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AT80ED vs. AT102ED

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#26 MalVeauX

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Posted 19 September 2021 - 08:46 AM

Heya,

 

The Twilight 1 can handle a lot more with some work. Stock form the Twilight 1 suffers at two main points, the arm (it's hallow and twists and lacks mass) and the primary issue is actually the connection of the mount head to the tripod. This is the weakest point, the tripod connection. Even with everything tight, it has some play to it and this will be realized on any scope you put on it pretty much, even the light weight ones, when you are operating at similar magnifications. If you brace the Twilight 1's arm (cut hard wood block slightly larger than the space in the arm and tap it into place, or brace with aluminum plate on its inside) it will handle things a lot better. And if you replace the tripod connection point with something more sturdy, the head can handle much larger and longer scopes that people would ever imagine. That tripod connection is the weakest point though. Anyhow, there are lots of threads in the Mount forum on this particular mount and how to do these simple fixes to make it a very good little mount.

 

I pier mounted my Twilight 1 head (it connects with 3 bolts instead of 1 center bolt) and braced the arm and it bosses around my 120mm F8 refractor just fine whereas it was literally not usable at all even at low power in its stock form.

 

Looks like you already got an 80mm so that solves that. If you were to re-consider, I would absolutely urge you towards a 102mm. The extra aperture matters a lot on all subjects and a 4" is about the largest (F6~F7) refractor you can go "Grab & Go" with before things get hairy. The classic ED80 refractors are about as big and heavy as a modern 4" refractor is and it's only a 4 inch difference in length.

 

Very best,


Edited by MalVeauX, 19 September 2021 - 08:47 AM.

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#27 Jon Isaacs

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Posted 19 September 2021 - 09:03 AM

For moving around a good bit, and 80 is probably the better choice for most people.

 

While the 100 will show more, it's really a matter of perspective. In the grand scheme of things, and 80 and 100 are more alike than differerent. 

 

I find that my 80mm F6 orion is an easy one hand and out the door set up, whereas my Teleuve 101 is about double the weight, requires a bigger, heavier mount, and is definitely not something that I can move with one hand. I also have a 92, and same deal--it needs a bit more of a mount and tripod, and it's a two-hand move.

 

The TV-101 is longer and heavier than the AT-102ED. 

 

For someone with a single scope, a 4 inch is substantially more capable than an 80 mm.. it captures 64% more light and has 28% better resolution.

 

Ease of use varies with the individual but during the two years I had my AT-102ED, my WO 80 mm F/7 FD just never got used. 

 

Jon


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#28 Echolight

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Posted 19 September 2021 - 09:55 AM

I’m always thinking that I’d like a bigger small scope. But I think that most 4 inch ED scopes kind of cross the line of small to “medium”.
Although many of the f/5 to f/6.5 achromats are lighter and shorter, and should still be steady on the smaller class alt/az mounts. But now you have more chromatic aberration. And potentially lesser grade of focuser and overall build quality, particularly when compared to the AT102ED. But to me, most with a 2 inch focuser would be acceptable for my needs. And I often think the trade off to get the larger aperture between an 80 in ED form to a 100-102 achromat might be worth it.

 

Actually, I most covet a C5 with a reducer for a small scope that would do well on a small mount, in spite of losing maybe a third or so in field of view. Though I figure I’d still be in the 2-2.5 degrees TFOV range. And eventually, maybe an ST80 riding shotgun on a Castor double alt/az mount would more than make up the difference.

 

But to put things in my perspective, in the same price class, relatively, I chose a 6 inch f/8 achromat instead of a 4 inch ED or Apo for my main backyard scope. (It stays stored out there, so I don’t have to carry it through the house). I believe it has shown me many more things than a 4 inch scope in a similar price range would have shown me. And depending on targets, more than the most expensive 4 inch refractors would show. It does require a larger and taller mount though.

