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AT72 focus with a 2" diagonal?

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#1 CHASLX200

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Posted 10 August 2018 - 05:10 AM

So does 2" stuff come to focus for visual on a AT72? 



#2 starman876

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Posted 10 August 2018 - 06:28 AM

Don not know. Never had one.  I think I would have gone for the Tak 76 before I would have bought the AT72.  



#3 Garthid

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Posted 10 August 2018 - 06:48 AM

Don not know either but I have heard that the AT72 is a fine scope. At least it's not a Unitron.lol.gif


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#4 Jon Isaacs

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Posted 10 August 2018 - 06:59 AM

So does 2" stuff come to focus for visual on a AT72? 

I don't know about the AT-72EDll, never had one.  The original AT-72ED had a lot of extra back focus even with 2 inch eyepieces. I assume the same is true of the new version.

As far as the Tak 76 versus the AT-72ED: Chas, being a planetary type, might want the Tak.

Me, being both a planetary and deep sky type would go with the AT-72ED.  A 3 inch is easily outperformed on the planets by a larger but still manageable scope. The virtue of a scope this size is low power wide field.  The AT-72ED is capable of 6.1 degrees, the Tak 76 can do 4.4 degrees, less than my 4 inch.

Jon



#5 Garthid

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Posted 10 August 2018 - 07:11 AM

Seriously though, the light path would be approximately 110mm for an average 2 inch diagonal so you can subtract that from the focuser travel to give you an idea. My bet would be that, if it has a 2 inch focuser, it will most likely accommodate a 2 inch diagonal.


Edited by Garthid, 10 August 2018 - 07:16 AM.


#6 junomike

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Posted 10 August 2018 - 07:12 AM

So does 2" stuff come to focus for visual on a AT72? 

From my brief experience with one, yes.



#7 gwlee

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Posted 10 August 2018 - 12:55 PM

My previously owned AT72ED did. My current AT72EDII does. 



#8 daquad

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Posted 10 August 2018 - 02:21 PM

Mine does.  6.2 Degree field with 32 mm UO MK 80 Konig.

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Edited by daquad, 10 August 2018 - 02:23 PM.

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#9 CHASLX200

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Posted 10 August 2018 - 05:39 PM

I don't know about the AT-72EDll, never had one.  The original AT-72ED had a lot of extra back focus even with 2 inch eyepieces. I assume the same is true of the new version.

As far as the Tak 76 versus the AT-72ED: Chas, being a planetary type, might want the Tak.

Me, being both a planetary and deep sky type would go with the AT-72ED.  A 3 inch is easily outperformed on the planets by a larger but still manageable scope. The virtue of a scope this size is low power wide field.  The AT-72ED is capable of 6.1 degrees, the Tak 76 can do 4.4 degrees, less than my 4 inch.

Jon

I just want a small sweeper for ultra garb and go bro.  I think 27mm Pano will live in most of the time. Maybe even a 21mm Ethos if i feeling like sucking up the $600 smackers+ one cost used.

 

Don't think i would ever bother with planets with it.  Plus i got it's big brother the AT102ED.  But down the road the AT72 would make a great finder for the SW150ED.


Edited by CHASLX200, 10 August 2018 - 05:41 PM.


#10 gwlee

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Posted 10 August 2018 - 11:52 PM

I just want a small sweeper for ultra garb and go bro.  I think 27mm Pano will live in most of the time. Maybe even a 21mm Ethos if i feeling like sucking up the $600 smackers+ one cost used.

 

Don't think i would ever bother with planets with it.  Plus i got it's big brother the AT102ED.  But down the road the AT72 would make a great finder for the SW150ED.

I find the 27mm Panoptic is a good low power EP for the AT72ED2. It gives 16x, 4.1 degree TFOV, 19mm of eye relief, and a 4.5mm exit pupil without being too porky. I use a 7mm Delite with it for keeping track of the bright planets, their satellites, our moon, and the sun. Together, these two EP cover most of my uses of this scope. 


Edited by gwlee, 11 August 2018 - 12:03 AM.

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#11 terraclarke

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Posted 11 August 2018 - 01:21 PM

Don not know. Never had one.  I think I would have gone for the Tak 76 before I would have bought the AT72.  

Having had an AT72ED and having an FC76, I can tell you that the Tak is much better optically (and optically more versatile), and also that it is much, much larger- both longer (and wider) and heavier, and requires more stringent mounting requirements. As far as a 2” diagonal and 2” eyepieces, it seems to me that they did work, but they made the scope heavier and I don’t think it all fit in the case, (I could be wrong, mine has been gone for some time). 



#12 gwlee

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Posted 12 August 2018 - 12:09 PM

Having had an AT72ED and having an FC76, I can tell you that the Tak is much better optically (and optically more versatile), and also that it is much, much larger- both longer (and wider) and heavier, and requires more stringent mounting requirements. As far as a 2” diagonal and 2” eyepieces, it seems to me that they did work, but they made the scope heavier and I don’t think it all fit in the case, (I could be wrong, mine has been gone for some time). 

 

Terra,

I have an AT72ED2 now, and I am considering the FC76. Why do you say it’s more versatile?

Gary



#13 Lou Laderman

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Posted 12 August 2018 - 12:20 PM

To answer the original question posted, yes. I have a Baader clicklock diagonal with  my AT72EDll and have used it with 2” ethos and smaller eyepieces with the 1-1/4” adapter. Back focus is no issue. I found infocus was a problem with my pvs-7, but that got solved.


Edited by Lou Laderman, 12 August 2018 - 12:20 PM.


#14 CHASLX200

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Posted 12 August 2018 - 04:12 PM

Terra,

I have an AT72ED2 now, and I am considering the FC76. Why do you say it’s more versatile?

Gary

That Tak can do 100x per inch and is better for high power work.  


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#15 starman876

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Posted 12 August 2018 - 04:26 PM

Mine does.  6.2 Degree field with 32 mm UO MK 80 Konig.

I think I have a finder scope that size.  Had no idea it was that small.


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#16 gwlee

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Posted 12 August 2018 - 05:08 PM

That Tak can do 100x per inch and is better for high power work.  

My eyes have too many floaters to enjoy using more than 25x per inch. At a 1mm exit pupil, I switch to a larger scope if I want more magnification. 


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#17 CHASLX200

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Posted 12 August 2018 - 05:32 PM

I just don't have floaters.  Even at 600x in ETX 125 they don't bother me.



#18 gwlee

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Posted 12 August 2018 - 06:37 PM

I just don't have floaters.  Even at 600x in ETX 125 they don't bother me.

Besides floaters, anything smaller than a 1mm exit pupil is too dim to suit me, so that's the point I switch to a larger aperture. 

 

Here's a photo of the AT72ED2 in terrestrial mode a  2" Baader AMICI prism and a 27mm Panoptic on a light photo tripod and DwarfStar Mount.  I had a AT72ED before that would also handle 2-inch accessories, but didn't balance quite as well. Both scopes require a longer than stock vixen rail to come to balance with 2" accessories. 

 

Everything you see in the photo weights about 15#. With a 2-inch Everbrite Diagonal, it's my most portable astronomical configuration for grab and go. 

 

For more stability, I put the same scope and accessories on a DM4 mount and Oberwerke wooden tripod, which how normally use it around home. 

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Edited by gwlee, 12 August 2018 - 06:42 PM.

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#19 CHASLX200

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Posted 12 August 2018 - 06:44 PM

Besides floaters, anything smaller than a 1mm exit pupil is too dim to suit me, so that's the point I switch to a larger aperture. 

 

Here's a photo of the AT72ED2 in terrestrial mode a  2" Baader AMICI prism and a 27mm Panoptic on a light photo tripod and DwarfStar Mount.  I had a AT72ED before that would also handle 2-inch accessories, but didn't balance quite as well. Both scopes require a longer than stock vixen rail to come to balance with 2" accessories. 

 

Everything you see in the photo weights about 15#. With a 2-inch Everbrite Diagonal, it's my most portable astronomical configuration for grab and go. 

 

For more stability, I put the same scope and accessories on a DM4 mount and Oberwerke wooden tripod, which how normally use it around home. 

I got all kinds of rails from short to long. I have the older version that is the same color as my AT102ED. I would use it on my GP mount.



#20 gwlee

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Posted 12 August 2018 - 06:51 PM

I got all kinds of rails from short to long. I have the older version that is the same color as my AT102ED. I would use it on my GP mount.

I used a 7-inch rail for both scopes, which is more than long enough to balance both scopes with 2" accessories up to a 35mm Panoptic. Haven't tried any heavier EP with it. My AT72ED was white/gray. I have too rotate the scope in the rings a bit to get the focus knobs to clear the rail.  



#21 daquad

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Posted 12 August 2018 - 06:58 PM

DSCN1964.JPG

I think I have a finder scope that size.  Had no idea it was that small.

Also makes a great guide scope.  


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#22 terraclarke

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Posted 13 August 2018 - 09:55 AM

Terra,

I have an AT72ED2 now, and I am considering the FC76. Why do you say it’s more versatile?

Gary

My FC76 is soooo sooo much sharper optically, with far better color correction, and better contrast too. It really shines when doing planetary observations. If you did a side by side comparison, you wouldn’t need to ask the question. Plus, at F8 you can still get nice wide fields for star clusters, etc.

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#23 starman876

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Posted 13 August 2018 - 01:45 PM

I would have to agree with Terra  100% of her description of the Tak.  I have no experience with the AT.  After reading what she stated I have no interest of trying the AT.  I will stick with my Tak.


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#24 gwlee

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Posted 13 August 2018 - 01:49 PM

My FC76 is soooo sooo much sharper optically, with far better color correction, and better contrast too. It really shines when doing planetary observations. If you did a side by side comparison, you wouldn’t need to ask the question. Plus, at F8 you can still get nice wide fields for star clusters, etc.

Thank you. I have been experimenting with AT72ED/AT72EDII refractors for a few a few years to decide how well a small refractor suits my current observing site. At this point, I am considering replacing my AT72EDII with a sensibly perfect refractor between 3 and 4 inches, so your experience with both the AT72ED and the FC76 is particular useful. 


Edited by gwlee, 13 August 2018 - 01:51 PM.

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#25 Moondust

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Posted 13 August 2018 - 02:16 PM

My FC76 is soooo sooo much sharper optically, with far better color correction, and better contrast too. It really shines when doing planetary observations. If you did a side by side comparison, you wouldn’t need to ask the question. Plus, at F8 you can still get nice wide fields for star clusters, etc.

I don't know if you are talking about a AT72ED or a AT72ED 2 on this side by side comparison but I owned both and the (2nd version) is quit a bit better having higher grade glass. If you are talking about the first version I would totally agree,. the second version not so much. Just how much sharper can it possibly be? I think you may want to remove at least one of those soooo's. 


Edited by Moondust, 13 August 2018 - 02:17 PM.



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