in my enjoyment of viewing between fair optics and good optics.   So another option is to upgrade the mirrors of your 10" (both primary and secondary) and just keep going!

 

Luckily, none of these options create a future disaster - so if you stay in the hobby you are likely to bounce around various options until you find what fits you best.    I have settled on 12.5" as my top end for scopes, but that is just me.  

 

Gil


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#7 TOMDEY

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Posted 26 December 2018 - 01:40 PM

Hard to find people who regret going bigger... unless/until the geriatric stage of life takes over. I am immensely enjoying my 36-inch scope, but circumvented the logistics problems... by putting it in a dome, on a rural hill, behind my house... and retiring, so I don't have to get up in the morning, to go to work. I'd recommend that approach. Ummm... the getting older part, haven't quite mastered that annoyance, yet.    Tom, optimistic Tom


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#8 Astro-Master

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Posted 26 December 2018 - 02:22 PM

I went from a 10" to a used Obsession 18" and it has been the best scope ever.  It's a large scope but easy to handle.  My friend has a 15" Obsession and it is very nice, but the 18 is awesome.  If you like seeing detail in galaxies, get a 18 or 20".

 

I'm 72 years old and its still easy to ramp it into the back of my pickup.  My advise is to save some money and buy a good used premium Dob.   I paid $3,000 10yrs. ago for my 18, and its worth more today, try doing that with a Dob made in China.

 

You will never be sorry buying quality.  You'll thank yourself every  time you use it.  Buy a used Dob on CN from someone with a good rating for peace of mind.  Be patient there are a lot of us older astronomers that are downsizings, but I'm not one of them.  Good luck in your search.


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#9 dgoldb

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Posted 26 December 2018 - 02:25 PM

As big as you can transport and view comfortably with.  (If you dislike ladders, 16" is as big as you can go for f/4.5 scopes. Depending on your height, 18" f/4 might work very well.)



#10 stoest

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Posted 26 December 2018 - 02:47 PM

I moved from a 9.25 SCT to an 18" dob and the difference is amazing.  I think if you're going big dob then you have to work out how much you're willing to transport and setup each time you use it. I live in a very light polluted suburb with my dark sky site about two hours away and if the moon and weather are cooperating for a weekend then I'm making plans to observe at the dark site.  I've had the 18" for almost a year now and I'm really just scratching the surface of what I can do with it but I'm loving every minute of it. 

 

I can view at the zenith with my F4 mirror, F4.6 scope with the Paracor and I'm average height. 



#11 Kunama

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Posted 26 December 2018 - 02:55 PM

I went from a 10" to a used Obsession 18" and it has been the best scope ever.  It's a large scope but easy to handle.  My friend has a 15" Obsession and it is very nice, but the 18 is awesome.  If you like seeing detail in galaxies, get a 18 or 20".

 

I'm 72 years old and its still easy to ramp it into the back of my pickup.  My advise is to save some money and buy a good used premium Dob.   I paid $3,000 10yrs. ago for my 18, and its worth more today, try doing that with a Dob made in China.

 

You will never be sorry buying quality.  You'll thank yourself every  time you use it.  Buy a used Dob on CN from someone with a good rating for peace of mind.  Be patient there are a lot of us older astronomers that are downsizings, but I'm not one of them.  Good luck in your search.

Agreed 100%

A secondhand premium 18" would give the WOW factor you're seeking over a 10".  18"-20" will show subtle colours in some nebulae, it will show star colours beautifully and will be superb on planets.

It will bring a lifetime of DSOs to you.  I am not into EAA or NV gear, preferring to see directly the things my scope can show.  When I run out of targets within the 18s reach I will build a bigger scope.....


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#12 stargazer193857

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Posted 26 December 2018 - 03:46 PM

I bet it is true that if you don't have injuries, 18" is a great size. 18" f4 for no ladder. I've seen M51 in a 20" and a 12" at the site an hour apart. Much more detail and color in the 20".
If my joints we're not bad, I'd gladly stand on a step ladder and use the 18".
Good call on keeping the 10".


I've seen a 10" schmidt newt put a very obvious grey spiral for M51 with a 13mm Ethos. But the 20" showed it bigger, and blue arms with purple knots.
I got out of there when the 20" owner said he was going to take it down soon. I was afraid he would ask me to lift something. He had said he could easily do it himself, so I don't feel too guilty.

Edited by stargazer193857, 26 December 2018 - 03:57 PM.

