Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

A 10 inch dob- good enough?

dob reflector
  • Please log in to reply
78 replies to this topic

#26 Cajundaddy

Cajundaddy

    Surveyor 1

  • *****
  • Posts: 1525
  • Joined: 27 Dec 2016
  • Loc: Cucamonga CA

Posted 28 October 2018 - 10:37 AM

You already have experience and a nice selection of eyepieces so it's time to add aperture and get the Dob.

 

A 10" will provide 4x the light gathering of your current scope and under dark skies it will reveal a LOT more detail on faint fuzzies like galaxies and nebula.  This is where a 10" really shines.

 

Planetary views require 3 things in this order:

 

1. Steady skies and good seeing

2. A well collimated scope with quality optics

3. Thermal equilibrium to eliminate tube currents that distort your views.

 

A good 5" reflector will offer pretty good planetary views if all of the above are in place.  A 10" can potentially deliver a lot more detail but is also a lot more sensitive to the points above.  I own both a 90mm Mak and 8" SCT.  Both deliver good planetary views but surprisingly, the C90 can be as good or better on planets when the skies are less than ideal.  Under dead calm skies with 9/10 seeing conditions, the C8 wins hands down.

 

Get the Dob and enjoy!


  • Jon Isaacs, Jeff B and Jimmy462 like this

#27 Orion1802

Orion1802

    Sputnik

  • -----
  • topic starter
  • Posts: 45
  • Joined: 10 Sep 2018

Posted 28 October 2018 - 10:40 AM

Hi
So by thermal equilibrium you mean no temperature difference between the primary and atmosphere?
It has a built in fan for that.
Thanks
  • Cajundaddy likes this

#28 JKAstro

JKAstro

    Mariner 2

  • *****
  • Posts: 230
  • Joined: 11 Aug 2006

Posted 28 October 2018 - 10:45 AM

Orion1802

Wait and get the 10" DOB. You'll be so happy with it.

Agree 100%


  • Jon Isaacs and MrJim like this

#29 Jimmy462

Jimmy462

    Mariner 2

  • *****
  • Posts: 258
  • Joined: 22 Apr 2014
  • Loc: Putnam County, NY

Posted 28 October 2018 - 10:46 AM

Jimmy G,

I wanted to know once that as mvas above said "an increase of 1 magnitude, from 13 to 14.5" if the limiting magnitude increases only by 1 then what other significant changes do DSOs show?

Thanks

Well, there's a bit more to seeing and seeing details in DSO objects than just the "ideal conditions" aperture/magnitude gains cited by mvas above. Those numbers cited refer to the limiting stellar magnitude for each aperture, figuring out the visibility (limiting magnitude) of non-stellar DSO objects is a bit more convoluted...

 

The number one factor will be the amount of light pollution that you will be contending with at your observing location. Case in point, here's a link to a light pollution map for my club's public observing site in NY...

 

ClearDarkSky Light Pollution Map: Ward Pound Ridge Reservation, Cross River, NY

http://www.cleardark...=great red spot

 

...the cross hairs indicate that we observe from a, um, "moderately" light polluted and relatively, er, "not-so-good" location in an "Orange Zone". Comparing the performance of your current 130EQ vs your desired 10-inch GSO Dob at that site the larger scope will, of course, reveal more DSO's and more detail in those objects than the smaller scope but neither scope will be performing to their potentials based on the light pollution washing out vital contrast details. The limiting-magnitude for DSOs will improve in darker green, blue, and black locations and lessen the closer one observes to red, grey and white zones.

 

You can discover the light pollution from your location either here...

 

Clear Sky Chart Homepage:

http://cleardarksky.com/csk/index.html

 

...where you can learn about other contributory what other factors like atmospheric transparency, seeing, darkness, wind, humidity and temperature will be like at your location, as well. Or you can discover your light pollution zone here...

 

Light Pollution Atlas 2006:

http://djlorenz.gith...erlay/dark.html

 

...so there are a lot of factors that will go into what one can and cannot see in DSO with their particular telescope on any given night. But, for sure, optical quality between the two being equal, the larger scope will "go deeper" for DSOs and provide greater resolution for the planets...conditions permitting!