 

I don’t in any way think it was a mistake, in spite of seeing countless numbers of optical theories deriding the specs of the scope or comments claiming it as unfit for human eyes. It does a lot better than the numbers would lead you to believe. And much of the specs are irrelevant for deep sky. It does show CA in some cases. But still a ton of detail. More than a typical 4 inch ED I believe. And the aperture and light gathering allow it to go much deeper.

 

The AT80ED is by all accounts a very nice scope though. But for the Twilight I, I might rather carry a 102 f6.5 achromat as my only scope, since I figure the AT102ED might be a little much for the mount. 
 

Of course, opinions will vary. And there are some, that in spite of losing a magnitude or more, and not even accounting for weight, portability, or mounting requirements, would rather use a super high end 70mm refractor than any achromat. No matter how much more they could see in a bigger scope.


Edited by Echolight, 19 September 2021 - 09:57 AM.


#29 areyoukiddingme

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Posted 19 September 2021 - 06:43 PM

The TV-101 is longer and heavier than the AT-102ED. 

 

For someone with a single scope, a 4 inch is substantially more capable than an 80 mm.. it captures 64% more light and has 28% better resolution.

 

Ease of use varies with the individual but during the two years I had my AT-102ED, my WO 80 mm F/7 FD just never got used. 

 

Jon

I also mentioned the Stowaway. The set up with the 80mm Orion is 14lb, the Stowaway 24lb. The difference is quite apparent in weight, but reach is pretty close. If I were carrying a scope after a glass of wine or two, I know which one I should be picking.

 

And note what the OP says (highlight is mine):

 

Seems 80 is a better fit here.

 

Interestingly, the mount discussion is making my decision easier. I'm firmly committed to keeping this a grab & go set-up. I want to be able to carry the whole rig out to my back yard on a cool October night and enjoy a casual tour of the heavens with a glass of wine (or two!).

 

I think the ATED80 on the Twilight sounds like a more manageable set-up. Saves my $200 too which I can spend on more wine!... or EPs. 

 

Hopefully they will get more stock soon!

 

Thanks,

Dave

grabngo.JPG



#30 teashea

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Posted 19 September 2021 - 07:57 PM

The mount is as important as the telescope.  You are walking over the undermount cliff.  


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#31 Jon Isaacs

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Posted 19 September 2021 - 08:17 PM

I also mentioned the Stowaway. The set up with the 80mm Orion is 14lb, the Stowaway 24lb. The difference is quite apparent in weight, but reach is pretty close. If I were carrying a scope after a glass of wine or two, I know which one I should be picking.

 

And note what the OP says (highlight is mine):

 

Seems 80 is a better fit here.

 

attachicon.gifgrabngo.JPG

 

After a glass of wine, it really doesn't matter which scope one chooses..  

 

Jon


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#32 Jon Isaacs

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Posted 19 September 2021 - 08:22 PM

Actually, I most covet a C5 with a reducer for a small scope that would do well on a small mount, in spite of losing maybe a third or so in field of view. Though I figure I’d still be in the 2-2.5 degrees TFOV range. And eventually, maybe an ST80 riding shotgun on a Castor double alt/az mount would more than make up the difference.

 

 

I had a C-5 with a F/6.3 reducer.  With a 32 mm Plossl, the field was seriously vignetted and about 1.85°...

 

An 80 mm F/7 does about 4.7° max, a 102 mm F/7 about 3.7° max.

 

Jon


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#33 areyoukiddingme

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Posted 19 September 2021 - 09:34 PM

After a glass of wine, it really doesn't matter which scope one chooses..  

 

Jon

I can confirm that the less expensive the better.



#34 areyoukiddingme

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Posted 19 September 2021 - 09:42 PM

The mount is as important as the telescope.  You are walking over the undermount cliff.  

I assume you are referring to my picture?

 

The Stowaway is on a Stellarview MC2, rated for up to their 130mm refractors, and the carbon tripod is rated for 88lb. I wouldn't put a 5" scope on this particular tripod, but it's more than enough for the 92mm Stowaway.

