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Aperture Fever? 8" vs 10" or 12"

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#101 25585

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Posted 19 February 2019 - 02:14 PM

I really don't see any difference in terms of sitting versus standing between a 10 inch F/5 versus a 12 inch F/5.  Both are too short to allow standing and both are best when the observer sits on an adjustable chair such as the Starbound.

 

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True, but upright the 60 inch is less painful, by 10 inches, for standing observing. Ideally for height a 12 F6 would be ideal.


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#102 stargazer193857

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Posted 19 February 2019 - 06:33 PM

True, but upright the 60 inch is less painful, by 10 inches, for standing observing. Ideally for height a 12 F6 would be ideal.


Depends what part of the sky you are looking at.
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#103 Jon Isaacs

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Posted 20 February 2019 - 06:41 AM

True, but upright the 60 inch is less painful, by 10 inches, for standing observing. Ideally for height a 12 F6 would be ideal.

 

How much time have you spent with a scope with a 72 inch focal length?

 

My 16 inch has a 70.7 inch focal length, my 13.1 inch has a 71.9 inch focal length.  In my experience, for someone 6 foot tall, there's a reasonable part of the sky that can be observed standing but most of the sky will require stooping or sitting.  And I think sitting is preferable to standing.  The upper body is more stable when seated, standing without something to lean on (a steel ladder), tracking is more difficult and there is more motion at the eyepiece because your head is not not as well supported. With an adjustable chair, the viewing position is always optimal.  

 

With a 60 inch focal length, I can use a Starbound chair at all elevations.  With a 72 inch focal length, it takes the somewhat clunkier Catsperch Pro.. 

 

5838018-Catsperch with Dobstuff Dob.jpg
 
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#104 stargazer193857

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Posted 20 February 2019 - 12:47 PM

My knees are bad. And when I looked through a 12" Meade Light bridge aimed at 40 degrees, I was stooping and wished I had a chair real quickly. The folding stool I brought was not tall enough.

12" puts up a good view and is still wide enough to find stuff, though 10" finds stuff better. A good finder is best.

#105 DNA7744

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Posted 20 February 2019 - 07:26 PM

Well Gang...I've got enough saved from my p/t job at the ski area that I could pull the pin and purchase the 10" ES Truss Dobson today....or (thanks to the never ending snow) I've been getting extra hours that I should have enough saved for the 12" by the end of next week (and prior to the alleged price increases on March 1st--Tariffs??).  What to do?  Buy the 10" and have a few extra bucks for accessories...or wait for the ES 12" in a week?



#106 Jond105

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Posted 20 February 2019 - 08:03 PM

Well Gang...I've got enough saved from my p/t job at the ski area that I could pull the pin and purchase the 10" ES Truss Dobson today....or (thanks to the never ending snow) I've been getting extra hours that I should have enough saved for the 12" by the end of next week (and prior to the alleged price increases on March 1st--Tariffs??). What to do? Buy the 10" and have a few extra bucks for accessories...or wait for the ES 12" in a week?


Save and get the 12". Reason being, not a whole lot of weight difference I think between the two. I could be mistaken but believe that's what I read when I checked their specs last time. Plus, no one knows what the price on the 12" would raise to. Could be a $100 could be more. If more, then you still have the money for the 10" and accessories. Just wait and see sort of thing.

That said the 10" still grabs a lot of light, and you'd be able to get some eyepieces if you need them. But I wish sometimes I grabbed the 12" over the 10". I'm still grateful for the 10" though.
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#107 Earthbound1

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Posted 20 February 2019 - 08:13 PM

For me the question is how well will it fit through the doorway and how heavy is it, if it only costs a hundred or two more... After thinking on that set of criteria a 12" one seems ideal for me at this time.

#108 Pierre Lemay

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Posted 20 February 2019 - 10:36 PM

A good finder is best.

Speaking of finders... Unless one is using a GOTO or a laser to point the telescope, a finder scope is needed. All very nice to discuss eyepiece height, position and observing comfort but don't forget the ergonomics and comfort of finding objects with a straight through finder, be it optical or reflex sight.

 

I normally use a Telrad or Rigel when hunting objects and if the tube is too short, I have a lot of trouble contortioning myself when trying to find objects near the zenith. That's what I like about 72 inch focal length tubes: I can position the reflex sight high up on the upper ring yet the eyepiece is still fairly close to the ground to not need a very tall ladder.


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#109 DNA7744

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Posted 20 February 2019 - 10:48 PM

Speaking of finders... Unless one is using a GOTO or a laser to point the telescope, a finder scope is needed. All very nice to discuss eyepiece height, position and observing comfort but don't forget the ergonomics and comfort of finding objects with a straight through finder, be it optical or reflex sight.

 

I normally use a Telrad or Rigel when hunting objects and if the tube is too short, I have a lot of trouble contortioning myself when trying to find objects near the zenith. That's what I like about 72 inch focal length tubes: I can position the reflex sight high up on the upper ring yet the eyepiece is still fairly close to the ground to not need a very tall ladder.

