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Help me choose between these 4 Apo Refractors

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#1 Procyon

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Posted 11 January 2017 - 04:10 PM

Hello, I'm looking for an Apo refractor to use with a Nexstar 6/8 SE mount for solar observing with a Quark and for night time use. This refractor will be operating at F/30 since the Quark has a built in 4.2 Telecentric barlow for solar viewing. I also be binoviewing with it at least half the time.

 

I'm trying to understand the difference between these 4. Which one would you guys suggest?

 

1) Astro-Tech AT115EDT f/7 ED Triplet Refractor 13lbs/27.5" long without the dew shield

 

2) EXPLORE SCIENTIFIC CF 102MM F/7 TRIPLET 7lbs/23.75"

 

3) EXPLORE SCIENTIFIC 102MM F/7 ESSENTIAL SERIES APO TRIPLET 12lbs/23.75"

 

4) LUNT ENGINEERING 102MM F/7 ED DOUBLET (Supposedly the length and weight is top secret info, can't be found anywhere..)

 

I will very rarely be doing any astrophotgraphy..I'm confused about all these glass terms though, ED, CF, etc...Doublets have ED glass too now? 

 

Thanks refractor heads :) Ha, I never thought I'd get a refractor, but here I am! I've only used dobsons and sct's to date and a minor experiment with an AT72 which didn't impress me much, but that was under very light polluted conditions and 2 quick tryouts. Maybe for solar or at a dark site and a bit more aperture things will look better.


Edited by Procyon, 11 January 2017 - 04:52 PM.


#2 Starman81

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Posted 11 January 2017 - 04:16 PM

Could the 27.5" long Astro-Tech AT115EDT f/7 ED Triplet Refractor even be used effectively on the Nexstar 6/8SE mount? It will likely be too long and hit the base for any object above 20° high. 

 

Even the other 3 scopes are at risk of not having enough clearance! I say this because with my SE mount and 500mm f/l refractor (EON 80) + 2in diagonal there is barely any additional clearance...



#3 Procyon

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Posted 11 January 2017 - 04:50 PM

Could the 27.5" long Astro-Tech AT115EDT f/7 ED Triplet Refractor even be used effectively on the Nexstar 6/8SE mount? It will likely be too long and hit the base for any object above 20° high. 

 

Even the other 3 scopes are at risk of not having enough clearance! I say this because with my SE mount and 500mm f/l refractor (EON 80) + 2in diagonal there is barely any additional clearance...

Starman, you may have just sunk my battleship, lol.

 

I got an 11" ADM dovetail with special holes that allow for extension. The Edge 8 I was using was 14 lbs but would sag if I lifted it too too high. I think I should abandon the 115mm than, perhaps a 102mm might be ok? Are refractors very heavy on the top side?

 

Maybe option 2, the black ES refractor at 7lbs is a good choice? Is that even possible, an 4" APO at 7lbs?


Edited by Procyon, 11 January 2017 - 04:53 PM.


#4 junomike

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Posted 11 January 2017 - 05:21 PM

Any of the OP's choices will most likely be too heavy to balance properly (especially the Triplets).

 

Even an Evo Mount (slightly larger) used with a similar (smaller) OTA needs this creative solution.

 

Mike



#5 Chris G

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Posted 11 January 2017 - 05:24 PM

I had an SV85S years ago on a Nexstar mount that was too long, I'd keep it to an 80mm or smaller.  The FC76 would be great. 


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#6 astrosky123

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Posted 11 January 2017 - 07:04 PM

yep i agree probally 80mm and no longer then f/6

j



#7 astrosky123

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Posted 11 January 2017 - 07:05 PM

i could aslo see a 90mm to 102 mak also fitting but thats not what u asked for


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#8 Procyon

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Posted 11 January 2017 - 07:46 PM

I will need an F7 to equal F30 with the 4.2x telecentric barlow. Thanks for the suggestions.

 

I'm researching about 102mm refractors used on Nexstar mounts and seeing mixed results. There are some users who say have succeeded though. Other's have used some type of Ron's rail extension.

 

Starman81, what ever happened to your experiment here?  :lol:  http://www.cloudynig...xstar-se-mount/

 

Other pictures here with 102mm success:  http://www.cloudynig...o/#entry4590197

 

This looks like a good refractor, a user just told me he had it successfully attached to the Nexstar. http://www.365astron...-Telescope.html

 

Coolest looking color I've ever seen for a refractor. Do any red 102mm triplets exist?

 

Maybe some refractors have different dovetail positionning and are easier fitted?


Edited by Procyon, 12 January 2017 - 11:40 AM.


#9 Procyon

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Posted 11 January 2017 - 07:54 PM

Ah here's a nice solution: and it's with that same KSON scope. Super.

 

"I regularly mount my Kson 1026ED (focal length 612) on my 6/8SE mount.

I place a short extension tube (Celestron x2 Barlow with the lens cell removed) into the diagonal and this allows me to reach zenith and not collide with the mount base ;-)

Gotos are accurate and the scope is pretty much balanced.

I'm sure something similar could be done with any short focal length refractor under 100mm.

One other point my scope is carbon fibre so it is very light (OTA =5.7lbs). Makes a great G&G.

I'll post a photo when I get home."

 

https://stargazerslo...6se-goto-mount/

 

Seems like Carbon Fibre will be the way to go.


Edited by Procyon, 11 January 2017 - 07:55 PM.


#10 Jon Isaacs

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Posted 11 January 2017 - 08:03 PM

4) LUNT ENGINEERING 102MM F/7 ED DOUBLET (Supposedly the length and weight is top secret info, can't be found anywhere..)

