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Visual wide field observation ED80 or AT102ED

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#26 Jon Isaacs

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Posted 17 October 2020 - 09:48 AM

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. 

 

This is Cloudy Nights, hyperbole is not uncommon.  

 

But in more objective terms, like Kev, I had/have what I consider to be a very good 80 mm F/7 William Optics Megrez ll FD. When I bought 15 years ago, it replaced an ED-80 and optically, it was at least the equal of the ED 80.

 

But when acquired my AT-102ED in 2007, it was the same story as Kev's. The 102 mm F/7 provided noticeably more detailed views of Jupiter, Saturn and Mars.  

 

The AT-102ED was not quite as perfect but it definitely showed more.

 

Jon


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#27 YAOG

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Posted 17 October 2020 - 10:11 AM

This is Cloudy Nights, hyperbole is not uncommon.  

 

But in more objective terms, like Kev, I had/have what I consider to be a very good 80 mm F/7 William Optics Megrez ll FD. When I bought 15 years ago, it replaced an ED-80 and optically, it was at least the equal of the ED 80.

 

But when acquired my AT-102ED in 2007, it was the same story as Kev's. The 102 mm F/7 provided noticeably more detailed views of Jupiter, Saturn and Mars.  

 

The AT-102ED was not quite as perfect but it definitely showed more.

 

Jon

And here is the problem, many of the telescopes sold have used the same names and descriptions for totally different scopes. The AT102 you bought was likely the original FPL-53 version which was a lot like the recent Stellarvue FPL-53/equivalent that was dumped as SV exited the imported scope market. That was a much better scope than what is being sold today using the same name and general description of AT102mm f/7 ED.

 

IMO this is deceptive and misleads people into thinking they are buying one thing that got great reviews from well known users like yourself but actually getting a different scope. I do not doubt for a second that your long since discontinued and replaced AT102 f/7 showed more than the ED80 but that scope is not available new today. 

 

I am an AstroTech fan, I've even own one or two bit the current scope is not the same as the one you have/had. This has been an issue for years across many of the imported scope sellers. I wish they would stop doing this and just make up a different name, like AT102 f/7 ED be so we can keep our scope lenses straight. 


Edited by YAOG, 17 October 2020 - 10:39 AM.


#28 KevH

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Posted 17 October 2020 - 10:20 AM

And here is the problem, many of the telescopes sold have used the same names and descriptions for totally different scopes. The AT102 you bought was likely the original FPL-53 version which was a lot like the recent Stellarvue FPL-53/equivalent that was dumped as SV exited the imported scope market. That was a much better scope than what is being sold today using the same name and general description of AT102mm f/7 ED. IMO this is deceptive and misleads people into thinking they are buying one thing that got great reviews from well known users like yourself but actually getting a different scope.

I am an AstroTech fan, I've even own one or two bit the current scope is not the same as the one you have/had. This has been an issue for years across many of the imported scope sellers. I wish they would stop doing this and just make up a different name, like AT102 f/7 ED be so we can keep our scope lenses straight.

The original Kunming United 102EDs were always Fk61/fpl51 based (sold by SV, AT, and Orion). Astronomics even states that the new 102ED is the same as the old one with some optical and mechanical improvements. They clearly state in the description what the ED element is for the current scope as well. Not sure what the issue is here to be honest.

Edited by KevH, 17 October 2020 - 10:31 AM.

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#29 Jon Isaacs

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Posted 17 October 2020 - 10:52 AM

And here is the problem, many of the telescopes sold have used the same names and descriptions for totally different scopes. The AT102 you bought was likely the original FPL-53 version which was a lot like the recent Stellarvue FPL-53/equivalent that was dumped as SV exited the imported scope market. That was a much better scope than what is being sold today using the same name and general description of AT102mm f/7 ED. IMO this is deceptive and misleads people into thinking they are buying one thing that got great reviews from well known users like yourself but actually getting a different scope. I do not doubt for a second that your long since discontinued and replaced AT102 f/7 showed more than the ED80 but that scope is not available new today. 

