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Should I jump from 10 inches to 15 or 18?

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#51 Gavster

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Posted 30 December 2018 - 04:52 AM

Having just received my first dob, a 16 inch skyvision servocat goto, this is as big as I would like to go.  The jump from my c11 is very noticeable and satisfying. I can also setup the 16 inch by myself and it fits through doorways (just) and can be lifted into my car fine.

Discussions about NV do generate passion on both sides. For me it’s just another (rather nice) tool in the box. NV has definitely reinvigorated my observing from my LP back garden though. Everything is better from dark sites (including NV) but now I enjoy observing at home regularly as well. NV through my 16 inch dob is a lot of fun.

And NV can become a bit intoxicating for me when I get visual views like this..(phone pic through my NV monoculars a couple of months ago)

 

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#52 Shneor

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Posted 30 December 2018 - 05:29 AM

We get questions like this all the time, specifically "I have a 10inch and am looking for the next jump...". Usually this ends with a 16" or 18", and rarely 20". Like Don Pensack says, there's a big difference between 16" and 18" that doesn't seem to fit the profile of a 2" difference. To me it's because the 16" can be loaded without ramps and without a second person. Granted it's at the limit but someone such as the OP it sounds certainly doable*. The 18" is just that much more heavy and the boxes just that much wider where the weight and the girth make the boxes awkward to handle alone. So then you're looking at doing ramps or always have a second person to help load and unload. Further, the stacked height from ground board feet up to the tips of the altitude bearings gets taller with an 18" over the 16" (in general, but there are exceptions) so you end up needing a slightly larger vehicle (think SUV compared to CUV) to haul the 18" than you do the 16".

 

*The caveat here is if the scope does not have a ServoCat system, or if it does the owner is comfortable messing with the altitude drive cable in the dark. If a ServoCat system is installed that essentially locks the mirror box to the rocker box and makes the two boxes one unit, unless you want to unwrap (and then re-wrap) the altitude drive cable each time the scope is put into or taken out of your vehicle. I've found most people don't want to mess with doing that, but I've spoken to others who are completely fine doing it. If you don't want to wrap/unwrap the cable then the combined weight of the 16" mirror box and rocker box is beyond what most people are comfortable lifting, let alone carrying any appreciable distance. 

 

There are some variables here to consider and options of scope design to figure out. 

 

Good luck with your research and future purchase.  Take care,

I am just amazed at the presumed difficulty of dealing with an 18". My 22" is a one-person setup, no ramps needed; the heaviest piece is about 60 pounds, and handleable for me, and I'm in my 70's. My Hubble Optics 18" , which I plan to use in my 80's is also an easy one-person setup

and the heaviest part is only about 35 pounds. Either easily fit, with an equatorial platform and tons of accessories, camping gear, 12 gallons of water, etc. in my little Honda Fit. It's all a matter of design and materials. Aluminum instead of wood, for example. "uff said.


Edited by Shneor, 30 December 2018 - 05:30 AM.

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#53 ICit2

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Posted 30 December 2018 - 12:32 PM

It seems odd that someone who advocates for night vision devices would mention "cannot afford" in the same paragraph.

For the price of one night vision device and a basic 12" scope, you could have a fairly high end 15-16" scope.

I've read a lot of your post on CN which reflect your extensive experience and knowledge in these matters.  So, yes, you could get that high end 16".  But you still wouldn't have the ability to use 12 or 7nm narrowband filters.  And the 12", or his 10", would show more with NV then the premium 16" without it, is what I'm getting at.  But hey, these things are always dependent on ones particular situation and likes.  There is no one size fits all.  And maybe trying to figure that out is just part of the fun.


Edited by ICit2, 30 December 2018 - 12:33 PM.


#54 Starman1

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Posted 30 December 2018 - 01:12 PM

And you have to admit the pic in post 51 is impressive, given that is close to the naked eye scale.


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#55 Redbetter

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Posted 30 December 2018 - 02:17 PM

And you have to admit the pic in post 51 is impressive, given that is close to the naked eye scale.

Yes.  I was able to just visually detect the wide roundish glow of nebula to the extent in the image around Orion's head, lambda Orionis, with the ST80 w/2" focuser using 41 Pan and 2" H-beta filter.  It is a rather subtle thing, but there. 

 

Barnard's loop is somewhat less difficult to trace with H-beta when conditions are good.  I have traced that all the way between the feet using apertures from 60mm to 20"...takes a lot of slow panning with the 20".  Two nights ago I was unable to observe at my usual spot (stupid wall shutdown fallout) but slipped in with 2.3x Galilean type binocs for a few minutes.  I did not put in a filter but could still visually detect the brighter arc of the loop.



#56 Starman1

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Posted 30 December 2018 - 08:00 PM

I have seen Barnard's Loop with the naked eye and an H-ß filter held up to the eye,

and pretty much the entire length shown in your image.

It is, of course, nowhere near as bright as shown in the image.


Edited by Starman1, 30 December 2018 - 08:01 PM.

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#57 Asbytec

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Posted 30 December 2018 - 11:31 PM

And you have to admit the pic in post 51 is impressive, given that is close to the naked eye scale.