 

:)

JG


  • Asbytec likes this

#30 Waddensky

Waddensky

    Vostok 1

  • -----
  • Vendors
  • Posts: 139
  • Joined: 18 Sep 2017
  • Loc: The Netherlands

Posted 28 October 2018 - 10:54 AM

A 5 inch reflector now. My main problem is planetary viewing. Will it give me decent views? Any photo for reference please?
Thanks

You'd better try to find some sketches made with a 10 inch. These give a much better idea of what you can expect than a picture made through the scope.

You can magnify quite a bit using a 10 inch scope, but to repeat others: seeing and optical quality may limit the range of magnifications that are available.

Edited by Waddensky, 28 October 2018 - 10:55 AM.

  • Jimmy462 likes this

#31 Orion1802

Orion1802

    Sputnik

  • -----
  • topic starter
  • Posts: 45
  • Joined: 10 Sep 2018

Posted 28 October 2018 - 10:58 AM

Thanks everyone, 10 inch is final
Clear skies
  • MrJim, gene 4181 and Jimmy462 like this

#32 aatt

aatt

    Surveyor 1

  • ***--
  • Posts: 1756
  • Joined: 26 Jul 2012
  • Loc: CT

Posted 28 October 2018 - 11:33 AM

Congrats! A good decision and it will serveyou well.It is a very capable aperture and portable as well.



#33 Asbytec

Asbytec

    Guy in a furry hat

  • *****
  • Posts: 13635
  • Joined: 08 Aug 2007
  • Loc: Pampanga, PI

Posted 28 October 2018 - 12:06 PM

Orion1802
Wait and get the 10" DOB. You'll be so happy with it.

I agree. A 10 is getting well into serious scope territory. Might be best enjoyed with a complimentary set of eyepeices. So, if given a choice, Id take the 10" and upgrade eyepeices later.

But, if the OP father is willing to buy a set of eyepeices, if as Jimmy said above, he could "parlay his resources" into getting the scope on his own sooner than a year and a half. He obviously has aperture fever that must be addressed so he can crank it to 400x. :)

Just another option to consider with his dad as Christmas approaches. With both working the purchase, this does not have to be an either or proposal. Again paraphrasing Jimmy, find a path to fruition.

Get both, get a good scope and a set of (not terribly expensive) semi wide eyepieces worthy of a serious instrument. A good set can be had for about the same price.

Edited by Asbytec, 28 October 2018 - 12:11 PM.

  • Jimmy462 likes this

#34 MrJim

MrJim

    Mariner 2

  • -----
  • Posts: 217
  • Joined: 24 Aug 2009
  • Loc: Chicago, IL

Posted 28 October 2018 - 05:02 PM

When that long-anticipated time to get your 10" comes around, it will be VERY important to do your due diligence in selecting which 10" to purchase. There is a wide range of prices and quality available and you might want to be sure your father is aware what a good quality 10" will cost.

 

You don't want to wait two years and then find out that your father has "sticker shock" when he sees the price of a nice 10". Now you get the fun of deciding which 10" is the scope of your dreams - enjoy!



#35 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 30 October 2018 - 08:30 AM

This sounds negotiable to me. Try for a shorter time period for the 10" dob IF you save up and pay for a portion of it.
If your father gave you such a choice I bet he'd be impressed enough by the willingness to contribute to it to agree.

#36 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 30 October 2018 - 08:31 AM

The above advice is from a very appreciative owner of a 10" dob.

#37 stargazer193857

stargazer193857

    Fly Me to the Moon

  • *****
  • Posts: 6322
  • Joined: 01 Dec 2013
  • Loc: Southern Idaho

Posted 30 October 2018 - 09:02 AM

Get the 5" now. 2 years is a long time. Ask him to get a used 5" inch on astromart and used eyepieces on cloudy nights. Then sell both for you money back in 2 years and get the 10".

#38 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 30 October 2018 - 10:53 AM

Get the 5" now. 2 years is a long time.