 

The Orion is on a Stellarview MV1, probably good for up to 90mm refractors, and my 5lb 80mm is fine. The tripod is rated for 40lb. Again, more than ample.

 

Both are set up for grab and go--the purpose of this thread. If I want more stability, I have much heavier duty tripods. But both are fine going up and over 200x on my balcony with these set ups.



#35 Echolight

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Posted 19 September 2021 - 11:14 PM

I had a C-5 with a F/6.3 reducer.  With a 32 mm Plossl, the field was seriously vignetted and about 1.85°...

 

An 80 mm F/7 does about 4.7° max, a 102 mm F/7 about 3.7° max.

 

Jon

That’s strange. Others have said they used a 27 Pan without issues.

 

I know I tried a 40mm Plossl in my old f/11 C90 yesterday. In the daytime. And while there might’ve been a hint of a shadow at the edge... or I had my eye slightly misaligned, I would not call what I did or didn’t see serious vignetting.
I don’t know what the baffle size is on the C90. Maybe 17mm or 19mm. Considerably less than the 27 and change of the 40 Plossl though. And with a C5 having about a 25-27mm baffle, I figured that it would not be an issue with any 1.25 inch eyepiece.

 

But I haven’t tried a reducer yet. Maybe that changes the dynamic, even though the RC has a 38mm clear aperture.

 

 I’m always miffed by what does and doesn’t show vignetting that some do or don’t find objectionable. I would’ve thought that the XW40 in the C8 would’ve vignetted. I mean a 46.5mm field stop and a 37 or 38mm baffle. But it wasn’t there that I noticed. Or at least the positive greatly outweighed the negative for me.

 

As of yet, the only serious vignetting that I’ve seen has been when I tried the XW40 in my 2 inch Luminos barlow that has a 28mm field stop. I didn’t see it with the 28 PWA and it’s estimated 38-39mm field stop in the same choked down Luminos barlow.

 

I guess with the C5, it’s really the one pound per inch of aperture ratio that is most compelling. Easy to mount. And a very compact 5 inches if space is at a premium.
Other than an ST80 with stock focuser, or a deforked ETX90, you just don’t see that aperture to weight ratio very often.



#36 JRisrad

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Posted 20 September 2021 - 07:42 PM

I think you made a good decision.  I had a TWI and an 80mm scope it was a good combination.  I am getting the AT102EDL hopefully in a few weeks or less but it is going on an M2 mount.  I have a Porta II which is similar to the Twilight I.  I plan on putting an AT72 on it either a new one that I have to order or my friend is going to sell me his.  It will also be a one hand out the door to my back yard.   80mm scopes are nice you will be fine.   Enjoy your new scope when you get it and clear weather too. 

 

cheers

 

K

I’ve been using the Stellarvue M002CS complete mount system (stainless steel tripod) with my AT102EDL. This is the version with the tripod, M2C mount head, and column. I also added the handle. The mount has been very sturdy. I haven’t noticed any vibrations at high power (on doubles or planets). The handle is helpful, and I am already adjusted to not having slow-motion controls. This thing isn’t light with the AT102EDL on it and might not fit everybody’s definition of grab and go. Overall, I’m very happy with this mount and would have no pause recommending it to people with a similarly sized scope.

 

I was previously using a Twilight I. I really liked the Twilight I, but it seemed slightly undersized for the scope. I’m having a little seller’s remorse for not keeping it and adding an AT80ED, but I’ll get over it.


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#37 teashea

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Posted 20 September 2021 - 09:37 PM

After a glass of wine, it really doesn't matter which scope one chooses..  

 

Jon

if it is good wine



#38 duck2k

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Posted 20 September 2021 - 11:39 PM

I too am happy with my AT80 and the Twilight I setup.
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#39 Jon Isaacs

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Posted 22 September 2021 - 09:37 AM

But I haven’t tried a reducer yet. Maybe that changes the dynamic, even though the RC has a 38mm clear aperture.