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#13 Redbetter

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Posted 26 December 2018 - 04:16 PM

Going from 10" to 15" is a substantial jump, about 0.9 magnitude.  Jumps that big tend to have a "wow factor."  15 to 18" is an additional 0.4 magnitude, but 1.3 magnitude over the 10".    Since you are keeping the 10" the question is more of where the extra aperture becomes a hassle/problem to transport and use.  That depends on you and your situation. 

 

Consider how you would use the new scope, how you will transport it/how it will fit when loaded, what additional stuff you will need with it (e.g. ladders or observing chairs), who will be along with you for the trip, and the associated stuff for camping, etc.  Plan for a scope that you can reliably load/unload without any help.  This should help you define the maximum practical size for your needs.  And consider whether you will still be able to handle the same scope in 5 to 10 years.   

 

There is some advantage to maximizing the useful aperture while one is young--better eyes and better fitness for using the scope, rather than realizing one can no longer go bigger a decade or two later.  However, if you undershoot a little on aperture, it is no great loss either.  You might find some things are incrementally out of reach, but should have a more manageable scope as compensation.  It will probably not be enough of a difference that you will actually regret undershooting and end up switching to the next size up.  On the other hand, if you overshoot by an increment it could very well limit the usefulness of the scope to you in a significant way. 


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#14 Astro-Master

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Posted 26 December 2018 - 04:52 PM

Jared, 

 

If  the picture on your post is of you, it looks like you are young and fit.  You should have no trouble handling an 18".  I would recommend the classic design over the lightweight.  The lightweight takes longer to set up and is not as stable.  The classic design also has better light baffling, and room for finder scope and accessories..

 

IMO, I think an 18" F4 to F4.5 hits a sweet spot.  Under dark skies there is a noticeable increase in performance over a 15", without a big increase in weight.  The difference between a 18' and a 20" is not as much as 15 to 18, but the weight, the height, and the cooling time for a 20" mirror is more.



#15 kfiscus

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Posted 26 December 2018 - 07:59 PM

I moved up from a 10" to a 12" and then stopped at a 16" f/4.5 truss.  The views were worth the $$$ and work to upgrade the 16" scope to my liking.  I'm short (5'8") and have to use the 2nd step of my stepladder for views near the zenith.  I use the 12" ten times more often than the 16" because it is so much easier to move...


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#16 stargazer193857

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Posted 26 December 2018 - 09:30 PM

If you are driving all the way to a dark sky site, it is not much extra effort to bring a big one, and the views could make it worth the drive. But for the old or weak, loading the scope into the car may be the bigger issue. At home though, you have the 10" for the lazy days. If you did not have the 10, I would definitely limit it to 15".

The main question is whether you can afford an 18" f4 or mind using a small step ladder for an f4.5. A 15" f4.5 is inexpensive and feet on the ground.

Another concern is with bigger aperture, the scope focus becomes more seeing dependent.

#17 Shneor

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Posted 27 December 2018 - 02:23 AM

Jamie, go for the 18". I'll even recmmend one: the Hubble Optics 18". I bought one used for a time that may come in which I won't be able to move my 22' around any longer. The mirrors are excellent, setup and takedown are quick (10-12 minutes) and the folding bearings make it easy to switch from light to heavy eyepieces and back without any movement (although more or less permanent weights will help). This baby keeps collimation over time and travel. The heaviest part is only about 35 pounds, and the primary adjusts to ambient temperature rapidly. There are optional items available. Oh, and you will be able to see pretty deep - on a excellent dark night in February, for example, you may be able to see the Double Quasar in Ursa Major, probably pulsating in and out of view. Go for it!


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#18 Astro-Master

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Posted 27 December 2018 - 02:54 AM

I looked through the Hubble Optics 20" under a dark sky next to my Obsession 18" classic.  The mirror did cool down very quickly, and gave very nice views. but the movement in azimuth was way to loose, and the altitude was so stiff, it was a pain to use.

When the owner of the 20" looked through my scope he was amazed how smooth the scope moved.

 

My advice, try before you buy.  Go to some big star parties, look through as many scopes as you can.  One important point, buy from a dealer in the US.  Its easier then dealing with someone overseas.



#19 Asbytec

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Posted 27 December 2018 - 03:35 AM

Get the biggest scope you can manage easily enough, without a ladder apparently.
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#20 niallk

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Posted 27 December 2018 - 04:23 AM

I went from a 250px to an Obsession 15" Classic, and the aperture step up was definitely worth it - and I muttered a wow on M81/82 - the first targets on the night of my 1st light session :) Globs are amazing, and PN too. The scope is a joy to use due to the beautiful movements, and I've hand tracked Jupiter at 560x on a rare night of great seeing.