In the OP we were told he already has a 5" scope. The choice is between accessories for that soon, or for a 10" dob in two years.

#39 Orion1802

Orion1802

    Sputnik

  • -----
  • topic starter
  • Posts: 45
  • Joined: 10 Sep 2018

Posted 30 October 2018 - 10:59 AM

In the OP we were told he already has a 5" scope. The choice is between accessories for that soon, or for a 10" dob in two years.

Yes, I already own a 5 inch scope

#40 25585

25585

    Apollo

  • *****
  • Posts: 1281
  • Joined: 29 Aug 2017

Posted 30 October 2018 - 12:53 PM

10 inch Dobs will be a lot heavier than a 5 inch. Negotiate for an 8 sooner, + some eyepieces. An 8 inch F6 would be fine for Moon and planets. Then you can consider a 12" as next up wink.gif


Edited by 25585, 30 October 2018 - 12:55 PM.


#41 Jeff B

Jeff B

    Fly Me to the Moon

  • *****
  • Posts: 5216
  • Joined: 30 Dec 2006

Posted 30 October 2018 - 01:04 PM

10 inch Dobs will be a lot heavier than a 5 inch. Negociate for an 8 sooner, + some eyepieces. An 8 inch F6 would be fine for Moon and planets. Then you can save for a 12" wink.gif

Actually, I tend to agree, except I'd go for an 8" F7 as it's much lighter and easier to set up and collimate than a 10" F6.  A quality 8" aperture can provide devastatingly good planetary views.  The trouble is that F7 focal ratio is not very common and would more than likely be custom.

 

But no matter what you decide on, there is some mighty sage advice here concerning getting a planetary scope that has:

 

1. Excellent optics

2. Excellent build quality

3. Easy to collimate

4. Will keep its collimations of the primary, secondary and focuser during the night and no matter where in the sky you point it.

5. Excellent, active cooling, including a boundary layer fan for the primary, especially if you live where you actually experience winter.  

 

Now since you seem planet-centric with this next scope, let's talk about your bino-viewers.  grin.gif

 

Jeff


Edited by Jeff B, 30 October 2018 - 01:05 PM.

  • Galicapernistein likes this

#42 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 30 October 2018 - 02:57 PM

Careful! You're asking for advice from many of those who have been infected with aperture fever!

 

I think the best 6" f/8 is an 8" f/6, and of course a 10" has 56% more light grasp than that... and a 12" might be enough for the fainter DSO's....

 

Actually 10" is a very capable scope and still quite portable for the reasonably fit. A tube for a 10" f 4.7 fits neatly across most automobile rear seats too.

 

I still think you should negotiate a bit with your dad. See if you can get a 10" dob sooner by saving and paying for part of it yourself.  Pique his interest as well by saying you heard on Cloudy Nights that the Orion Nebula in Winter (or the Lagoon Nebula in Summer) shows nice feathery structure in a 10" dob at low power... 


Edited by jtsenghas, 30 October 2018 - 02:59 PM.

  • Shneor likes this

#43 25585

25585

    Apollo

  • *****
  • Posts: 1281
  • Joined: 29 Aug 2017

Posted 01 November 2018 - 02:56 PM

My Bresser 10" F5 is the only one that goes out to sites.

 

Its simple enough to buy mirrors of an aperture and focal length, but to get a tube, mount etc as a whole is more difficult, unless you go DIY.

 

So say choose 10 inch F6, Dad buys the mirrors, cel etc. Then you & he possibly can build your own custom scope around them. 



#44 buckingham_hoo

buckingham_hoo

    Sputnik

  • *****
  • Posts: 30
  • Joined: 29 Apr 2014
  • Loc: Central Virginia

Posted 03 November 2018 - 11:37 AM

Thanks everyone, 10 inch is final
Clear skies

Great choice!



#45 tmichaelbanks

tmichaelbanks

    Sputnik

  • -----
  • Posts: 49
  • Joined: 11 Aug 2017

Posted 03 November 2018 - 11:50 AM

A 10-inch Dob is a great instrument, but I think the advice on seeing conditions and bringing your Dob to thermal equilibrium mentioned earlier in this thread cannot be stressed enough.