But I haven’t tried a reducer yet. Maybe that changes the dynamic, even though the RC has a 38mm clear aperture.

 

The reducer changes the dynamic.  If you think of it as reducing the effective focal length of the scope. It also reducers the effective rear port diameter.  The C-5 has a 1 inch = 25.4 mm rear port.

 

With a F/6.3 reducer that becomes 16.0 mm.

 

It's true the reducer has a 38 mm clear aperture but its directly attached to the back of the scope with a 25.4 mm clear aperture which blocks the outer part.

 

Jon



#40 DarkSky64

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Posted 22 September 2021 - 03:21 PM

Received my SW ED80 and ES Twilight mount today. After unpacking and assembling, I'm very impressed. After reading all the complaints about the focuser, I was prepared for the worst, but pleasantly surprised. It's buttery smooth with no slippage. We'll see how it performs under the night sky over time.

 

The Twilight mount seems perfect for this scope. It's beefier than I expected and seems like its' going to be a solid platform for visual use.

 

From a grab-and-go perspective, I'm happy I went with the 80mm. This is still a pretty hefty rig. Definitely not a one-hander.

 

Looking forward to seeing how it performs under the stars. Let's hope the sky clears tonight.

 

In the meantime, here are a couple of pictures.

 

ED80 2.jpg

 

ED80 1.jpg

 

 


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#41 Redbetter

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Posted 22 September 2021 - 06:08 PM

The reducer changes the dynamic.  If you think of it as reducing the effective focal length of the scope. It also reducers the effective rear port diameter.  The C-5 has a 1 inch = 25.4 mm rear port.

 

With a F/6.3 reducer that becomes 16.0 mm.

 

It's true the reducer has a 38 mm clear aperture but its directly attached to the back of the scope with a 25.4 mm clear aperture which blocks the outer part.

FWIW, while it is correct to point out the relative rear port size changes with the reducer (no free lunch), Celestron lists the rear port as 27mm, same as on the C127's and C6's.  That is also the same as the ES 127 and Meade 125. 

 

The ES 127 Mak works with the Celestron .63 reducer and a 24 Pan, even with a 2" SCT diagonal which further reduces focal length with the reducer.  The effective field stop worked out to about 44 mm via drift timing.  It isn't much of a surprise this works, since the same scope could make use of the 46mm field stop of a 55 Plossl with an SCT diagonal--although in that 55 case, additional focal length from the extra diagonal length made this effectively ~42mm at the nominal focal length.

 

Of course, there is always danger in extrapolating, particularly across different types:  in this case projecting from an f/15 Mak to an f/10 SCT.   And the rub with the reducer is when one wants to view at high power, the reducer isn't helping.



#42 Cydonia76

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Posted 23 September 2021 - 04:53 PM

Received my SW ED80 and ES Twilight mount today. After unpacking and assembling, I'm very impressed. After reading all the complaints about the focuser, I was prepared for the worst, but pleasantly surprised. It's buttery smooth with no slippage. We'll see how it performs under the night sky over time.

 

The Twilight mount seems perfect for this scope. It's beefier than I expected and seems like its' going to be a solid platform for visual use.

 

From a grab-and-go perspective, I'm happy I went with the 80mm. This is still a pretty hefty rig. Definitely not a one-hander.

 

Looking forward to seeing how it performs under the stars. Let's hope the sky clears tonight.

 

In the meantime, here are a couple of pictures.

 

attachicon.gifED80 2.jpg

 

attachicon.gifED80 1.jpg

Very nice set up and congratulations on your new scope. I am myself considering this scope for a quick rich field grab and go.

 

when you have a chance I would be really interested to hear your thoughts on it and how much field curvature if any it my have in wider eyepiece

 

there are a few version of these ed80, they have been rock solid performers for decades both for visual and imaging 

 

clear skies




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