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14" Dob - what to expect?

emadmoussa

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emadmoussa

emadmoussa

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I've got two choices: either to build an observatory or with my current budget upgrade my Dob and build a sliding shed to house it in the garden (semi observatory :) ).

I'm more likely to go with the second option.

While I love the flexibility and ease of use of a Dobsonian, I feel that it'll be great having a tracking capability. So I'm thinking of a motorized Dob.

16" will be large and too high, and for this reason I was thinking maybe a 14" is the way to go?

Any thoughts? How manageable is a 14"? Will the motors affect the manual mode in any way? Which is the best value for money, SW or Orion?

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Charic

Charic

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emadmoussa.........Hi, what are your skies like, if light polluted, then a 14-16" would be no better than my 8" under polluted skies. Building a shed is a great idea. If you sink a mount / pedestal into solid concrete and build your shed around that, you would isolate the scope from the shed, when your entering/leaving or just walking around the shed. and you can always build/modify a taller shed for taller scopes. But check the skies first.

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Charic

Charic

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why is it when you want something, you just cant find it? spent last 10 mins looking! There's a chap on here, just took a nice Image of Jupiter, but his link to his web site shows a shed build, which is what I was trying to describe above.

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emadmoussa

emadmoussa

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why is it when you want something, you just cant find it? spent last 10 mins looking! There's a chap on here, just took a nice Image of Jupiter, but his link to his web site shows a shed build, which is what I was trying to describe above.

No worries. I'm sure I can figure out how to do it. My main concern now is the practicality of a 14 inch Dob :)

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Moonshane

Moonshane

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emadmoussa.........Hi, what are your skies like, if light polluted, then a 14-16" would be no better than my 8" under polluted skies. Building a shed is a great idea. If you sink a mount / pedestal into solid concrete and build your shed around that, you would isolate the scope from the shed, when your entering/leaving or just walking around the shed. and you can always build/modify a taller shed for taller scopes. But check the skies first.

I don't agree with this at all. to my eyes, and based on my experience with newts from 4.5"-6"-8"-12"-16" all in light polluted areas, there's no doubt that any scope will be better at sites with no light pollution but in light pollution an 8" scope is still an 8" scope and a 14-16" scope is still a 14-16" scope. with a larger scope you will pick up more detail in star clusters and nebulae and fainter galaxies than a smaller scope. Also you have more potential for higher resolution on planets and splitting tighter doubles with a larger scope.

Don't get me wrong, an 8" scope is an excellent instrument but light pollution does not megate the benefits of aperture completely. there are some negatives to aperture of course (weight, cost, size, mirror cooling, collimation etc) but these have nothing to do with light pollution.

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Naemeth

Naemeth

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I'm afraid I agree with Shane on this one too, aperture matters whether you have no light pollution or a lot of light pollution (unless the object is dimmer than the light pollution - in that case not even Hubble could see through the LP).

Imad, have you considered an OO 16" (F/4) Dob? They are significantly lighter than their SW counterparts.

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swamp thing

swamp thing

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I'm kinda agreeing with both :rolleyes:

I kinda get what both are saying. LP is gonna stop a great deal of the advantage as the sky glow blocks a huge amount, but similarly the image scale of large scopes can still show more......great explanation huh :D

Basically what can be seen that's not hidden by the sky glow will always look better through a larger scope. If that makes any sense :D

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bingevader

bingevader

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emad, are you going for some Most Upgraded Kit in the Least Amount of Time award!?

I'm kinda agreeing with both :rolleyes:
I kinda get what both are saying. LP is gonna stop a great deal of the advantage as the sky glow blocks a huge amount, but similarly the image scale of large scopes can still show more......great explanation huh :D
Basically what can be seen that's not hidden by the sky glow will always look better through a larger scope. If that makes any sense :D

I got it.  :wink:

The low surface brightness objects suffer and the larger aperture gathers more LP too, but if you can see it, it will look better.

Cheers

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emadmoussa

emadmoussa

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emad, are you going for some Most Upgraded Kit in the Least Amount of Time award!?

I got it.  :wink:

The low surface brightness objects suffer and the larger aperture gathers more LP too, but if you can see it, it will look better.

Cheers

Not really. I'm talking in a year time.