 

I live in southern New England where the skies are unsteady much of the time.  On those few nights a year when skies are dry, clear and steady (and the moon is not present), you can get very good planetary views with even an 8-inch Dob and a quality 6mm EP.  We're talking cloud belt swirls and transit shadows on Jupiter, an easy Cassini split on Saturn, and the polar cap and some surface features on Mars.  On nights with unsteady seeing, I like to say it's like looking through a pot of boiling water.

 

You will have to determine if the added weight, collimation, and cool-down of a 10-inch is worth the effort vs. a smaller aperture given the typical seeing under your skies.  If your skies are relatively dark and steady, I'm sure the views will be tremendous.



#46 SandyHouTex

SandyHouTex

    Soyuz

  • *****
  • Posts: 3625
  • Joined: 02 Jun 2009
  • Loc: Houston, Texas, USA

Posted 03 November 2018 - 12:27 PM

I had my 10” Skywatcher solid tube Dob out this morning and the Orion Nebula was outstanding. So was M41 on Canis Majorum. Last week Mars showed a ton of detail at 170X.

You’ll love the 10” Dob.

Edited by SandyHouTex, 03 November 2018 - 12:29 PM.


#47 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 03 November 2018 - 02:14 PM

You’ll love the 10” Dob.

+1

 

        - - the owner of a 10" dob



#48 OleCuss

OleCuss

    Surveyor 1

  • *****
  • Posts: 1897
  • Joined: 22 Nov 2010

Posted 03 November 2018 - 02:31 PM

I know, I know, aperture is hard to beat.

 

But sometimes what matters most is not aperture.

 

I've everything from 60mm to 12" aperture available.  When I was able to use the eyepiece (eye problems which may be mostly resolved in a few months) I usually had limited time.  This meant that my most-used instrument was my 80mm ED-Doublet spotting scope.  No cool-down and it would set up in seconds.  Lots of pleasure from using a scope like that.

 

Some day I'll likely build out a 20" mirror I have.  The problem is that it's 4" thick.  If I were to build it out and take the thing out for observing the cool-down might be such that I might not have good observing before 2 in the morning?

 

I'd also note that I once had a 6" (F/8) Dobsonian and set it up next to 12" Dobsonians from the same maker/seller and some people preferred the view through the 6"!!  Not as good light-gathering or potential resolution but the perceived contrast seemed to be better with the 6" (slower optics are often better optics).

 

Bigger is not necessarily better.



#49 jtsenghas

jtsenghas

    Soyuz

  • *****
  • Posts: 3565
  • Joined: 14 Sep 2014
  • Loc: The flatlands of Northwest Ohio --Bloomdale

Posted 03 November 2018 - 05:49 PM

I'd also note that I once had a 6" (F/8) Dobsonian and set it up next to 12" Dobsonians from the same maker/seller and some people preferred the view through the 6"!!  Not as good light-gathering or potential resolution but the perceived contrast seemed to be better with the 6" (slower optics are often better optics).

 

Bigger is not necessarily better.

When seeing is only mediocre,  a 6" does have an advantage that conditions are more stable due to the smaller "tube of light" being used. 6" is also a decent aperture for the brighter objects.

 

Still, 10" is a lot better for resolution and light grasp when conditions permit.  Oh, so many DSO can't be appreciated until you make at least that step up.

 

Aperture fever can peter out though for the work involved with managing the really big scopes, and I now some older folks step down to 8"in their later years to reduce the physical work involved with setup and teardown. For anyone reasonably fit I think 10"is just right!

 

        -- the owner of a 10" dob who is building a 12.5"



#50 Jond105

Jond105

    Surveyor 1

  • *****
  • Posts: 1550
  • Joined: 19 Feb 2018
  • Loc: Detroit

Posted 03 November 2018 - 09:38 PM



You’ll love the 10” Dob.


+2


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: dob, reflector



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics