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Visual wide field observation ED80 or AT102ED

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#1 arrrrgon

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Posted 16 October 2020 - 09:39 AM

I bought a Porta II mount from someone in the classifieds section, and I had myself talked into getting an ED80 for wide field visual use.  Then I saw all of the talk about the AT102ED, and now I'm not sure which one I should grab.  I'll mostly be using it in my back yard, but I would like to be able to carry it other places sometimes too.  I doubt that will be an issue with either of these unless the AT102ED is too heavy for my mount?

 

The 102 should kill the 80 on planets (not really a concern) and DSOs, but does the 80 give a better wide field view?  Has anyone compared the 2 for this situation?  Thanks for any advice guys.

 

I also have a Jason 313 and a Zhumell Z8.  The Z8 is great for everything, but it's also more work to use and just isn't worth it every night.



#2 cst4

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Posted 16 October 2020 - 10:28 AM

I used a 102 ED on a Porta for awhile.  Mine had more solid wooden legs, but it did a fine job carrying that size refractor.  I wouldn't want to go much heavier or longer though.  An ED80 would be very solid I would imagine.  

 

With the right 2" low power eyepiece the 102 ED can easily provide over a 3 degree TFOV.  My 42mm LVW I think is around 3.8 degrees.  This is pretty wide... larger than Andromeda and can fit the entirety of Orion's belt.  I personally don't see much reason to go any wider than that.  If you want wider than that, then I suggest looking into some quality binoculars.

 

The 102ED is a great scope.  There is some CA on bright objects like Jupiter, Venus, and a handful of the brightest stars.  Other than that the image is great and very hard to beat.  I personally would go for a 102 ED over anything 80mm any day.  A 4" refractor can go a lot deeper yet still provide very wide views... very versatile, quite portable, and a whole lot of fun.  

 

Edit:  Thought I would add though that I've never actually owned an 80mm refractor so take my word with a grain of salt.  Maybe I don't know what I am missing.  But in this hobby aperture is king and I can still carry a 4" F/7 on a Porta around the yard in one piece so I have never seen a reason for a smaller scope.  The only reason to go smaller is if you want it to be more stable while in use but one's tolerance for shakes is a personal preference thing.


Edited by cst4, 16 October 2020 - 10:43 AM.

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#3 Alan French

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Posted 16 October 2020 - 10:37 AM

With a 46mm field stop (2-inch eyepiece general maximum) the 80ED (480mm focal length) would provided a 5.5 degree true field. The AT102ED (714mm focal length) would give a 3.7-degree field. 

 

I'd say it's a choice between a wider true field and more portability, and  a more versatile, capable telescope.

 

Clear skies, Alan


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#4 Jon Isaacs

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Posted 16 October 2020 - 10:59 AM

With a 46mm field stop (2-inch eyepiece general maximum) the 80ED (480mm focal length) would provided a 5.5 degree true field. The AT102ED (714mm focal length) would give a 3.7-degree field. 

 

I'd say it's a choice between a wider true field and more portability, and  a more versatile, capable telescope.

 

Clear skies, Alan

 

:waytogo:

 

The ED-80 has a 600 mm focal length which means the maximum field of view is 4.4 degrees.  Of course one could buy an 80 mm F/6..

 

My thinking:

 

I had the very first AT-102ED, that was 2007. At the time, I had my William Optics 80 mm F/7 FPL-53 doublet. I had the AT-102 ED for more than 2 years and during those two years, theb80 mm just sat in its case on the shelf. 

 

I had so much fun with the AT-102ED both in my backyard and under dark skies that I decided to purchase TeleVue 4 inch F/5.4.

 

https://www.cloudyni...h-at102ed-r1690

 

My own thinking is that 3.7 degrees is wide enough.  When you start going to shorter focal lengths field curvature becomes an issue. With my 80 mm F/6, despite a nearly perfect eyepiece like the 31 mm Nagler, the scope's field curvature mean the outer field is not so pretty.

