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The AT92

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#1151 Diana N

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Posted 12 November 2019 - 11:08 AM

Thanks for the wonderful and thorough review, Tyson!  Like you, I plan to use my AT92 visually, so your eyepiece recommendations are especially valuable.  I'm still waiting for my 2" star diagonal and the Vixen finder shoe to arrive (both are backordered at the moment), so my scope hasn't caught any starlight yet.  Needless to say, I'm impatient!

 

(I also wish that more visual observers would comment on the various apo and ED refractors available.  Not everyone buys a refractor solely to hang a camera off of it!)


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#1152 Tyson M

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Posted 12 November 2019 - 12:09 PM

Thanks for the wonderful and thorough review, Tyson!  Like you, I plan to use my AT92 visually, so your eyepiece recommendations are especially valuable.  I'm still waiting for my 2" star diagonal and the Vixen finder shoe to arrive (both are backordered at the moment), so my scope hasn't caught any starlight yet.  Needless to say, I'm impatient!

 

(I also wish that more visual observers would comment on the various apo and ED refractors available.  Not everyone buys a refractor solely to hang a camera off of it!)

Good choice on using a 2" diagonal.  Otherwise you will be racking out the focuser quite far, possibly need an extension tube. 

 

You don't really need the finder shoe IMO, I don't use a finder scope and it will add weight to the backend.  Up to you though.



#1153 Diana N

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Posted 12 November 2019 - 12:58 PM

Good choice on using a 2" diagonal.  Otherwise you will be racking out the focuser quite far, possibly need an extension tube. 

 

You don't really need the finder shoe IMO, I don't use a finder scope and it will add weight to the backend.  Up to you though.

Whether or not a scope will need an extension tube for visual observing when fitted with a 2" star diagonal is one of those things I wish would be mentioned in refractor reviews.

 

I'm planning to use the finderscope shoe to mount either a Telrad or (much more likely) a Rigel Quikfinder (using the adapters that Scopestuff sells for that purpose).  So I won't be adding too much in back weight on the scope, especially since I'm not a fan of massively heavy eyepieces that can double as hand grenades in the unlikely event my dark sky site should come under assault by enemy troops. grin.gif  (Of course, having said that I will no doubt discover that I will need those heavy eyepieces to get decent views with this fast scope!)


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#1154 Astrojedi

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Posted 12 November 2019 - 01:06 PM

My dream refractor is an NP101.  But I'd gladly spring for an AT92 if/when a dedicated field flattener/reducer comes out for it.

The fact it's airline portable is a huge plus vs. the NP-101.  Ditto price.

Clear Skies,

Phil

Ditto... If there was a dedicated field flattener I would buy it right away. Unfortunately Astronomics has not indicated any interest so far in producing one.



#1155 Diana N

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Posted 12 November 2019 - 01:09 PM

Ditto... If there was a dedicated field flattener I would buy it right away. Unfortunately Astronomics has not indicated any interest so far in producing one.

Way back in this thread some folks have mentioned that TS makes a field flattener that apparently works well with this scope, if that helps.



#1156 IMB

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Posted 12 November 2019 - 01:11 PM

 <...> The main reason why this scope is attractive to me, is that it fits into a photo backpack as its overall length is only 16". <...>

<...> This scope is the perfect travel scope, when the primary concerns are fitting the largest aperture in the smallest package. <...>

<...> Portability and versatility are the name of the game with these scopes, and that matters a lot when it comes to observing. <...>

Tyson, thank you very much for your review. Your opinion is very valuable to me, since I've been looking for a new travel scope since May, and the AT92 is a strong contender (another contender is the TS90; it's slightly longer than the AT92 at 500 mm, but it comes with a splittable tube). Looking forward to your new observation reports with the AT92. Is there any chance for you to do observations using eyepieces from the ES82 line?


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#1157 Astrojedi

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Posted 12 November 2019 - 01:16 PM

Way back in this thread some folks have mentioned that TS makes a field flattener that apparently works well with this scope, if that helps.

Thanks. Actually the Astronomics flattener also works decently with the At92 but the image quality can be better. I would like a dedicated flattener matched to the optics for best optical quality and 42mm sensor coverage.



#1158 jupiter1

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Posted 12 November 2019 - 09:19 PM

My AT92 (#79) arrived 11/4.  Unfortunately due to an ordering mixup my mount hasn't arrived yet. Weather clouded up on schedule when it arrived anyway so there's that. At this time I plan on visual only and will be using 1.25" eyepieces and diagonal. Given my other scope is a 15" f4.5 dob, the 3°+ field of a 24 Panoptic should satisfy me for a while.

