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Hello Skyscanners,

I am in need of some advice :help:

After some serious thinking I want to go for a bigger scope. I like to buy a 10" dobson (preferably a 20" :icon_biggrin:) and hope its brings me a bit more light gathering than with my current 8". I know it is not much bigger but I really like it to stay portable. My storage space is in the attic so plenty stairs to take, so with that in mind I choose a 10"

When search for 10" dobsonian telescopes most websites say "56% more Light Gathering than 200mm" but will it be a noticeable difference compared to my 8"?

I would like to hear your experiences and advice, thanks in advanced.

greets Gert

 

 

 

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Many people say that you need a 4” increase in aperture to see a noticeable difference. I’m not sure I’m in that camp, a 10” will still show you more so if it’s the biggest you can comfortably go, why not?

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8 minutes ago, Eastman said:

 

When search for 10" dobsonian telescopes most websites say "56% more Light Gathering than 200mm" but will it be a noticeable difference compared to my 8"?

Hi Gert,

What are your skies like? Are they quite dark?

More aperture makes the biggest difference under darker skies in my experience. You are unlikely to notice a 50% increase in observable objects. A 10" dob though is probably the ideal compromise between aperture and portability. I keep one in my observatory, which is mainly for imaging, so that I can pull it out when the skies demand it.

Enjoy your new scope :)

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If the biggest you can manage is a 10". Then go for it , a 56% more light gathering ability is certainty a worthwhile increase. But a 12" seems to be a far more significant increase. And the 12" seems to be the Goldy locks aperture size, great light gathering ability, but still manageable. 

The smaller aperture increases are more significant, than when you get to larger scopes. So a 2" aperture increase, 8" to 10" . will be a lot more in percentage term that say going from a 18" to 20 " . Therefore a 56% light gathering increase from 8" to 10" will show up to the eye to a good degree

The best scope is the one that will be used. If the 10" is the most you can manage, then go for it👍

 

 

 

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11 hours ago, Tim said:

What are your skies like? Are they quite dark?

Thanks Tim, the skies are quite dark and sometimes I bring the scope uit to dark skies in the area.

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20 hours ago, Timebandit said:

 

The smaller aperture increases are more significant, than when you get to larger scopes. So a 2" aperture increase, 8" to 10" . will be a lot more in percentage term that say going from a 18" to 20 " 

 

Agreed :) 

Going from 8" to 10" is more like going from 16" to 20" which gives a quite noticeable improvement in image scale on those faint fuzzies.  

IOW I would also say..........go for it :thumbright:

 

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... and going from 6 to 8 inches is also a huge difference! But then I went to 12, then 16...  :D

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1 hour ago, Beulah said:

But then I went to 12, then 16...  :D

.....tempting!

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From 8"-10" there will be some noticed difference but if you can swing a 12" I know there would be a big difference . However I once viewed through a 10" at the Veil Neb with a 2" Televue EP 32mm and it had a magnificence view . A lot I credit to the TV EP and being in a dark area . Then again I saw the Veil with same EP in a 12" . Blew my mind !! If I had to choose over my 8" SCT now the only thing i'd choose is a 12" . Only i'm not there yet and might never be so right now my dream is a 12" zhumell dob . But last I checked every where is out of stock so I don't know what's going on or they are discontinued . Even the 10" dobs are out of stock :confused1: .  

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3 hours ago, Beulah said:

... and going from 6 to 8 inches is also a huge difference! But then I went to 12, then 16...  :D

.......so 20" soon then Sam? ;) 

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Hello everybody, thank you all for your comments and explanations.

Its very appreciated, I will also take a 12" in consideration. I think that the SW Skyliner 300p flextube when collapsed will be good to carry arround.

Thanks Gert

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1 minute ago, Eastman said:

Hello everybody, thank you all for your comments and explanations.

Its very appreciated, I will also take a 12" in consideration. I think that the SW Skyliner 300p flextube when collapsed will be good to carry arround.

Thanks Gert

Don’t forget that the flextube is heavier than the solid tube version...

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Hi Gert, I went from using an 8" scope to a 12" flex-tube and it was appreciably superior. The 8" sct I had been using became redundant and consequently sold. Visually it made a huge impact and either 10" or 12" is a gain. Concerning the manageability of the 300p flex-tube (manual version), it is a bit heavy, but adequately handled by one reasonably fit person and collapsed is quite ergonomic. Mine was kept upstairs and was OK to carry out to the car or set in the backyard.

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Shame your in the Netherlands as I've just gone from a 12" to a 16" and the 12" needs to go.

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I went from 10" to 15" - or a 1.5x diameter = 2.25× Area =  .88 mag gain.

I found it very noticeable for DSOs, and it is also my prefered instrument for planetary observing.