 

 

The Lunt 102mm F/7 ED doublet is essentially the same scope as the Astro-Tech AT-102ED, the StellarVue 102ED, the Orion 102 ED Premium and several others.  

 

 

Review of the AT-102ED

 

AT102ED_html_m1b6b5e8a.gif

 

Jon


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#11 Starman81

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Posted 11 January 2017 - 11:22 PM

 

Starman81, what ever happened to your experiment here?  :lol:  http://www.cloudynig...xstar-se-mount/

 

 

The Nexstar mount is still around but many refractors have come and gone. I like to be a little bit more free-wheeling with my refractors and go-to/tracking is not super important to me, so manual alt-az mounts are fine for me. But for your solar ambitions, the tracking is hand. You'll have to weigh scope size vs altitude range limitation. No getting around that!



#12 Procyon

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Posted 12 January 2017 - 06:03 AM

Looks like I have to scrap that KSON scope idea as it's an F6. I definitely need an F7 so will most probably get this carbon fibre one from ES:

https://www.astronom...ody_p20190.aspx

Or this one from Stellarvue: http://www.stellarvu...ctor-telescope/

Anyone use these?

Thanks

Edited by Procyon, 12 January 2017 - 06:35 AM.


#13 nicknacknock

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Posted 12 January 2017 - 10:21 AM

Procuon,

 

Whichever one you get, the Nexstar SE mount is not an option. The Evolution mount has more clearance though - perhaps worth investigating.


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#14 BigC

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Posted 12 January 2017 - 10:45 AM

You need a mount like the AVX. The SE are designed for SCT/MCT/AND MAYBE SHORT REFRACTOR.

Or possibly  an LCM if the scope weight is within its  limits.


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#15 nicoyenny

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Posted 12 January 2017 - 11:06 AM

Yes, i don't see how you can mix an SE mount with a 102mm APO. My mental image of the possible failure(s) is not pretty.

AVX screams "pick me!" and it is a soul mate for those scopes :)


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#16 RAKing

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Posted 12 January 2017 - 02:02 PM

I had an SV85S years ago on a Nexstar mount that was too long, I'd keep it to an 80mm or smaller.  The FC76 would be great. 

Agreed. I used an Astro-Tech 80mm on mine and it worked fine.  I was able to shove it forward enough to clear the diagonal at zenith.

 

The larger scopes the OP has proposed are too long, IMHO.

 

Cheers,

 

Ron

 

AT80-SE0808.JPG

 

AT80-SEa.JPG


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#17 Procyon

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Posted 12 January 2017 - 02:31 PM

Thanks for the pictures. Do you know how much clearance was left from the mount to the diagonal when at zenith?

 

I wonder if this little son of a gun will fit: https://www.optcorp....sv-focuser.html

 

It's 19.5" instead of the 102mm's 23.5", 6.8 lbs.

 

The carbon fiber ones eliminate any problem with weight at 7lbs, so I need to worry about the length now.


Edited by Procyon, 12 January 2017 - 04:31 PM.


#18 nicoyenny

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Posted 12 January 2017 - 02:57 PM

Cut the tube shorter = faster telescope!  :lol:



#19 spongebob@55

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Posted 12 January 2017 - 04:16 PM

 

I had an SV85S years ago on a Nexstar mount that was too long, I'd keep it to an 80mm or smaller.  The FC76 would be great. 

Agreed. I used an Astro-Tech 80mm on mine and it worked fine.  I was able to shove it forward enough to clear the diagonal at zenith.

 

The larger scopes the OP has proposed are too long, IMHO.

 

Cheers,

 

Ron

 

attachicon.gifAT80-SE0808.JPG

 

attachicon.gifAT80-SEa.JPG

 

Hi Ron,

What's that holder you have for the HC?  Home made?

Regards

SB



#20 Scott Beith

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Posted 12 January 2017 - 04:43 PM

You need a mount like the AVX. The SE are designed for SCT/MCT/AND MAYBE SHORT REFRACTOR.

Or possibly  an LCM if the scope weight is within its  limits.

This.  AVX or an older CG-5 ASGT.  The 115 would be a nice addition to anyone's collection.



#21 Procyon

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Posted 12 January 2017 - 04:53 PM

Do I need to extend the tube where the diagonal/focuser part is? How does this work with refractors? 

 

I found a picture I had taken of an AT72ED refractor I owned for a few weeks mounted on the Nexstar mount. That refractor was 14.5" long. I'm wondering if a refractor is 19.5" long how much of those extra 5 inches belong on the rear side?  :hmm:  :scratchhead:

 

But than there's the diagonal to add as well....ah forget it lol, I see what you guys mean now..I think only an extension will help me.

 

20141022_113432_resized.jpg


Edited by Procyon, 12 January 2017 - 04:56 PM.


#22 Procyon

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Posted 12 January 2017 - 05:38 PM

i could aslo see a 90mm to 102 mak also fitting but thats not what u asked for

You may be correct. If the 90mm doesn't fit I may just end up getting something like this: http://www.orionopti...maksutovca.html



#23 JohnAkai

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Posted 12 January 2017 - 08:07 PM

Procyon, Get the AT115, it offers one-third more light...⊙•)...CF = Calcium fluorite, the causative agent of Takititis ; - )


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#24 havasman

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Posted 12 January 2017 - 09:44 PM

I think only an extension larger mount will help me.

:waytogo: 

 

Or a smaller scope.


Edited by havasman, 12 January 2017 - 09:45 PM.

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#25 Procyon

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Posted 12 January 2017 - 09:57 PM

 

I think only an extension larger mount will help me.

:waytogo: 

 

Or a smaller scope.

 

  :fingertap:




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