 

  AT92 f5.5 & eps.jpg

 

In regards to Tyson's comments about 2" diagonals and racking out the focuser, I'm thinking mine is going to have to be racked out about 60mm with the 1.25" diagonal and 24 Pan. Also I like keeping it simple; the 24 Pan and 5, 7 & 9mm T6 Naglers are all parfocal and weigh essentially the same so there shouldn't be any balance issues (except when I use the 2.5x powermate) and minimum refocusing. I have a hole to fill between the 24 and the 9, I'll decide on that after I get to use the scope. A 15mm DeLite or 13mm T6 Nagler sounds about right. Also considering a 32 plossl for brighter field. This is my first quality refractor so I'm looking forward to first light. Which btw will be at least another week and a half because I have to head out of town and the scope can't go.

Steve


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#1159 Tyson M

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Posted 12 November 2019 - 09:26 PM

Tyson, thank you very much for your review. Your opinion is very valuable to me, since I've been looking for a new travel scope since May, and the AT92 is a strong contender (another contender is the TS90; it's slightly longer than the AT92 at 500 mm, but it comes with a splittable tube). Looking forward to your new observation reports with the AT92. Is there any chance for you to do observations using eyepieces from the ES82 line?

Its hard to say, that TS90 has a few points going for it as well. Looks like a good buy as well.  I havent had that exact scope, but I have experience with TS split tube apos, as I had the 72ED f5.5-  so I will comment on my experiences on that function.

 

The split tube function seems very good on paper, but some minor annoyances flared up while owning one for a while.  The paint seemed to chip and be missing in places around the threaded section, which was noticeable on the OTA once it was completely threaded together.  I was not happy with this when I bought a brand new scope to have paint sections missing, but it appear that more showed up over time.  Also, threaded the scope together in the dark can be risky at times (from cross threading, or dropping, ect).

You will also need to get lens coat hoodies to put on the section that has the lenses, as dust gets on the inside glass as it would be open to the atmosphere when disassembled. My hard fitting cap was also too loose on my TS72apo, so I had to buy another lens coat hoodie for the front of the objective lens side as well.  One could have put more felt inside it, but I was already getting a lens coat for the other side. You can and should carry a bulb blower with you when using any split tube scope.

 

Additionally, more importantly, you may find that one (or more possibly) eyepiece may not achieve focus like the rest of your line up.  This may mean you need to keep threading the section in and taking it out when using that eyepiece. Eyepieces that require more in focus will likely need the threaded section removed.  After a while, I stopped using the eyepiece that was causing me to do this as I didnt want to take off the scope from the mount once I started using it.

 

To speak on your last point, I will not be testing any ES82.  They typically don't have enough eye relief for me with glasses. 

The TS scopes can be very good.  All scopes I owned from them had great optics.  I believe SV imported those scopes for their own so it should  be no surprise many are good to great, with only the rare dud/lemon likely.

 

The TS90 will likely be better on your eyepieces though, at the edges anyways.  But then again I use Brandons on my AT92 (worst case scenario minimum glass)so the edges are noticeable but not too objectionable.  A TV32 plossl would be a better fit than my 32 or 24 Brandon if I was sticking with 1.25" eyepieces only (and still using a 2" diagonal). 

 

I think the build quality would be similar but likely a slight edge to the AT92. Both have nice focusers (that focuser on the TS90 apo is the premium dual speed SV focuser) likely equal in smoothness, but there may be paint specs missing on your threaded parts on the TS, and the AT92 has a twist lock compression fitting which is useful. Also see my comment about the hard lens cover with my TS72.

 

Optically, I think the AT with its minimum 95% strehl standard is a better bet to go. 

For convenience of not having to thread the scope together, again point for AT92.  I see 2.5 to 3 points to the AT92 over the TS's 1 point for being better on eyepiece periphery viewing for a longer focal length.

 

If you can get a 5% CN member discount, even better. 


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#1160 Tyson M

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Posted 12 November 2019 - 10:15 PM

My AT92 (#79) arrived 11/4.  Unfortunately due to an ordering mixup my mount hasn't arrived yet. Weather clouded up on schedule when it arrived anyway so there's that. At this time I plan on visual only and will be using 1.25" eyepieces and diagonal. Given my other scope is a 15" f4.5 dob, the 3°+ field of a 24 Panoptic should satisfy me for a while.