Would I like an 18"? In theory, hell yeah. But the truth is that the 15" mirror box is pretty heavy, and I can't just roll out into my car. I suspect the 18" might get less use for my circumstances. On the other hand if you can afford it, and can roll from storage to observing/your car, go for it!

#21 WyattDavis

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Posted 27 December 2018 - 05:01 AM

 I would recommend the classic design over the lightweight.  The lightweight takes longer to set up and is not as stable.  The classic design also has better light baffling, and room for finder scope and accessories..

Regardless of where you end up on aperture size, this is great advice. I am moving from a lightweight structure to a "classic" design for these reasons (and, I'm holding at 10").


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#22 stargazer193857

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Posted 27 December 2018 - 11:29 AM

I saw M82/81 in an 18" and was not impressed. Then my friend had the owner take it to high power. Then he was impressed at the structure he saw. I did not look, so I'm still not jumping on 18". Also, I'd have to first see what a smaller scope can do at high power.

I think the main difference is the brighter big scope lets you look right at it.

Edited by stargazer193857, 27 December 2018 - 11:30 AM.


#23 MitchAlsup

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Posted 27 December 2018 - 11:42 AM

20 years ago I jumped from a 11" SCT to a 20" DOB.

 

However, you should consider how you are going to transport "the thing". You will find a 15" a lot easier and less bulky and clumsy to transport than an 18" or larger scope. 15" is about the minimum aperture gain (50% diameter growth) for getting the next level of WoW out of your viewing experience.


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#24 Eddgie

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Posted 27 December 2018 - 12:47 PM

Keep your 10" and get a PVS14 Night Vision monocular.  It will beat the 18 and you'll have a much more portable set up with plenty of wow. 

Here's a "night vision workshop" video I did on the subject:  https://www.youtube....h?v=6usKtqpVMi8

Yes, this is exactly what I would recommend too.

 

 

Current scope will pick up a couple of magnitudes, equalling maybe a 20" or larger aperture, but in the same small package.

 

Plus (and this is a big big big plus), because you can use long pass filters to defeat a great deal of light pollution, the range of targets available expands greatly.

 

Galaxies that you struggle to see today will usually be better. 

 

Nebula will be titanic. 

 

Not cheap, but cheaper than a 20" dob, and a lot easier to use.  

 

This is not a many hour long exposure.  It was taken with a cheap Andriod Cell Phone simply held up to the eyepiece. The phone made the exposure (about 10 seconds).   There is no post processing or anything.

 

This was taken from a red zone sky using a 12" f/4.9 dob. 

 

And this picture fall far short of showing the richness of the structure at the core of the nebula.   In that region, using the eye, it is like rich, burled walnut. 

 

This is green but new devices can also be purchased that have white displays (I have one, but in many ways I prefer the green).

 

Again, this is a cell phone picture simply held up to the eyepiece of the device (device was used at prime focus):

 

Orion.jpg

 

This is the type of device used for this picture.  It plugs into the focuser just like any other eyepiece:

 

Micro in hand.jpg


Edited by Eddgie, 27 December 2018 - 12:54 PM.

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#25 Asbytec

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Posted 27 December 2018 - 02:14 PM

NV is tempting, and folks are thoroughly enjoying the medium. I get the urge periodically and go hinting for equipment. But I feel it doesn't provide the full resolution of a 20". Maybe not even a 10". Correct me if I'm wrong, of course.

What I mean is, I was observing the bright center of the Orion nebula at 300x and taking in the beautiful sight of soft light and dark regions. If NV can do that and show more, then it can enhance the visual experience. If not, then it lacks in some way important (to me). The eye is pretty good at some things, NV at others. I'm not sure how NV compares to visual even if the Horsehead is super easy.

Not an NV thread. It's about ladders and tall, apparently large aperture scopes, and that conversation led to smaller scopes and seeing more. I get that. My post is not a bash NV write up, rather intended to ask an honest question about this being the way to go to get off a ladder.

 

Edit: Whoa, this is nice. New generation stuff, I imagine, white phosphor.  These are static images, live is more dynamic. The Swan looks like I remember it under clear dark skies in my 18" Dob. 

http://www.loptics.c...ightvision.html


Edited by Asbytec, 27 December 2018 - 03:28 PM.

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