How would you like to have skies and eyes that allow such a striking view. My gosh...imagine waking one early morning and seeing that rise over your house. 

 

But, with telescopes, the Flame and Orion nebulae are much bigger and more resolved. So...



#58 Shneor

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Posted 31 December 2018 - 12:40 AM

I have seen Barnard's Loop with the naked eye and an H-ß filter held up to the eye,

and pretty much the entire length shown in your image.

It is, of course, nowhere near as bright as shown in the image.

I missed that particular night 15-20 years ago, but my observing buddies told me that Barnards Loop in its entirety was naked eye that night at Blue Canyon. Sadly, those occasional spectacular nights there seem to be a thing of the past.



#59 TareqPhoto

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Posted 31 December 2018 - 06:33 AM

Is this thread about jumping to larger scope or about NV performance?


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#60 25585

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Posted 31 December 2018 - 10:48 AM

Having just received my first dob, a 16 inch skyvision servocat goto, this is as big as I would like to go.  The jump from my c11 is very noticeable and satisfying. I can also setup the 16 inch by myself and it fits through doorways (just) and can be lifted into my car fine.

Discussions about NV do generate passion on both sides. For me it’s just another (rather nice) tool in the box. NV has definitely reinvigorated my observing from my LP back garden though. Everything is better from dark sites (including NV) but now I enjoy observing at home regularly as well. NV through my 16 inch dob is a lot of fun.

And NV can become a bit intoxicating for me when I get visual views like this..(phone pic through my NV monoculars a couple of months ago)

Definitely prefer white phosphor! What eyepieces are best for NV as I presume long eye relief/projection is required? Again presuming, but large exit pupil so shorter FL choice of scope is better? 

 

I am aware this crosses over to other forums, but from a suitable backyard Newt POV I ask. Also would a truss tube be less effective with NV?  



#61 Gavster

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Posted 31 December 2018 - 05:37 PM

Definitely prefer white phosphor! What eyepieces are best for NV as I presume long eye relief/projection is required? Again presuming, but large exit pupil so shorter FL choice of scope is better? 

 

I am aware this crosses over to other forums, but from a suitable backyard Newt POV I ask. Also would a truss tube be less effective with NV?  

I think to avoid sidetracking this thread further, it would be better if you asked any NV questions you have on the EAA forum where I and others would be happy to provide detailed answers.


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#62 InkDark

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Posted 01 January 2019 - 01:32 PM

I'm in the same boat. I have a 10 inch and thinking of going to a 15 inch. I must admit that the picture in post 51 makes me suddenly hesitate. 

 

I like the purity of the views, but better see something than nothing because of light pollution. 


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#63 25585

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Posted 02 January 2019 - 11:35 AM

Upsizing from 10 inches is a lot harder to decide on than going from an 8 inch. I did the latter to my 12 inch F5, which is where I have stayed, now using 10 inch Dobs mainly. 

 

A 14 inch lightweight solid tube OTA is attractive on paper, but not realistic. 



#64 brentknight

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Posted 02 January 2019 - 05:04 PM

Just curious 25585, why you use the 10" scopes over the 12".  I just jumped from a 10" f/6 to the 14" -- other factors such as Go2 and heavier base structure make this scope MUCH more to handle, but not too much more.  I'm seriously considering selling the 10" as I'm not sure how much use it will get now...

 

But to speak to the OP, I believe this jump in size is more than worth it.  I considered 15" to 18" but cost and size and my age always pointed me back to the 14".



#65 TareqPhoto

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Posted 02 January 2019 - 05:53 PM

Just curious 25585, why you use the 10" scopes over the 12".  I just jumped from a 10" f/6 to the 14" -- other factors such as Go2 and heavier base structure make this scope MUCH more to handle, but not too much more.  I'm seriously considering selling the 10" as I'm not sure how much use it will get now...

 

But to speak to the OP, I believe this jump in size is more than worth it.  I considered 15" to 18" but cost and size and my age always pointed me back to the 14".

Good question, some go from larger to smaller, and other the opposite, can't put all people in same scale and reasons, i wanted to go larger and larger for planetary anyway, and dobsonian is likely cheaper so if i have good budget i can also buy a mount for it, while if i put this budget for SCT or Rc that large then i will end up with only the scope but no mount to handle it, it will be definitely a waste then, and i have to wait so long, $7000-8000 better been spent on 2 items than one.



#66 25585

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Posted 04 January 2019 - 06:12 PM

Just curious 25585, why you use the 10" scopes over the 12".  I just jumped from a 10" f/6 to the 14" -- other factors such as Go2 and heavier base structure make this scope MUCH more to handle, but not too much more.  I'm seriously considering selling the 10" as I'm not sure how much use it will get now...

 

But to speak to the OP, I believe this jump in size is more than worth it.  I considered 15" to 18" but cost and size and my age always pointed me back to the 14".

Quite a difference in weight and size between a 10 & 12 F5. I bought my 10 as a first modern Dob, having had old heavy 1980s models before. Then I got nostalgic for the 12 I used to have, so bought an OTA which can use the original mount.