 

I am an AstroTech fan, I've even own one or two bit the current scope is not the same as the one you have/had. This has been an issue for years across many of the imported scope sellers. I wish they would stop doing this and just make up a different name, like AT102 f/7 ED be so we can keep our scope lenses straight. 

 

:scratchhead:

 

I had the very first AT-102ED. I was given the opportunity to review it because Tom T. was too busy. I ended up buying it.

 

The original AT-102 ED used the same H-FK-61 ED glass that today's AT-102ED uses. The focuser on the current model is much better but otherwise, they seem to be basically the same scope.

 

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

 

Jon


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#30 YAOG

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Posted 17 October 2020 - 11:37 AM

The original Kunming United 102EDs were always Fk61/fpl51 based (sold by SV, AT, and Orion). Astronomics even states that the new 102ED is the same as the old one with some optical and mechanical improvements. They clearly state in the description what the ED element is for the current scope as well. Not sure what the issue is here to be honest.

Oh you mean like this one, the.last generation Access scope? These were released in 2015 and continued to the end in 2020. The previous were straight FPL-53, no lanthanum. 

 

From Stellarvue:

 

Stellarvue's 102 mm Access Refractor presents you with the opportunity to own a high performance Super ED APO at a price that won't break the bank! To keep the cost down while simultaneously maintaining usability, the SV102-ACCESS uses a unique blend of materials. The objective features an apochromatic doublet that uses a Hoya FCD100 glass for maintaining high image contrast, and, because every lens is alignment before it ships, you can be confident that you'll be enjoying color free visual performance minus the higher price. Includes a 2.5" Stellarvue Rack & Pinion focuser that handles any eyepiece/diagonal combination. Furthermore, with this focuser's superior design, smooth yet stable drawtube travel is a guarantee.  



#31 cst4

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Posted 17 October 2020 - 12:06 PM

Stellarvue sold two 102mm F/7 doublet refractors. The older SV102ED had FPL51 glass, same as the AT102ED and Lunt 102ED and other brands. Then there was the SV 102 Access with FPL53 or FCD100 and lanthanum glass, same as the new AT scope coming out and WO sold one like this as well I think. 


Edited by cst4, 17 October 2020 - 12:07 PM.

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#32 KevH

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Posted 17 October 2020 - 12:40 PM

Oh you mean like this one, the.last generation Access scope? These were released in 2015 and continued to the end in 2020. The previous were straight FPL-53, no lanthanum. 

 

From Stellarvue:

 

Stellarvue's 102 mm Access Refractor presents you with the opportunity to own a high performance Super ED APO at a price that won't break the bank! To keep the cost down while simultaneously maintaining usability, the SV102-ACCESS uses a unique blend of materials. The objective features an apochromatic doublet that uses a Hoya FCD100 glass for maintaining high image contrast, and, because every lens is alignment before it ships, you can be confident that you'll be enjoying color free visual performance minus the higher price. Includes a 2.5" Stellarvue Rack & Pinion focuser that handles any eyepiece/diagonal combination. Furthermore, with this focuser's superior design, smooth yet stable drawtube travel is a guarantee.  

Nope.  The original 102EDs were released back in 2008 and were either fk61 or fpl51.  Orion called their version the Orion Premium 102.  Astro-Tech had the AT102ED (just like they do now), and Stellarvue had the SV102ED.  Orion and SV also sold a 110mm version... Also with FK61/fpl51.  Again, these scopes predate the Access line by many years and were NOT fpl53.  

 

To the OP, good luck with your choice. I think both the ED80 and 102ED are capable of providing pleasing wide field and planetary views.  You really can't go wrong with either one.


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#33 Jon Isaacs

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Posted 17 October 2020 - 12:59 PM

Nope.  The original 102EDs were released back in 2008 and were either fk61 or fpl51.  Orion called their version the Orion Premium 102.  Astro-Tech had the AT102ED (just like they do now), and Stellarvue had the SV102ED.  Orion and SV also sold a 110mm version... Also with FK61/fpl51.  Again, these scopes predate the Access line by many years and were NOT fpl53.  