 

I think Alan summed it up and myself, knowing what I know having owned these scopes, I'd go with the AT-102ED.

 

Jon


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#5 c2m2t

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Posted 16 October 2020 - 11:02 AM

Hi Arrrrgon!

I believe you are looking at two very capable telescopes. I am not sure of the manufacturer of the ED80 scope you refer to...there are several brand names with likely most of the optics coming from China. Both scopes are in the F7 to F7.5 range which is a compromise between a better planetary scope vs. a better wide/rich-field scope. Either would make a good grab and go scope but I would suggest the 80mm versions are just a little more transportable. For those of us who have been in the hobby for a while, I think most would agree that a single scope will never fulfill the dedicated observers personal needs. I think 3 is a minimum...one dedicated to widefield for open clusters and brighter DSO's like the Andromeda galaxy and the Orion Nebula, another for planetary/double star work and finally a light bucket to work on the fainter nebulas, galaxies and DSO's.

 

The 80mm ED scopes are very capable and transportable and as you indicate, likely better suited for your mount. I would venture that once you have the 80mm scope, it will be something that will stay with you for a lifetime...it makes a great birding scope, and it is a great entrance scope into astro-photography.

 

I suspect that either scope would be a quick resale if you wanted a change so you can easily change if the urge hits. 

 

I hope that helps.

 

Cheers, Chris.



#6 Alan French

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Posted 16 October 2020 - 11:09 AM

I was thinking ES 80ED f/6 triplet. 

 

Thanks for the correction on the focal length of the ED80 actually being discussed.

 

Clear skies, Alan


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#7 sanbai

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Posted 16 October 2020 - 11:25 AM

A 100 mm unless you want to fly with it and it doesn't fit in a carry-on suitcase. My 80mmED does fit :)

#8 YAOG

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Posted 16 October 2020 - 11:27 AM

I bought a Porta II mount from someone in the classifieds section, and I had myself talked into getting an ED80 for wide field visual use.  Then I saw all of the talk about the AT102ED, and now I'm not sure which one I should grab.  I'll mostly be using it in my back yard, but I would like to be able to carry it other places sometimes too.  I doubt that will be an issue with either of these unless the AT102ED is too heavy for my mount?

 

The 102 should kill the 80 on planets (not really a concern) and DSOs, but does the 80 give a better wide field view?  Has anyone compared the 2 for this situation?  Thanks for any advice guys.

 

I also have a Jason 313 and a Zhumell Z8.  The Z8 is great for everything, but it's also more work to use and just isn't worth it every night.

The AT102 is hardly going to "kill" an ED80 on planets.  The ED80 will offer a slightly wider FOV and will display better CA and possibility SA correction than the AT102. 

 

The AT102 will be able to go a tiny bit deeper but this is really not their best use. The AT102 should be able to cleanly split doubles that are tighter though I doubt you would see much difference without having an excellent top shelf diagonal and eyepieces. 

 

Now if you were to consider the SW, Celestron, Vixen, Orion etc. versions of the ED100 well now you have a scope that will clearly best the ED80. 


Edited by YAOG, 16 October 2020 - 02:04 PM.


#9 SeattleScott

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Posted 16 October 2020 - 12:07 PM

I tend to agree. The 102 will have about 50% more light grasp with 25% more resolution, so maybe something like 40% better views, depending on the target. Certainly a noticeable difference but not a killer difference. Plus the 102 is really pushing it in terms of using the lower grade glass with that much aperture and speed. It just isn’t a planet killer. It might still best an 80ED at F7-7.5 based on aperture alone, but I wouldn’t bet the house on the AT102 vs an FPL53 80mm F7.5 if Jupiter is the target. Mostly you will see the difference on DSO. If you really want a wide field and planetary scope, I would lean towards the 80mm as it will be more portable and better suited for your mount, it can go wider (seems like the wide field junkies say life begins at 4-5 degrees), and it will likely offer similar performance on planets.

Scott
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#10 KevH

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Posted 16 October 2020 - 12:26 PM

The AT102 is hardly going to "kill" an ED80 on planets.  The ED80 will offer slightly wider FOV and will display better CA and possibility SA correction than the AT102. 

 

The AT102 will be able to go a tiny bit deeper but this is really not their best use. The AT102 should be able to cleanly split doubles that a closer though I doubt you would see much difference without having an excellent top shelf diagonal and eyepieces. 

 

Now if you were to consider the SW, Celestron, Vixen, Orion etc. ED100 well now you have a scope that will clearly best the ED80. 

I've compared the AT102ED to a Vixen ED81S.  When the AT102 arrived, my initial comparisons were made during the day in my yard. The little Vixen was clearly superior here as the color correction difference made itself immediately known.  I was going to list the AT102 for sale but thankfully waited until I had a chance to use it at night... as it was intended to be used.  Pointed at the night sky, the added resolution and light grasp of the AT102ED was immediately apparent to my 42 year old eyes. False color was not nearly as noticeable as it had been during my initial daylight tests.    Jupiter wasn't well placed for me at the time but comparing both on high power lunar views, I preferred the 4" to the 3".  The Vixen was still better color corrected but I felt that the AT102ED gave up nothing in the sharpness department.  At 200x on the lunar terminator, there is slight violet fringing on brightly contrasted crater walls with the AT102.  The little Vixen was essentially color free to my eyes at similar mags.  However, the 4" just resolved far more detail and was every bit as sharp.  I LOVED that little Vixen but ended up keeping the AT102ED as it just showed more on every target I looked at. While I didn't get a chance to point both at Jupiter, based on my lunar comparison, I have to believe the larger AT102ED is going to outperform any 3" doublet regardless of how well color corrected it is. Four inches of good shows more than 3 inches of excellent.

 

Additionally, the Vixen ED81S was better than TWO synta 80ED scopes I owned... given how well the AT compared to the Japanese Vixen, I have no doubt it would easily outperform a common synta 80ED on everything. 

 

gallery_108891_302_61748.jpg

 

med_gallery_108891_7937_204319.jpg


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#11 SeattleScott

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Posted 16 October 2020 - 12:30 PM

Consider that the Moon is not a particularly challenging target in terms of CA. I would expect the larger aperture to win out on the Moon, and DSO. Not so sure about Jupiter.

Scott
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#12 KevH

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Posted 16 October 2020 - 12:49 PM

Consider that the Moon is not a particularly challenging target in terms of CA. I would expect the larger aperture to win out on the Moon, and DSO. Not so sure about Jupiter.

Scott

Fair enough.  I have actually used the scope on Jupiter, I just didn't get to side by side it with the smaller 81mm... I don't regret selling the 81mm.  The 102 just shows more even though the color correction isn't as good.  I am extrapolating based on having owned and viewed through both.  Some people are going to extrapolate on specs alone.  The OP is welcome to use whatever info they wish in making their decision. If color correction is the absolute most important criteria, the ED80 is the way to go.  If you want a more capable telescope, I'd go for the 102ED.  


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#13 gnowellsct

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Posted 16 October 2020 - 12:59 PM

 

 

My own thinking is that 3.7 degrees is wide enough.  When you start going to shorter focal lengths field curvature becomes an issue. With my 80 mm F/6, despite a nearly perfect eyepiece like the 31 mm Nagler, the scope's field curvature mean the outer field is not so pretty.

 

I think Alan summed it up and myself, knowing what I know having owned these scopes, I'd go with the AT-102ED.

 

Jon

I'd say 3.7 degrees very likely is enough. And yet you once chided me for never knowing the true joy of wide field viewing because I'm "stuck" with these 4.5 degree 92mm options (Stowaway and CFF).  The gist of the comment was that f/5.5 and a 31mm Nagler was transcendent and f/6.6 and XW40 (4.5 degrees) is mere piker.

 

But perhaps you were annoyed with me that day.  It has been said, that I can be annoying. 

 

Notwithstanding: 3.7 degrees is in the territory of the max FOV of a GT130 (3.4 degrees).  It is to be noted that 3.4 degrees is not really a narrow field view, and that part of these considerations is how much aperture is delivering the field.  A 5 inch 3.4 degree fov is very different from a 3.6 inch 4.5 degree FOV.  

 

Since it is OP's first refractor I would be inclined to recommend the 4 inch so he can see what it is all about.  Plus it puts him squarely into the territory that is covered by Sky Atlas 2000 or Skiff-Tirion's Bright Star Atlas or Sue French's Sampler book and articles.  

 

I thought the f/8.1 Tak FS128 was a very capable "wide field" scope even though its max was 2.7 degrees.  But using an SCT will do that to you: make you think 2.7 degrees is a nice wide field.  The Tak with a 40mm XW offered the same FOV as the GT130 with a 30mm XW.  In terms of my personal viewing habits, f/7 would probably be a better spot for me than f/6.3.  But f/6.3 isn't shabby.

 

Coming back to OP again: I'm not sure why we are worrying about chromatic aberration on the moon or Jupiter.  If it is a good ED it won't have any in focus.  If it's not a good ED, well then, don't get it.   What's the point of paying for color control if you don't get color control.  But it is true that variation among ED options is one of the things to be careful about when buying.

 

Greg N


Edited by gnowellsct, 16 October 2020 - 01:01 PM.

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#14 SeattleScott

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Posted 16 October 2020 - 01:07 PM

Fair enough. I have actually used the scope on Jupiter, I just didn't get to side by side it with the smaller 81mm... I don't regret selling the 81mm. The 102 just shows more even though the color correction isn't as good. I am extrapolating based on having owned and viewed through both. Some people are going to extrapolate on specs alone. The OP is welcome to use whatever info they wish in making their decision. If color correction is the absolute most important criteria, the ED80 is the way to go. If you want a more capable telescope, I'd go for the 102ED.

Spot on.

Of course the other issue is the OP’s mount, and how well it would handle the bigger scope.

Scott
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#15 emilslomi

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Posted 16 October 2020 - 01:07 PM

Reading your "small print" - get the 80. It's a one arm job. 80 and 100 are different, but not THAT much.
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#16 arrrrgon

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Posted 16 October 2020 - 02:47 PM

It's funny, but I never actually mentioned CA in my post.  That part kind of took on a life of it's own.  CA hadn't really crossed my mind with either the AT102ED or the Orion ED80 (which I meant to put in the post, but I forgot the Orion part).

 

I actually do have another refractor.  I have the Jason 313 60mm f/15.  Between it and my Zhumell Z8 the planets are pretty easy targets with no CA.

 

It's a tough call based on what everyone has said, but I definitely want to get a nice refractor.  I just really enjoy the views through a refractor.  

 

I appreciate all the answers and the math lessons everyone :)

 

I'd say 3.7 degrees very likely is enough. And yet you once chided me for never knowing the true joy of wide field viewing because I'm "stuck" with these 4.5 degree 92mm options (Stowaway and CFF).  The gist of the comment was that f/5.5 and a 31mm Nagler was transcendent and f/6.6 and XW40 (4.5 degrees) is mere piker.

 

But perhaps you were annoyed with me that day.  It has been said, that I can be annoying. 

 

Notwithstanding: 3.7 degrees is in the territory of the max FOV of a GT130 (3.4 degrees).  It is to be noted that 3.4 degrees is not really a narrow field view, and that part of these considerations is how much aperture is delivering the field.  A 5 inch 3.4 degree fov is very different from a 3.6 inch 4.5 degree FOV.  