Yes...I have a Rigel on my SW-8" Dobson (works fantastic)...and plan to replace the red dot finder on the ES with a Telrad.



#110 Allan Wade

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Posted 21 February 2019 - 04:31 AM

Well Gang...I've got enough saved from my p/t job at the ski area that I could pull the pin and purchase the 10" ES Truss Dobson today....or (thanks to the never ending snow) I've been getting extra hours that I should have enough saved for the 12" by the end of next week (and prior to the alleged price increases on March 1st--Tariffs??).  What to do?  Buy the 10" and have a few extra bucks for accessories...or wait for the ES 12" in a week?

Spend the money on the 12" now, and then save for the accessories later. I had a 12" Orion dob I optimised and it was a seriously good deep sky telescope. 12" of aperture gives you some serious performance and you move into a sky filled with a lifetime of satisfying observing.



#111 starcanoe

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Posted 21 February 2019 - 09:19 AM

IFFFFF the 12 does NOT cross the threshold of being a bit too heavy and or bulky to get out the door of the house or to carry out into the yard...or fit into the car (preferably while assembled) to take to a distant observing site....then IMO hold out for a bit and get the 12.

 

A 12 incher collects 44 percent more light than a 10 incher. Given the non linear response of the eye to light it is not as much as it sounds but it does help a little bit. OTOH...when you consider resolution in 2 dimensions (ie not double stars)....like looking at tight star clusters...bright detailed nebula...globular clusters...planets...and the moon...it also means you have 44 percent more "pixels" on the object. That is signifcant. Imagine (or if you have been using computers awhile) a computer screen or digital camera image where you can see the pixels...not bad perhaps but if you look you can notice them. Now imagine you have 44 percent more. You'll notice the improvement.

 

Rig yourself up some wheels on the scope or get yourself a dolly...or make a custom one. Just being able to easily wheel the scope outside will likely increase the amount of times you'll bother to take the scope outside to use it.

 

A 12 incher is the largest of the "small scopes". A sixteen incher is the smallest of the "big scopes". 13, 14, and 15 inchers are the red headed step children of the scope world. That or they look suspiciously like the mailman.


Edited by starcanoe, 21 February 2019 - 09:21 AM.

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#112 DNA7744

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Posted 21 February 2019 - 10:04 AM

IFFFFF the 12 does NOT cross the threshold of being a bit too heavy and or bulky to get out the door of the house or to carry out into the yard...or fit into the car (preferably while assembled) to take to a distant observing site....then IMO hold out for a bit and get the 12.

 

A 12 incher collects 44 percent more light than a 10 incher. Given the non linear response of the eye to light it is not as much as it sounds but it does help a little bit. OTOH...when you consider resolution in 2 dimensions (ie not double stars)....like looking at tight star clusters...bright detailed nebula...globular clusters...planets...and the moon...it also means you have 44 percent more "pixels" on the object. That is signifcant. Imagine (or if you have been using computers awhile) a computer screen or digital camera image where you can see the pixels...not bad perhaps but if you look you can notice them. Now imagine you have 44 percent more. You'll notice the improvement.

 

Rig yourself up some wheels on the scope or get yourself a dolly...or make a custom one. Just being able to easily wheel the scope outside will likely increase the amount of times you'll bother to take the scope outside to use it.

 

A 12 incher is the largest of the "small scopes". A sixteen incher is the smallest of the "big scopes". 13, 14, and 15 inchers are the red headed step children of the scope world. That or they look suspiciously like the mailman.

I plan on keeping my 8"...mostly for ease of use and primarily for the winter (quick carry out to the back deck).  The base of the12" (I think I am convinced that is the one) is a little over 17" which is about the same size as my 8" base...so no problem carrying it out the back sliding glass door to the deck...and will be primarily used during the warmer months where I can sit out and do extended viewing!  At least that is the plan!



#113 Jon Isaacs

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Posted 21 February 2019 - 10:58 AM

Speaking of finders... Unless one is using a GOTO or a laser to point the telescope, a finder scope is needed. All very nice to discuss eyepiece height, position and observing comfort but don't forget the ergonomics and comfort of finding objects with a straight through finder, be it optical or reflex sight.

 

I normally use a Telrad or Rigel when hunting objects and if the tube is too short, I have a lot of trouble contortioning myself when trying to find objects near the zenith. That's what I like about 72 inch focal length tubes: I can position the reflex sight high up on the upper ring yet the eyepiece is still fairly close to the ground to not need a very tall ladder.

 

I use two finders on all my Dobs,  a Telrad and a 50mm-80mm RACI finder.  With shoter scopes like the 10 inch F/5 or the 12.5 inch F/4.06, the key to comfortably using a straight through finder,  either a Telrad or a magnifying finderfinder , is an easily adjustable chair (Starbound)  and carefully placed finders. 