 

That 12 F5 was harder on my back carrying, but taller so better for standing. Eventually I got tge F6 10 inch, same height as my 12 F5, but easier to take around, and also collimate. However the 10 F5 is short enough to be car tranportable, so it has its own niche. All are solid tube.

 

There is a difference comparing both aperture sizes, though only 2 inches different. Most notable with nebulas and galaxies, the former using OIII filters especially benefits from using those extra 2 inches. With globular clusters I am uncertain, my F6 gives darker sky and better contrast, but the light splash in my 12 F5 is brighter. For star colours in globs not much difference, in open clusters depends on the colours. 

 

Moon, planets and doubles show better with my 10 F6.

 

To the OP, buy or try an 18 first. You will find out if its too big and get an idea of whether its size suits. If you feel happier downsizing later, at least it will be with experience. I tried a 14 once, decided 12 OK, but now a quality 10 inch does fine and gets used most. 


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#67 Jon Isaacs

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Posted 04 January 2019 - 06:35 PM

With globular clusters I am uncertain, my F6 gives darker sky and better contrast, but the light splash in my 12 F5 is brighter. For star colours in globs not much difference, in open clusters depends on the colours.

 

In a decent scope, sky darkness is a function of exit pupil so that at the same exit pupil (20% more magnification in the 12 inch) the sky will be equally bright in both scopes but the stars will be brighter in the larger scope since their point sources..

 

Jon


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#68 donald41

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Posted 17 January 2019 - 08:49 AM

you will have to consider weight and size before shelling out them bucks. i had a 10" then i got the fever for more ap, so i bought a 12" could not see much difference in the seeing and the weight and size was a lot more then the 10" so i sold it and went back to a 10" and happy i did. i got to a point were i didnt wont to take the 12" out so it just set in my garage. the best scope is the one that is easy to take out and set up and get the most in what you can see under your skies. i have a 114 orion reflector and love the wide field of view. 


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#69 ICit2

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Posted 27 May 2019 - 01:32 PM

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.

Proper balance is critical when it comes to ultra lights dobs.  I just got a Hubble Optics UL16 and it's smooth as glass.  The 18" classic is a different animal structurally and easier to balance than a UL20.   My guess is your friend doesn't have his UL20 balance properly.

 

Here a review on the Hubble Optics UL16 that covers balance. (end of video)

https://www.youtube....h?v=4FuGniNZlg4



#70 Starman1

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Posted 27 May 2019 - 03:33 PM

An update:

1 magnitude jumps:

6">>10">>16">>25">>40"

8">>12.5">>20">>32">>50"

See any popular sizes there?

For 0.5 magnitude jumps, combine the rows.

But I recommend 1 magnitude jumps whenever possible.

It does make me wonder why there are 11", 14.5", 15", 17.5", 18", 22", 24" and 28" sizes.

My guess is that each person has a maximum tolerable size and that sometimes the 1 magnitude jumps are too much to handle.


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#71 TareqPhoto

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Posted 27 May 2019 - 06:07 PM

An update:

1 magnitude jumps:

6">>10">>16">>25">>40"

8">>12.5">>20">>32">>50"

See any popular sizes there?

For 0.5 magnitude jumps, combine the rows.

But I recommend 1 magnitude jumps whenever possible.

It does make me wonder why there are 11", 14.5", 15", 17.5", 18", 22", 24" and 28" sizes.

My guess is that each person has a maximum tolerable size and that sometimes the 1 magnitude jumps are too much to handle.

So i have 8" scope already, then i should jump to 12.5", but i hate to stay lower than 14" anyway, so the next ideal jump for me should be 20".



#72 clusterbuster

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Posted 27 May 2019 - 06:13 PM

In the words of Van Halen:

 MIGHT AS WELL JUMP !!!

 Mark

 

Get that Big Aperture

Globs and Galaxies and everything else will DAZZLE your eye !


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#73 Starman1

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Posted 27 May 2019 - 07:09 PM

So i have 8" scope already, then i should jump to 12.5", but i hate to stay lower than 14" anyway, so the next ideal jump for me should be 20".

Well, 1 magnitude makes a profound difference.  Any size larger than that will be >1 magnitude, so even more impressive.

8 to 16" is about a magnitude and a half, and a 16" can be moderately portable.



#74 Richard Whalen

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Posted 27 May 2019 - 07:28 PM

15" gets my vote.



#75 niallk

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Posted 28 May 2019 - 04:07 PM

I went from a 10" Skywatcher to a 15" Obsession and have been very happy with the noticeable benefits on DSOs such as planetary nebs, reflection/emission nebs, galaxies and in particular globs are quite dramatically enhanced. I saw strong green in Orion in my 10"; I've seen tinges of pink in my 15". I also find the extra aperture great for using an O-III and pushing power on PNs.

The mirror has delivered best views ever of planets- and really importantly, the structure moves so nicely, precisely and without backlash or vibration, that it makes high power observing a pleasure. Ive seen hints of detail within the GRS, and Io as a little '3d' ball.


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