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Pls help our family choose the right first serious 11" telescope

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#51 Don H

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Posted 22 September 2020 - 02:16 PM

To use a C11 on a rooftop, you will need to find a way to isolate your mount. If you just put the tripod on the roof, inside a dome, anything you look at will be shook up quite a bit in the eyepiece as you walk or move around. And those vibrations will ruin any attempt to use the camera. Typically, a long fl scope like that is mounted on a substantial concrete pier that is isolated from the building. You could do this by sending a column down through the house and to or beneath the foundation, but it would be a substantial expense. 


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#52 aeneas

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Posted 22 September 2020 - 03:27 PM

To use a C11 on a rooftop, you will need to find a way to isolate your mount. If you just put the tripod on the roof, inside a dome, anything you look at will be shook up quite a bit in the eyepiece as you walk or move around. And those vibrations will ruin any attempt to use the camera. Typically, a long fl scope like that is mounted on a substantial concrete pier that is isolated from the building. You could do this by sending a column down through the house and to or beneath the foundation, but it would be a substantial expense. 

Hi Don, yes - I am aware of that... I've asked my house builders to give me the details of the roof construction (waiting still for details); however it is very very sturdy built and a flat roof; although not concrete I am sure foundation is very solid. I was thinking to lay atop of the existing roof material another layer of either concrete or some other hard non-vibrating material in a circular format of the size of the observatory dome. I cannot pierce the house though (and my wife would kill me!) wink.gif


Edited by aeneas, 22 September 2020 - 03:32 PM.


#53 Tanager4

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Posted 23 September 2020 - 06:32 AM

 

I already bout "Getting Started: Long Exposure Astrophotography" (thanks @Tanager4 for advice)

You're welcome

 

 

will go with C11 1100 EDGE HD mounted on CGX-L

Great!

 

Vibrations as Don_H mentioned above is one thing. The other thing is heat. Sitting on top of a house, especially on concrete, that is radiating heat doesn't sound like the best idea to me for a permanent observatory, unless you have no other place to put it.

 

 

Anything else I am forgetting about that should be an essential part of the package?

Finderscope and Nikon T-ring since you're getting a reducer, presumably for AP with the D750.

 

 

Anything else I should consider as key filters / attachments etc. to make the system work?

 

Autoguider: what would be a decent autoguider for the C11?

If you meant AP, then this forum is not the right one to ask these questions.

 

I suggest that you first get the visual setup worked out -- mount / telescope / finder / eyepiece (you said you already have some) and reconsider your location choice.

 

Also regarding a dome, a different forum might be better suited.

 

Would strongly suggest you take it step by step. Despite your experience with the 130EQ, figuring out the above with the CGX and C11 alone will take you some time.


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#54 Achernar

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Posted 23 September 2020 - 04:41 PM

Hi Don, yes - I am aware of that... I've asked my house builders to give me the details of the roof construction (waiting still for details); however it is very very sturdy built and a flat roof; although not concrete I am sure foundation is very solid. I was thinking to lay atop of the existing roof material another layer of either concrete or some other hard non-vibrating material in a circular format of the size of the observatory dome. I cannot pierce the house though (and my wife would kill me!) wink.gif

There is another consideration to take account, or rather two. One is if you live where hurricanes and tropical storms are a fact of life, you'll need to plan for that to keep your telescope from getting damaged by wind driven water getting in. The other is normally looking over rooftops is to be avoided due to the warm or hot air rising off of it. If you're going to set up a rooftop observatory, you don't want a roof that radiates a lot of heat all night long. That can ruin the view all night long. There are materials that reflect away the Sun's heat, and will retain less heat. Ever notice how the professional observatories domes are covered with reflective materials? That is what you'll need to do for your roof top observatory.

 

Taras


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#55 aeneas

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Posted 25 September 2020 - 04:03 AM

I live in moderate climate area (mountainous area in Central Europe) have a passive house with climate control & roof is flat, covered with pebbles so radiation & extra heating is not a major issue. I've spent often time on the roof even during summer (flying drone etc.) and it's as cool as in the garden. 

 

As suggested by some members here, I have now opened another thread in the Cats & Casses forum to go more into the specifics of the set-up considering that the OTA was chosen, so sticking with C11 EDGE HD (and not going for a Dob or a Refractor at this stage).

 

I would welcome you to contribute further there: Help me choose right accessories for a new C11 EDGE HD.



#56 Tony Flanders

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Posted 25 September 2020 - 04:57 AM

Hi Don, yes - I am aware of that... I've asked my house builders to give me the details of the roof construction (waiting still for details); however it is very very sturdy built and a flat roof; although not concrete I am sure foundation is very solid. I was thinking to lay atop of the existing roof material another layer of either concrete or some other hard non-vibrating material in a circular format of the size of the observatory dome. I cannot pierce the house though (and my wife would kill me!) wink.gif

I think it's very unlikely that you can build a platform suitable for high-power visual observing and/or astrophotography without building a pier that extends down all the way from the roof to the ground. You should be fine at low power, however.


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#57 aeneas

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Posted 26 September 2020 - 02:39 PM

I've been reading a lot more about eyepieces... some members here already warned me about this, but now I'm finally starting to appreciate that my Plossl collection I have for the 130EQ will not do justice to this new set-up. If I already decide to invest into a serious OTA, it would do justice to make sure I accompany that with decent line of eyepieces. Based on what I've read so far it seems best options would be something like:

 

(A) TV Ethos line: 8mm + 13mm + 21mm combined with Celestron's 0,7X recucer and a 2X Barlow

 

(B) Nikon NAV HW 12.5mm (10mm) + 17mm (14mm) combined with Celestron's 0,7X recucer and a 2X Barlow

 

I wasn't able to find any real data on Nikon NAV HW eyepieces on Nikon's official site... so strange. Everything that can be found on these eyepieces is via resellers. Why is that? Are they discontinued?