 

Since it is OP's first refractor I would be inclined to recommend the 4 inch so he can see what it is all about.  Plus it puts him squarely into the territory that is covered by Sky Atlas 2000 or Skiff-Tirion's Bright Star Atlas or Sue French's Sampler book and articles.  

 

I thought the f/8.1 Tak FS128 was a very capable "wide field" scope even though its max was 2.7 degrees.  But using an SCT will do that to you: make you think 2.7 degrees is a nice wide field.  The Tak with a 40mm XW offered the same FOV as the GT130 with a 30mm XW.  In terms of my personal viewing habits, f/7 would probably be a better spot for me than f/6.3.  But f/6.3 isn't shabby.

 

Coming back to OP again: I'm not sure why we are worrying about chromatic aberration on the moon or Jupiter.  If it is a good ED it won't have any in focus.  If it's not a good ED, well then, don't get it.   What's the point of paying for color control if you don't get color control.  But it is true that variation among ED options is one of the things to be careful about when buying.

 

Greg N


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#17 clearwaterdave

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Posted 16 October 2020 - 04:13 PM

Hello.,Welcome to CN. You don't need to mention CA. for it to become a problem.,all you need to do is post in the refractor forum. Many here are obsessed with finding it.,Like it's the end all of everything,..lol.,.

 If you want the AT102 you will have to get in line.,or at least wait a bit.,they are lost at sea right now.,.although if you'd settle for the AT80ED.,they got those in stock.,good luck with your choices.,The AT102 is a scope worth waiting for.,imho.,


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#18 YAOG

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Posted 16 October 2020 - 04:25 PM

Optics are compared using objective things like MTF, CA, FC, SA,  distortion etc. What else should we talk about? How pretty it looks on a mount? 


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#19 MalVeauX

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Posted 16 October 2020 - 04:35 PM

Heya,

 

The ED80 is basically a 100mm scope's body with smaller glass in it. It's already the size of a short 4" scope. You would be fine mounting the 102mm F7 ED on your PortaII. It's not a long heavy scope. 600mm vs 700mm is not drastic for FOV. Instead, you get more aperture which goes a lot farther on all subject matter.

 

I'd do the 102mm between the two for visual.

 

Very best,


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#20 Echolight

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Posted 16 October 2020 - 07:07 PM

I think someone here once said that you might as well start with a 4 inch refractor because that's where you'll end up. Now that's probably pretty good advice, but I've been kind of going a long way out of the way to get there. And honestly hope I end up with a short 4.7 apo some day.

 

I bought a little Skywatcher Evostar 80ED recently. I had been wanting one, or some small scope. Although I only got it because I found a great deal on one.

 

I love the wide views. And I have no doubt that the 30 or 40 percent less weight than the 102 will make it more solid on all but the biggest mounts. Mine was shaky on a heavy duty Bogen 3050. But unfazed on a big alt/az mount.

Did someone say they wanted a pretty picture? Over-mounted is nice.

0A62562B-BF24-4EEC-80C6-62801FDE27B8.jpeg

With a 40mm 70 degree eyepiece at 15x everything is plenty bright. 30x with a 20 Hyperwide is bright enough that you can get used to it, although now it's 3.3 degrees instead of 4.5 degrees. And stuff starts getting dark quick when you ramp up the power much more than that.

 

If you're only going to have one refractor though, and you have to pay full price, might as well get a 4 inch. And the AT102 is a little prettier with a better focuser.

 

I'm going to set up my 6 inch tonight. It'll be slightly under mounted on the Unistar. But the ability to go deeper and brighter will be worth it.


Edited by Echolight, 16 October 2020 - 07:12 PM.


#21 clearwaterdave

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Posted 16 October 2020 - 07:53 PM

Optics are compared using objective things like MTF, CA, FC, SA,  distortion etc. What else should we talk about? How pretty it looks on a mount? 