 

To the OP, good luck with your choice. I think both the ED80 and 102ED are capable of providing pleasing wide field and planetary views.  You really can't go wrong with either one.

 

William Optics also sold a version of this scope. It was called the Megrez 102 SV..

 

https://astromart.co...on-megrez-102ed

 

Chip, I don't know how far you go back but these scopes were introduced in 2007-2008 and stayed around a few years.

 

There were no affordable 102mm F/7 FPL-53 doublets. I lobbied Kevin LeGore in this forum to produce an F/7 version of the ED-100 but that never happened. When SV recently came out with the 102 Access, I felt finally someone else recognized this niche but it was short lived.

 

 

Jon


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#34 russell23

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Posted 17 October 2020 - 03:27 PM

And here is the problem, many of the telescopes sold have used the same names and descriptions for totally different scopes. The AT102 you bought was likely the original FPL-53 version which was a lot like the recent Stellarvue FPL-53/equivalent that was dumped as SV exited the imported scope market. That was a much better scope than what is being sold today using the same name and general description of AT102mm f/7 ED.

 

IMO this is deceptive and misleads people into thinking they are buying one thing that got great reviews from well known users like yourself but actually getting a different scope. I do not doubt for a second that your long since discontinued and replaced AT102 f/7 showed more than the ED80 but that scope is not available new today. 

 

I am an AstroTech fan, I've even own one or two bit the current scope is not the same as the one you have/had. This has been an issue for years across many of the imported scope sellers. I wish they would stop doing this and just make up a different name, like AT102 f/7 ED be so we can keep our scope lenses straight. 

I don't think there were any 102mm f/7 using fpl-53 or equivalent before the SV Access - unless maybe Williams optics offered one.

 

Things come and go from the market.  I have both the SV 102 Access and the current generation AT102ED.  Certainly the SV Access has better color correction because of the better ED glass, but the current AT102 is not a step back from those early 102mm f/7's.  Still using the FK-61 glass and the focuser is a significant upgrade from the older models.  

 

And Astrotech is offering a new version using FCD100 glass which should be equivalent to the SV Access.  It is called the AT102EDL. 


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#35 Passerine

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Posted 18 October 2020 - 01:08 PM

arrrrgon:

 

Welcome to Cloudy Nights! 

 

After reading and re-reading what you posted, my 2 cents:  The Orion 80ED is more perfectly suited to your Porta II mount, and is less expensive.  The AT102ED is starting to approach the limit of the Porta II mount, especially at higher magnifications.  You might end up wanting to use a better tripod to make the AT102ED more steady on the Porta II (or maybe not; you may be fine with it...  Do some searching/reading about the Porta II and you'll find lots of opinions).  The AT102ED is certainly more capable.  It has 38% more light gathering and more resolving capability due to the larger objective.  It is not a night and day difference; the 80ED will still present a very enjoyable view, but looking closely it will be noticeable.  For example, open clusters will show a few more faint stars with the 102ED, and as others said above, the moon and planets will show more detail.  Your Zhumell Z8 will be a night and day difference on anything that fits in the field of view, and in that respect, either scope will be a great compliment to the larger scope.  Either scope would be about the same time/trouble to set up in the backyard.  The 80ED might be a little easier to carry out the door on the tripod/mount, "all in one trip," which is important to some folks.  Either scope will give you very enjoyable wide field views.  Finally, if wide field observing is your goal, don't forget you will need a good 2" star diagonal and 2" wide field low power eyepiece in order to get the best wide field views.  Some of the 30-40mm  2" eyepieces are expensive and very heavy.  The APM 30mm ultra flat is well-regarded, not quite as heavy, and a little more affordable.

 

One more thought:  An even smaller scope than the Orion ED80, with a shorter focal length, something like the AT72ED II for example, would also be a lot of fun on the Porta II.  It is back in the more perfect size range for the mount, with even wider possible views (although as the focal length of smaller scopes decreases, field curvature starts to make it more difficult to keep all the stars in focus and sharp out to the very edge of the field).  And a smaller, shorter scope like this would be truly "grab and go" size, very different from the AT102ED.  A better choice for daytime/terrestrial use too.  So in your situation I might go for the AT102ED partly with that in mind (the idea of someday having the option of choosing between 2 more different big/small scopes for the same mount).

 

Good luck!

Dave


Edited by Passerine, 18 October 2020 - 01:34 PM.


#36 kim.davis

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Posted 18 October 2020 - 05:23 PM

Just my thought.

 

I had Skywatcher 80ED which is equivalent to Orion 80ED and now have SV 102 Access which is similar to AT 102ED but with a different glass. Optically my 80ED was very very good for money and aperture. CA is extremely well controlled, I barely noticed CA, I guess part of the reason would be F7.5. Anyway the views were always pleasing, sharp and contrasty. But I didn't like its bulky OTA and mechanics. It's heavy for aperture. I think both tube size would be similar though I didn't measure them side-by-side. 

 

On the other hand, the mechanical quality of SV102A is far better than that of 80ED. Of course I like the optics of SV102A too. I am sure that AT102ED would be mechanically good.

 

If your decision is based on the mount, I don't think there is a huge difference between two as 80ED is bulky (but shorter than AT 102ED when 102ED dew shield is extended, 600mm FL vs 714mm FL). 


Edited by kim.davis, 18 October 2020 - 05:33 PM.


#37 arrrrgon

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Posted 18 October 2020 - 05:35 PM

arrrrgon:

 

Welcome to Cloudy Nights! 

 

After reading and re-reading what you posted, my 2 cents:  The Orion 80ED is more perfectly suited to your Porta II mount, and is less expensive.  The AT102ED is starting to approach the limit of the Porta II mount, especially at higher magnifications.  You might end up wanting to use a better tripod to make the AT102ED more steady on the Porta II (or maybe not; you may be fine with it...  Do some searching/reading about the Porta II and you'll find lots of opinions).  The AT102ED is certainly more capable.  It has 38% more light gathering and more resolving capability due to the larger objective.  It is not a night and day difference; the 80ED will still present a very enjoyable view, but looking closely it will be noticeable.  For example, open clusters will show a few more faint stars with the 102ED, and as others said above, the moon and planets will show more detail.  Your Zhumell Z8 will be a night and day difference on anything that fits in the field of view, and in that respect, either scope will be a great compliment to the larger scope.  Either scope would be about the same time/trouble to set up in the backyard.  The 80ED might be a little easier to carry out the door on the tripod/mount, "all in one trip," which is important to some folks.  Either scope will give you very enjoyable wide field views.  Finally, if wide field observing is your goal, don't forget you will need a good 2" star diagonal and 2" wide field low power eyepiece in order to get the best wide field views.  Some of the 30-40mm  2" eyepieces are expensive and very heavy.  The APM 30mm ultra flat is well-regarded, not quite as heavy, and a little more affordable.

 

One more thought:  An even smaller scope than the Orion ED80, with a shorter focal length, something like the AT72ED II for example, would also be a lot of fun on the Porta II.  It is back in the more perfect size range for the mount, with even wider possible views (although as the focal length of smaller scopes decreases, field curvature starts to make it more difficult to keep all the stars in focus and sharp out to the very edge of the field).  And a smaller, shorter scope like this would be truly "grab and go" size, very different from the AT102ED.  A better choice for daytime/terrestrial use too.  So in your situation I might go for the AT102ED partly with that in mind (the idea of someday having the option of choosing between 2 more different big/small scopes for the same mount).

 

Good luck!

Dave

Thanks for the great info.  I think I'm leaning towards the AT80ED at this point unless there's something between the 80 and 102 that's similar in build quality and price.  I actually have an Orion Q70 that I use for wide field views on my Z8.  It gives fantastic views.

 

Just my thought.

 

I had Skywatcher 80ED which is equivalent to Orion 80ED and now have SV 102 Access which is similar to AT 102ED but with a different glass. Optically my 80ED was very very good for money and aperture. CA is extremely well controlled, I barely noticed CA, I guess part of the reason would be F7.5. Anyway the views were always pleasing, sharp and contrasty. But I didn't like its bulky OTA and mechanics. It's heavy for aperture. I think both tube size would be similar though I didn't measure them side-by-side. 

 

On the other hand, the mechanical quality of SV102A is far better than that of 80ED. Of course I like the optics of SV102A too. I am sure that AT102ED would be mechanically good.

 

If your decision is based on the mount, I don't think there is a huge difference between two as 80ED is bulky (but shorter than AT 102ED when 102ED dew shield is extracted, 600mm FL vs 714mm FL). 

Thanks for the info, and thanks to everyone else who has replied.  This and multiple other threads on CN have been very helpful.


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#38 sanbai

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Posted 18 October 2020 - 10:01 PM

Jumping on Passerine post, and going back to mine:

I flew with my 80ED. For comfort I took a carbon fiber photo tripod (the actual twilight tripod was a no go). It allowed low to mid power, somehow. A heavier OTA (if fitting the cabin baggage) would have been worse. Also, the SkyWatcher focuser was a(nother) PITA with heavy EPs, I'll have to see if I can fix it again...

The optics of the SW are very good (for me), but the tube size and the mechanics are obviously far from optimal. In the long term I'll have to think about it.

The f/7.5 I think it's adequate. It provides still a large field and the field curvature is more controlled than f/6. I don't see it at f/7.5 (that may change with age). It will also be less demanding with eyepieces. But the TV85 gets good reviews anyway, so something to consider.

Edited by sanbai, 18 October 2020 - 10:03 PM.


#39 iKMN

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Posted 19 October 2020 - 10:10 AM

The 4" is going to show a bit more.   I think it really comes down to if you want something that is really quick and ready to go then go with an 80mm.  A 100mm is really not that much harder to bring out but if you think your Z8 is too much for some nights than maybe you should go with a 3" class scope.   From my experience I wouldn't put a 100mm refractor on a Porta II, even with stronger tripod legs.  Of course some people are ok with the stability and use the Porta II with a 100mm refractor but I've been there NOT for me.  Jon brought up a good point and I agree with him.  There will be noticeable field curvature with a low power wide field eyepiece like the Nag 31.  When I had an ED80 both 600FL and 480FL about the best I could do was a 24/82 at F7.5 and 24/68 at F6 for my eyes to accommodate the field curvature.  This will vary between individual.  However, it's not like either scope is unusable with a 31N or wider.  So take my comments as just opinion for "my eyes".  But consider if you want a nice in focus view at the eyepiece with little to no field curvature the FOV is not going to be as big as you can crunch with numbers in theory unless you get a flat field scope like a Petzval or Mak-Newt.   Good luck with a decision.  I am down to 1 scope at the moment myself a dob and am considering a refractor too so I haven't made up my mind either 80 or 100mm - LOL LOL

 

K



#40 arrrrgon

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Posted 19 October 2020 - 11:19 AM

The 4" is going to show a bit more. I think it really comes down to if you want something that is really quick and ready to go then go with an 80mm. A 100mm is really not that much harder to bring out but if you think your Z8 is too much for some nights than maybe you should go with a 3" class scope. From my experience I wouldn't put a 100mm refractor on a Porta II, even with stronger tripod legs. Of course some people are ok with the stability and use the Porta II with a 100mm refractor but I've been there NOT for me. Jon brought up a good point and I agree with him. There will be noticeable field curvature with a low power wide field eyepiece like the Nag 31. When I had an ED80 both 600FL and 480FL about the best I could do was a 24/82 at F7.5 and 24/68 at F6 for my eyes to accommodate the field curvature. This will vary between individual. However, it's not like either scope is unusable with a 31N or wider. So take my comments as just opinion for "my eyes". But consider if you want a nice in focus view at the eyepiece with little to no field curvature the FOV is not going to be as big as you can crunch with numbers in theory unless you get a flat field scope like a Petzval or Mak-Newt. Good luck with a decision. I am down to 1 scope at the moment myself a dob and am considering a refractor too so I haven't made up my mind either 80 or 100mm - LOL LOL

K


I ordered the 80 last night, and I was looking into 2" diagonals, but your post and Jon's post make me wonder if I should just use 1.25" EPs with it.