 

For C11 EDGE HD: would either of these be more appropriate purchases considering the particular optics of the scope?

 

I have friends in Japan so I could purchase Nikon NAVs at a similar price as I would by locally here the TV Ethos - so to me they would come at a similar end-price. If we ignore price difference... should I go for Nikon?

 

...to add some extra background: we live in a suburban area with Bortle 4 and frequently go for weekends to Bortle 2 area.


Edited by aeneas, 26 September 2020 - 03:27 PM.


#58 Don H

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Posted 26 September 2020 - 03:40 PM

I have not seen Nikon eyepieces much in the US. And the 100 degree Ethos eyepieces are not comfortable for all users, and may be difficult for the children to use. They are heavy and the shorter focal lengths are going to give you very high power, especially on your rooftop. The 13mm Ethos may be the best of bunch for your scope, as far as ease of use, but it is still 215x and less than .5 degree fov, with an exit pupil of only 1.3mm. You might want to try TV Nagler eyepieces first, like a 22mm for almost 2/3 of a degree fov at 127x and a 2mm exit pupil. A 31mm Nagler will give you 90x and almost 1 degree, but it is a monster of an eyepiece. Still, with your long 2800mm FL, it will be your best bet for low power. That or a 41mm Pantoptic, which give 68x, but the same 1 degree field. I would forget about any Barlow, and I do not have any experience with a reducer. If you want higher power, a 16mm Nagler might be nice, 175x and a comfortable ep to view. Or a 13mm Nagler with the same mag as the Ethos, but a bit smaller fov and a whole lot less weight. If you stick with one brand, all eyepieces can be close to parfocal, which is nice.



#59 aeneas

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Posted 26 September 2020 - 04:08 PM

Further to complement the eyepieces, what kind of diagonal / prism would you recommend to pair in this set-up? I was reading up on it and it seems there are several decent options, such as Baader T2 Zeiss / Celestron / TeleVue Everbrite / AstroPhysics MaxBright / William Optics.

If I am leaning on Nikon or TV Ethos for the eyepieces, what would be a suitable diagonal that would not do unjustice connecting the eyepiece to the scope?



#60 aeneas

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Posted 26 September 2020 - 04:20 PM

I have not seen Nikon eyepieces much in the US. And the 100 degree Ethos eyepieces are not comfortable for all users, and may be difficult for the children to use. They are heavy and the shorter focal lengths are going to give you very high power, especially on your rooftop. The 13mm Ethos may be the best of bunch for your scope, as far as ease of use, but it is still 215x and less than .5 degree fov, with an exit pupil of only 1.3mm. You might want to try TV Nagler eyepieces first, like a 22mm for almost 2/3 of a degree fov at 127x and a 2mm exit pupil. A 31mm Nagler will give you 90x and almost 1 degree, but it is a monster of an eyepiece. Still, with your long 2800mm FL, it will be your best bet for low power. That or a 41mm Pantoptic, which give 68x, but the same 1 degree field. I would forget about any Barlow, and I do not have any experience with a reducer. If you want higher power, a 16mm Nagler might be nice, 175x and a comfortable ep to view. Or a 13mm Nagler with the same mag as the Ethos, but a bit smaller fov and a whole lot less weight. If you stick with one brand, all eyepieces can be close to parfocal, which is nice.

Thank you @Don for these comments. Why would you consider Ethos would be more difficult for some then Nagler? The size/weight I would think I should not worry about - this is why I chose CGX-L mount vs CGEM-II so I can take nearly unlimited load (75 lb load), but I may be mistaken in this thought?

I would assume 21mm Ethos should be similar to 22mm Nagler, but Ethos offering 100-degree apparent viewing field vs 82-degree of Nagler?

It seems weight-wise Nikon is similar to Ethos (even slightly heavier) but may reviews have commented even superior clarity...



#61 Don H

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Posted 26 September 2020 - 08:56 PM

Thank you @Don for these comments. Why would you consider Ethos would be more difficult for some then Nagler? The size/weight I would think I should not worry about - this is why I chose CGX-L mount vs CGEM-II so I can take nearly unlimited load (75 lb load), but I may be mistaken in this thought?

I would assume 21mm Ethos should be similar to 22mm Nagler, but Ethos offering 100-degree apparent viewing field vs 82-degree of Nagler?

It seems weight-wise Nikon is similar to Ethos (even slightly heavier) but may reviews have commented even superior clarity...

The 100 degree field is not comfortable for all viewers. Some find it hard to see everything in the lens without moving one's eye around the image. I have viewed through an 8 and 13mm Ethos, but not a 21. I enjoy the 13 with a friend's 16" f/4.5, but that is with a 3.9mm exit pupil at 141x and over .7 degree fov. I'm sure the 21 would probably be very nice in the C-11, but it might be easier for the kids to use less than 100 degree eyepieces. Actually, if you can afford to try them, maybe they will enjoy those, too. The 31 Nagler is the same weight as the 21 Ethos. The fov on the C-11 is .9 degree for the 31 and .75 for the 21. 

 

Since I do not own an SCT, you might want to ask about ep choices in the EP or SCT forums.




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