 

  attachicon.gif AT92 f5.5 & eps.jpg

 

In regards to Tyson's comments about 2" diagonals and racking out the focuser, I'm thinking mine is going to have to be racked out about 60mm with the 1.25" diagonal and 24 Pan. Also I like keeping it simple; the 24 Pan and 5, 7 & 9mm T6 Naglers are all parfocal and weigh essentially the same so there shouldn't be any balance issues (except when I use the 2.5x powermate) and minimum refocusing. I have a hole to fill between the 24 and the 9, I'll decide on that after I get to use the scope. A 15mm DeLite or 13mm T6 Nagler sounds about right. Also considering a 32 plossl for brighter field. This is my first quality refractor so I'm looking forward to first light. Which btw will be at least another week and a half because I have to head out of town and the scope can't go.

Steve

Congrats!  Be sure to share you visual/observing experiences here!  The Naglers should perform very well, as the pan.


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#1161 IMB

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Posted 12 November 2019 - 11:25 PM

What would be a good manual alt-az travel mount for the AT92?


Edited by IMB, 12 November 2019 - 11:50 PM.


#1162 Tyson M

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Posted 12 November 2019 - 11:39 PM

AZGTI, DSV1, Vamo traveller. Those are the ones that would come to my head.  I have a porta II I use but it is kind of bulky, Vamo is a bit smaller and lighter. 



#1163 rustynpp

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Posted 13 November 2019 - 09:49 AM

What would be a good manual alt-az travel mount for the AT92?

The Stellarvue MV1 works well with my C80ED, which, given the smaller aperture but longer FL, is probably comparable to the AT92 with regard to mount requirements. I think the weak point in my setup is the aluminum photo tripod, although even with that weak link I would call the whole thing reasonably stable. 

 

I've travelled with the MV1 mount before - it packed quite nicely into a DSLR backpack. See the right side of the 2nd photo below.

 

1.jpg

 

Lunt 5 (CN).jpg


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#1164 Phillip Creed

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Posted 13 November 2019 - 01:24 PM

Way back in this thread some folks have mentioned that TS makes a field flattener that apparently works well with this scope, if that helps.

Which page / field flattener?

Clear Skies,

Phil


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#1165 Diana N

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Posted 13 November 2019 - 01:39 PM

Which page / field flattener?

Clear Skies,

Phil

Found it!  It's mentioned in post #1135 by scooke on page 46:  https://www.cloudyni...at92/?p=9594717


Edited by Diana N, 13 November 2019 - 01:41 PM.

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#1166 jupiter1

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Posted 13 November 2019 - 07:46 PM

My AZ-GTi mount arrived today. Since SWMBO has me doing slave labor prior to my departure tomorrow I have only had time to mount the scope and use it manually briefly. The scope balances nicely, movement is smooth in altitude but fairly stiff in azimuth at this time. I'll see how that plays out after a bit of use.

 

For those interested, using my 1.25" diagonal the focuser was racked out to 62mm with my 5mm and 9mm T6 Naglers, about 1mm more with the 24 Pan.  The scope had no clearance issues swinging up to the Zenith at that distance. (Note I do have the extension pier installed).

 

AT92 & AZ-GTi.jpg

 

I only had time for a quick peek at Saturn before being summoned back to work. As Saturn is getting a bit low, over roof tops and only about 20 minutes cooldown, I wasn't expecting much, but focus was sharp with the 5mm (101x). Some bands were apparent on the surface and Cassini was well defined. I didn't get to sweep any star fields with the 24 Pan and can't comment at this time on field curvature. I will add my eyes aren't the best and I don't resolve fine detail as well as a lot of people; it is what it is. Just based on this quick first light peek I know I'm going to get plenty of enjoyment from the AT92.


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#1167 Tyson M

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Posted 13 November 2019 - 11:43 PM

20191113_195931.jpg

 

I had average seeing, but poor transparency with a near full moon. I decided to take out the AT92 again in my backyard red/white zone.

 

I really wanted to test the ES 17mm 92 deg.  Overall it is just an epic eyepiece.  I do not use that word often, but it is truly epic in every way.  

In my AT92 f5.5 it sings.  Perfectly corrected with huge swaths of sky that it swallows up, and it actually is fairly good on the 98.1% full moon.

I had a look at M27, no visible with the light pollution and moon, but with the UHC and OIII filter it was visible.  I found M57 as well without the filter but super faint.

I had a look at Vega and star field.  I had a look at Altair and surrounding starfields. I swalled up the double cluster, which look muted being so close to the bright moon but still noticeable. 

 

Also Melotte 20, which was perfectly corrected but a bit cut off from being able to view it in its entirety.  I had a look at M36, M37, M38....I believe I could only see M36 but I wasnt scrutinizing in this area with how much light was being reflected from the moon. 

 

I had a look at M45, which was super close to the moon but still a nice view.

 

The moon was actually quite good in the ES 17 as well.  Normally wide field eyepieces do not do too well but I was impressed TBH.

Not quite as the clarity of the Brandons, but that could have been an exit pupil thing, as the moon can be fickle that way.  You really need to match exit pupils exactly otherwise it is very difficult to discern differences.

Larger exit pupil especially typically pops more, looks better than a smaller exit pupil IME.

Colors seem to pop like nothing else on the moon with those Brandons, especially tonight in average seeing.  The full moon was looking stunning with all eyepieces tonight, up until a 32 brandon and 5x powermate which the seeing started getting a tiny bit wavy.  The 15 and 11 delites were performing very well.  I alternated between the lumicon 25% neutral density filter, the lumicon light yellow, and lumicon orange filter while viewing the moon, each with their roles to play on viewing luna. 

Another awesome part of the night was the clouds that transited the disk.  I took off all filters when this did that and the light, thin cloud did little to hamper the view, actually made it a bit contrasty.  

 

I spent most of my time on the terminator, if you can call it that with such a bright illumination phase.  Key aspects were observing Pentavius, including its central peaks and Rimae Petavius visible inside it. Also 

There was a mare on the edge of visibility, Vendelinus which looked great. Mare Crisium also dominated the view, with its smooth flooded lava plane.  Small craters were visible on the surface at the edge of visibility on Mare Crisium's floor, and the geological folds were also noted in the large mare.

Other medium sized craters like Wrottesley, Pentavius B, Lohse, and a trio of small craters around Langrenus, which that in itself was the next most attractive large crater with its central peaks, rivalling Pentavius with its grandeur. 

 

I was worried a fast scope might not ever give me jaw dropping views of the moon, nothing like longer focal length scopes can deliver but tonight just proved otherwise, that fast quality scopes can rise to the occasion. Finding focus is a tad harder than it would be on a f7.5+ refractor, but the fine focuser on the AT92 is very easy to dial in smoothly.  It is also comes to a sharp focus, where you know you are in hard focus. 

This fact is especially true with viewing double stars.  I tested it out on Almach tonight.  Brilliant orange/yellow and blue secondary always deserves a look.  I checked it out with the 24 brandon and 5 x powermate, and got the air disk of the main component of Almach.

 

The night wasn't conducive to viewing much other than the moon, but it was a fun night out nonetheless. 

 

Thanks for reading and clear skies! 


Edited by Tyson M, 14 November 2019 - 12:07 AM.

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#1168 scooke

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Posted 13 November 2019 - 11:50 PM

Found it!  It's mentioned in post #1135 by scooke on page 46:  https://www.cloudynighe That is correct.  The TSFlat2 works great for visual and the Stellarvue 2.5" flattener works great for photography


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#1169 Digipainter

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Posted 16 November 2019 - 03:19 PM

Here's an image from last night. I used the AT92, AT2FF and the asi1600mm-Pro. Loving the AT92

IC1396 111519

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#1170 ken30809

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Posted 16 November 2019 - 08:37 PM

Beautiful image!!


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#1171 elmiko

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Posted 16 November 2019 - 09:21 PM

Excellent image Tim! It's been a while since I have seen a post from you! I'm glad you are loving the scope!


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#1172 Digipainter

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Posted 16 November 2019 - 10:30 PM

Excellent image Tim! It's been a while since I have seen a post from you! I'm glad you are loving the scope!

Just enjoying life, being laid back and having some fun DSO imaging . . .  it's fun when it all works, the clouds are sort of staying away . . . but  . . . "Winter's Coming"  . . . I'm still following the thread, watching what peeps are doing with the AT92 . . .  Some are successful with their endeavors and some are not.  Fair skies Mike . . . 


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#1173 10gauge

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Posted 17 November 2019 - 12:48 PM

So, will there be a dedicated flattener that will thread into the focuser in the next 3 months? In the meantime, do we use a 1.0X flattener or 0.75X reducer with the AT92? What’s the optical chain?

 

Opinions vary for imaging. In an earlier thread (#944), I see vignetting with a M42 diameter tube. Perhaps a M48 would be better in regard to vignetting. Decentering was also noted on the diagonal coupler end with a camera. So a threaded solution for a flattener may be ideal with the extra camera weight.