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emadmoussa

emadmoussa

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Meaning 2013 has finished, now it's 2014? Woohoo!

LOL ...kinda!

I was planning on building on obsy after years of waiting, but it seems it'll be beyond my budget. So the idea of a roll in/out Dob will serve a similar purpose in terms of practicality and ease of use. And since this is going to be case - at least based on today's calculations - why not get a bigger aperture if moving kit around is not an issue.

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Charic

Charic

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I don't agree with this at all. to my eyes, and based on my experience with newts from 4.5"-6"-8"-12"-16" all in light polluted areas, there's no doubt that any scope will be better at sites with no light pollution but in light pollution an 8" scope is still an 8" scope and a 14-16" scope is still a 14-16" scope. with a larger scope you will pick up more detail in star clusters and nebulae and fainter galaxies than a smaller scope. Also you have more potential for higher resolution on planets and splitting tighter doubles with a larger scope.

Don't get me wrong, an 8" scope is an excellent instrument but light pollution does not megate the benefits of aperture completely. there are some negatives to aperture of course (weight, cost, size, mirror cooling, collimation etc) but these have nothing to do with light pollution.

Totally agree........but I read an article (not on SGL) from an authoritative, that in polluted areas ,and even some none polluted areas, there can be some limits to having bigger, and how practical the larger scopes are. I usually lecture to get a bigger aperture for the reasons you state, but the article (still searching for it) said something like  that the bigger the better, but also the better at magnifying and showing aberrations and pollution on a greater scale, and the article just made sense. If your scope is bigger better than mine, then in perfect conditions I'll lose, no contest, but if the seeing isn't so good one night. it could show worse in the bigger scope.

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emadmoussa

emadmoussa

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Totally agree........but I read an article (not on SGL) from an authoritative, that in polluted areas ,and even some none polluted areas, there can be some limits to having bigger, and how practical the larger scopes are. I usually lecture to get a bigger aperture for the reasons you state, but the article (still searching for it) said something like  that the bigger the better, but also the better at magnifying and showing aberrations and pollution on a greater scale, and the article just made sense. If your scope is bigger better than mine, then in perfect conditions I'll lose, no contest, but if the seeing isn't so good one night. it could show worse in the bigger scope.

And here comes the point of having more than one scope :D

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Charic

Charic

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I don't agree with this at all. to my eyes, and based on my experience with newts from 4.5"-6"-8"-12"-16" all in light polluted areas, there's no doubt that any scope will be better at sites with no light pollution but in light pollution an 8" scope is still an 8" scope and a 14-16" scope is still a 14-16" scope. with a larger scope you will pick up more detail in star clusters and nebulae and fainter galaxies than a smaller scope. Also you have more potential for higher resolution on planets and splitting tighter doubles with a larger scope.

Don't get me wrong, an 8" scope is an excellent instrument but light pollution does not megate the benefits of aperture completely. there are some negatives to aperture of course (weight, cost, size, mirror cooling, collimation etc) but these have nothing to do with light pollution.

True, but you  will also  gather/see as much, maybe  more light pollution in that equation, due to the larger capture of the larger aperture.

I'm afraid I agree with Shane on this one too, aperture matters whether you have no light pollution or a lot of light pollution (unless the object is dimmer than the light pollution - in that case not even Hubble could see through the LP).

Imad, have you considered an OO 16" (F/4) Dob? They are significantly lighter than their SW counterparts.

...........Using a big scope to see the  faintest  objects from a light-polluted city wouldn't make a lot of sense anyway. you'll still gather/see more light pollution.

I'm kinda agreeing with both :rolleyes:

I kinda get what both are saying. LP is gonna stop a great deal of the advantage as the sky glow blocks a huge amount, but similarly the image scale of large scopes can still show more......great explanation huh :D

Basically what can be seen that's not hidden by the sky glow will always look better through a larger scope. If that makes any sense :D

It makes sense to me......... Its true that the larger the aperture the brighter the image, which is better for DSO's but the larger the aperture  the greater the effects whether in perfect or not so perfect conditions on the larger telescope. I would also have continued that although emadmousssa is looking at an observatory, if the skies were too polluted, then the bigger scopes would be more of an effort to transport to a temporary darker site.

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