8" to 12" would be the same ratio increase :headbang: :evil: :grin:

I have kept the 10", but find I rarely use it.

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Not sure I would fancy dragging a 12” down from the attic every time! 10” used regularly will be better than 12” looking at the inside of the attic!

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A lot of this seems to be personal preference it seems. I have owned 10, 12 and 14 inch dobs and the ten inch was best for me.  I gave away the 14 inch last year because I preferred the portability of the 10 inch. Also I found the higher quality of my smaller dob outweighed the increase in brightness in the 14.  I would caution against going for something really large unless you are quite sure. I have a 20 inch and it only gets used very rarely whereas the smaller scopes are regularly under the stars.  My personal perspective, but I am sure you will have great enjoyment whichever way you go.

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For lightness for portability, would an ES truss be worth considering?

Similar in price to the non goto SW 300p flextube, but I'd imagine much better suited to stairs / storage needs perhaps?

https://www.teleskop-express.de/shop/product_info.php/info/p6879_Explore-Scientific-Ultra-Light-Dobsonian---aperture-305-mm---Generation-II.html

Edited by niallk
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1 hour ago, Stu said:

Not sure I would fancy dragging a 12” down from the attic every time! 10” used regularly will be better than 12” looking at the inside of the attic!

That's the thing, but I have some time to think. First I have to sell my 8". I will let you all know what its gone be!

Thanks again.

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Gert - I have been thinking along similar lines for many months (8" > 10 or 12"??) and for while convinced myself that 10" would be fine.  But I now favour the 125% extra light with a 12", and feel that I would regret not going for a bigger aperture increment.  So it's the 300P for me - although I don't know when!

However, if you have a practical problem of carting the thing round, then a 10" would be more suitable and would still give improved views.  Not startlingly so, but at least the 'scope would get used!

Doug.

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It may depend on your current appetite for aperture gain. As Doug indicates often the thinking is 8" to 10 or 12" and this was my own conundrum at a time that I became curious for the extra % light grasp. I would have settled for either, for similar reasons talked about. Perhaps if your attic (overlooked that thanks Stu for highlighting) has a steep stairwell, perhaps a 250mm would be safer to carry, lots of considerations. My aperture 'fever' has diminished since currently using a 350mm dob, I feel that it is enough, although I remain curious and interested to experience the views with larger aperture, such as opportunities if possible at star parties. My interest in aperture has actually gone into reverse and I equally enjoy an 200mm dob and small wide field refractors. The reasoning is that my personal appetite is for dark sky and a desire to take dark sky readings / go stargazing at increasingly remote locations.     

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Go for a 12". Enough light grasp and portability to boot. And portability is very important and that is one of the first sensibilities to go out of the window when aperture fever strikes. A 12" under a very dark sky will amaze you.

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I've had a few telescopes now. My 8 inch dob was fine to lift, but had no handles. Handles make such a difference. They don't all come with them and just making something more lift-able (think moving and handling training at work) makes it more possible to grab it more often. I fitted a handle to my 8 inch SCT so i could mount it with one hand. My 10 inch portaball weighs 20kgs (OMG) and doesn't come into 2 pieces like a dobsonian. BUT  it has 2 handles in just the right spot so getting it out is easy. HANDLES makes all the difference. FIY all the OOUK dobsonians are much lighter than SW types.

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6 hours ago, Eastman said:

Not sure I would fancy dragging a 12” down from the attic every time! 10” used regularly will be better than 12” looking at the inside of the attic!

IMHO, the most important point - weight and bulk of the scope. I'd stay with a 10", preferably a lightweight construction, e.g the 10" Sumerian with a total weight of 12 kgs, or something similar:

https://www.teleskop-express.de/shop/product_info.php/info/p8530_Sumerian-Optics-Alkaid-10--f-5-Dobson-Teleskop.html

Not cheap, but such a scope, a "lifetime instrument" would be used often and could be transported easily to other dark sky areas.

We all know about aperture fever; it's "residual syndrome", aperture fatigue, is less known, but insidious, discomforting, and expensive, and thus should be avoided ;-)

If I were allowed to keep only one scope, it would be the 8" f/4 Hofheim Instruments traveldob.

Stephan

Edited by Nyctimene
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1 hour ago, Nyctimene said:

 

We all know about aperture fever; it's "residual syndrome", aperture fatigue, is less known, but insidious, discomforting, and expensive, and thus should be avoided ;-

Stephan

Good point, Stephan.  I await the onset of eyepiece fatigue - it might save me some cash!

Back on topic, this has got me thinking yet again, and a 10" is looking more attractive - reasonable increase in light-gathering, easily manageable, and offering a noticeably larger FOV than a 12" (a very important consideration).  The Bresser Messier looks like a candidate.....

Doug.

Edited by cloudsweeper
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