 

I was thinking about implementing the TSFlat2.5. Has anyone done this?...
The AT92 and TS 90 scopes have M63x1 female threads on the EP side of the focuser. The TSFlat2.5 has a M63x1 female thread on the focuser end, so M63 male to M63 male Adapter is needed. The camera end of the TSFlat2.5 is M69x1. So, a M69x1 to M48x1 adapter is needed. The flange distance of Nikon F mount is 46.5mm. The TSFlat2.5 requires 106mm back focus distance for a <500mm scope, and 101mm for a 510-600mm scope.

 

I’m trying to decide on a 90mm class APO refractor. I already have a TEC 140 for visual and dedicated FF, but can’t remember the last time I used it. It’s too big to transport 80mi and set up. I like the fact that the AT92 is much shorter than the TS 90, but the flattener issue seems untested to this point.


Edited by 10gauge, 17 November 2019 - 12:49 PM.


#1174 Tyson M

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Posted 23 November 2019 - 01:10 PM

Tyson, thank you very much for your review. Your opinion is very valuable to me, since I've been looking for a new travel scope since May, and the AT92 is a strong contender (another contender is the TS90; it's slightly longer than the AT92 at 500 mm, but it comes with a splittable tube). Looking forward to your new observation reports with the AT92. Is there any chance for you to do observations using eyepieces from the ES82 line?

 

 

Its hard to say, that TS90 has a few points going for it as well. Looks like a good buy as well.  I havent had that exact scope, but I have experience with TS split tube apos, as I had the 72ED f5.5-  so I will comment on my experiences on that function.

 

The split tube function seems very good on paper, but some minor annoyances flared up while owning one for a while.  The paint seemed to chip and be missing in places around the threaded section, which was noticeable on the OTA once it was completely threaded together.  I was not happy with this when I bought a brand new scope to have paint sections missing, but it appear that more showed up over time.  Also, threaded the scope together in the dark can be risky at times (from cross threading, or dropping, ect).

You will also need to get lens coat hoodies to put on the section that has the lenses, as dust gets on the inside glass as it would be open to the atmosphere when disassembled. My hard fitting cap was also too loose on my TS72apo, so I had to buy another lens coat hoodie for the front of the objective lens side as well.  One could have put more felt inside it, but I was already getting a lens coat for the other side. You can and should carry a bulb blower with you when using any split tube scope.

 

Additionally, more importantly, you may find that one (or more possibly) eyepiece may not achieve focus like the rest of your line up.  This may mean you need to keep threading the section in and taking it out when using that eyepiece. Eyepieces that require more in focus will likely need the threaded section removed.  After a while, I stopped using the eyepiece that was causing me to do this as I didnt want to take off the scope from the mount once I started using it.

 

To speak on your last point, I will not be testing any ES82.  They typically don't have enough eye relief for me with glasses. 

The TS scopes can be very good.  All scopes I owned from them had great optics.  I believe SV imported those scopes for their own so it should  be no surprise many are good to great, with only the rare dud/lemon likely.

 

The TS90 will likely be better on your eyepieces though, at the edges anyways.  But then again I use Brandons on my AT92 (worst case scenario minimum glass)so the edges are noticeable but not too objectionable.  A TV32 plossl would be a better fit than my 32 or 24 Brandon if I was sticking with 1.25" eyepieces only (and still using a 2" diagonal). 

 

I think the build quality would be similar but likely a slight edge to the AT92. Both have nice focusers (that focuser on the TS90 apo is the premium dual speed SV focuser) likely equal in smoothness, but there may be paint specs missing on your threaded parts on the TS, and the AT92 has a twist lock compression fitting which is useful. Also see my comment about the hard lens cover with my TS72.

 

Optically, I think the AT with its minimum 95% strehl standard is a better bet to go. 

For convenience of not having to thread the scope together, again point for AT92.  I see 2.5 to 3 points to the AT92 over the TS's 1 point for being better on eyepiece periphery viewing for a longer focal length.

 

If you can get a 5% CN member discount, even better. 

Hey, just saw an ad for the TS90 apo here on CN.  If you read the seller's assessment, you will find many parallels to what I wrote with my experiences with the split tube 72ED apo.



#1175 t.r.

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Posted 23 November 2019 - 03:24 PM

Jupiter1 I’m real interested in how that mount will perform with the AT 92...keep us posted!


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