 

GSO Dob Base refinished.jpg
Finder Placement 16 inch Dobstuff.jpg
 
Jon


#114 DNA7744

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Posted 22 February 2019 - 03:11 PM

Well I just made the purchase for the ES 12" truss directly from Explore Scientific. Got a 10 percent discount on the purchase! Now just have to wait for delivery! (And good weather!)
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#115 F.Meiresonne

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Posted 22 February 2019 - 04:42 PM

Good thing.

Going up from 8 to 10 is not really worth it , indeed the 12 inch is much better.

 

And about the weather, sorry , first couple of weeks it will be bad, good it is only a 12 inch, should d it have been 18' , it would be good for months of clouded skieslol.gif

 

Just kidding

I hope you can enjoy it asapwink.gif

 

hm well ,just noticed you are in CA, bad weather is not very likely, at least not for long , i thinksmirk.gif


Edited by F.Meiresonne, 22 February 2019 - 04:46 PM.

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#116 AnalogKid

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Posted 24 February 2019 - 08:03 AM

As someone here told me last year when I was contemplating between a 10" and a 12" coming from an 8".....When using the 12" you won't say, gee I wish I would have gotten the 10"


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#117 stargazer193857

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Posted 25 February 2019 - 10:04 PM

As someone here told me last year when I was contemplating between a 10" and a 12" coming from an 8".....When using the 12" you won't say, gee I wish I would have gotten the 10"

Definitely true when looking through it. When moving it or thinking about moving may be a different story.

That said, my friend and I think a 12" gives the most bang for the effort, if you can safely move it.

I bet I could move a 12" solid if I pay Dennis at Dobstuff to make a square base. But my plan is custom 11" f5.

For me it is a question of how big a field of view do I want without needing a bigger eyepiece and how tall of a chair do I want to sit on. Taller folk will prefer the 12.


Some people feel 10" f4.7 is too short. Ergonomics, not just view and transport.

Edited by stargazer193857, 25 February 2019 - 10:19 PM.


#118 Jon Isaacs

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Posted 26 February 2019 - 07:14 AM

Definitely true when looking through it. When moving it or thinking about moving may be a different story.

 

 

:waytogo:

 

I am always surprised just how big a 12 inch F/5 is when compared to a 10 inch F/5.  A 10 inch is an easily moved scope, the 12 inch, not so much.  That is one reason why I have kept my 10 inch F/5.  It has never been my biggest scope, never been my "best" scope but it gets a lot of use.  I think a 10 inch F/5 is a sweet spot.  

 

Jon


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#119 DNA7744

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Posted 26 February 2019 - 11:35 AM

My ES 12" truss is on the truck set for delivery later this week!
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#120 Jon Isaacs

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Posted 26 February 2019 - 11:44 AM

My ES 12" truss is on the truck set for delivery later this week!

Excellent.  And the new moon is rapidly approaching. 

 

Big Bear is dark enough you should have some great views right there.

 

Jon



#121 DNA7744

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Posted 26 February 2019 - 01:32 PM

Excellent.  And the new moon is rapidly approaching. 

 

Big Bear is dark enough you should have some great views right there.

 

Jon

I know...and the Orion Nebula (M42) is in a perfect spot right after sunset from my back deck (before it disappears into the trees).  Anxious to get it assembled, and out on the deck to compare M42 with the 12" vs my 8"!


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#122 25585

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Posted 02 March 2019 - 08:57 AM

waytogo.gif

 

I am always surprised just how big a 12 inch F/5 is when compared to a 10 inch F/5.  A 10 inch is an easily moved scope, the 12 inch, not so much.  That is one reason why I have kept my 10 inch F/5.  It has never been my biggest scope, never been my "best" scope but it gets a lot of use.  I think a 10 inch F/5 is a sweet spot.  

 

Jon

F5 10" fit in cars much easier.

 

But for height I like long. Even diagonal it means I am less likely to kick the stand. So have height adjustable platforms for use as needed.



#123 DNA7744

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Posted 02 March 2019 - 09:29 AM

My ES 12" Truss Dobsonian arrived yesterday and I spent nearly 5 hours (with breaks) carefully assembling it.  Obviously, I need to get the assembly down to an average of 15 minutes or so...as has been posted on CN before.  It is massive compared to my SW 8" Collapsible Dobsonian.  And now we have a weeks worth of storms rolling through so not much chance to see it in action!  



#124 Jon Isaacs

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Posted 02 March 2019 - 09:49 AM

F5 10" fit in cars much easier.

 

But for height I like long. Even diagonal it means I am less likely to kick the stand. So have height adjustable platforms for use as needed.

 

I don't quite understand, you manage to kick the base somehow?  I cannot remember that having happened in the nearly 20 years I have been observing with Dobs.  When seated, the chair is not necessarily facing the scope.  

 
4657578-12.5 inch Dob at 45 deg sitting on the Starbound.jpg

 

Jon



#125 stargazer193857

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Posted 02 March 2019 - 05:18 PM

A 10" base won't fit in small car trunks. It is 21-22" in diameter. Small and mid Suze trunks are about 18.5" tall. The 8" has an 18" base. That's why I keep ragging on the particle board fold to make square off their bases past 18".


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