Yes.,And how good the views are.,CA is over rated.,lol.,I don't look at it.,I don't look for it.,I don't see it.,works all good.,And I get to enjoy the great views my achros give.,cheers,.



#22 SeattleScott

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Posted 16 October 2020 - 09:33 PM

Too much is made of CA, this is true, and there is a good reason for that. Because it can be estimated based on specs alone. Without extensive testing by someone knowledgeable and preferably owning lab testing equipment, it can be hard to know SA or astigmatism. But CA is more about glass type, doubly or triplet, or F ratio. So we obsess over what we know rather than speculate about what we don’t know. Ok, let’s be real, speculation goes on too. It’s the refractor forum after all. But yes at times I feel too much is made of CA. CA really is a big deal with a F6 achro. It isn’t as big a deal with an ED scope or F10 achro.

Presumably the 102 would give better views of almost all, if not all targets. The CA would make the improvement less noticeable on bright objects, but realistically the 102 would still have a slight edge. On the other hand the 80mm is smaller, lighter, won’t stress his mount, and is available now. That’s really what it boils down to. How critical is portability to the OP? How sensitive are they to vibrations? That is really what it comes down to. The 102 should provide better views. But is it enough better?

Scott
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#23 jonee523

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Posted 16 October 2020 - 11:44 PM

Hello, I can't really say to much about all the hype about CA. But I can give you an example I recently bought a used SV102 on the CN classifieds. Its the same size physically as the AT102ed as far as I can tell. I have mine mounted on a porta mount tall. Ok here is what I experienced. The mount head itself is ok took about 3-5 seconds to settle down when using higher power eps, in my case a ES 6.5 52*. This was a pain in the ar$e  and somewhat frustrating this was due to the aluminum legs. So my solution was to make a decent set of wooden tripod legs for my porta. My porta now sits at 52" tall fixed, but now my dampen times are under 2 closer to just a second. the actual cost to make the new legs was under $40 and it was money well spent. I in the past had owned a 80mm f/7 ed scope. Its was a great scope for wide views but it was 80mm so pushing past 150x was rough at times. Now on to my current scope SV 102 access, I love the views in my scope period I can push over 200x. I can see more then I remember from my previous 80mm. Planets are brighter and sharper, I can make out more detail say on M31 granted we have all seen it but to see slightly more detail  because of more light collecting glass. M13 goes from a dull blob to a few pin points of light that becomes brighter with averted vision. I guess what I am trying to say is if super portability is not a issue the 102 might offer more in terms of usability. If you would like pics of the tripod mods I made just pm me and I would be happy to share what I learn making them.

 

Clear skies and enjoy,

 

Jon


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#24 makeitso

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Posted 17 October 2020 - 09:13 AM

First off, I have never even looked through an 80mm telescope so I can’t compare. I do have a porta ii and an AT102ED. I can say the AT102ED on the porta is a little shaky at higher powers. If you don’t plan on using it at higher powers on the porta, it makes a great Milky Way sweeper. Maybe I’ll try some wooden legs on it someday.

 

I have a cg4 mount I converted to an az/eq mount, this, with AT102ED is very good. It is heavier though. CA doesn’t get in my way with the AT102ED.

 

To sum it up, for wide field viewing using the porta and the AT102ED, very good! For high power using that combo, a little shaky with the aluminum legs for me.

 

Jack


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#25 russell23

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Posted 17 October 2020 - 09:34 AM

Ultimately, stability is very important to the observing experience.  Based upon my experience using Vixen Superpolaris mounts in alt-azimuth mode, you will need wooden legs for the 4” scope whereas the 80mm scope is very solid on the aluminum legs.  
 

I had an 80mm f/7 SV Access and it was excellent.  It was very solid on my SP mount on aluminum legs whereas the 102mm f/7 has too much vibrations on those legs.  But using the wooden legs the 102mm f/7 is solid. 

 

Dave


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