#41 YAOG

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Posted 19 October 2020 - 11:29 AM

I ordered the 80 last night, and I was looking into 2" diagonals, but your post and Jon's post make me wonder if I should just use 1.25" EPs with it.

With a 1.25" barrel limit you are limited to about a 2.6 degree true FOV. If this is enough FOV and the weight and compact no bulk 1.25" diagonal appeals to you stick with the smaller diagonal. I usually just use a 1.25" diagonal on my 100mm f/9 apo and it works perfectly well for 95% of what I observe. 



#42 arrrrgon

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Posted 19 October 2020 - 12:30 PM

With a 1.25" barrel limit you are limited to about a 2.6 degree true FOV. If this is enough FOV and the weight and compact no bulk 1.25" diagonal appeals to you stick with the smaller diagonal. I usually just use a 1.25" diagonal on my 100mm f/9 apo and it works perfectly well for 95% of what I observe.


Thanks for the info. I'll go with a 2" diagonal then.

#43 iKMN

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Posted 19 October 2020 - 12:31 PM

I ordered the 80 last night, and I was looking into 2" diagonals, but your post and Jon's post make me wonder if I should just use 1.25" EPs with it.

Well field curvature you can focus it out and your eyes (brain) may accommodate it.  If you are younger you might be less susceptible to it.  I am pushing 50 year old eyes (non glasses wearer) and I could pull off a 24mm/82 degree (2" ES) with my 600FL 80ED.  But like I said, it's NOT that the scope is unusable with a 31N or 41P.  If you went with a 480FL 80mm well I had to step down to a 24/68 in 1.25".  Personally, I would go 2" because with either scope there are going to be some huge nebula like the Veil, etc that you want a large exit pupil and filter and you won't be bothered if some of the stars at the edge are out of focus. 

 

I just agree with Jon and wanted to make a point of this too.  Because I made the 'mistake' of thinking I wanted the widest field possible so got an 80mm scope JUST because I thought wow 4-5 degrees FOV - oh boy.  In theory you can get that with the right eyepiece to do that, BUT in reality it's not all in focus - lol.  So if you want a nice in focus wide FOV you wind up using a bit more power anyway reducing the FOV or you pony up $4k for an NP-101is.   However, at least for me and I don't speak for all - I mainly used FLs between around 18-11-7 give or take and then had the 4-5mm for planets and lunar.  Most objects even open clusters are going to fit in the FOV of a 13-10mm.  You will like an ED80 on a Porta II so light and just easy to use.  No excuses to go out and observe unless clouded over. - lol

 

cheers

 

k


Edited by iKMN, 19 October 2020 - 12:32 PM.


#44 gwlee

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Posted 20 October 2020 - 11:57 AM

These small refractors offer more portability than your Z8 and offer wider fields, but in most other respects your z8 offers  far greater optical performance, at least twice the resolution and at least four times the light gathering, so recommend you start by identifying your portability requirements, and then purchase the refractor that comes closest to meeting them. 


Edited by gwlee, 20 October 2020 - 12:42 PM.

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#45 arrrrgon

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Posted 20 October 2020 - 01:08 PM

These small refractors offer more portability than your Z8 and offer wider fields, but in most other respects your z8 offers far greater optical performance, at least twice the resolution and at least four times the light gathering, so recommend you start by identifying your portability requirements, and then purchase the refractor that comes closest to meeting them.


I ordered the AT80ED. It fills a couple of roles that my Z8 doesn't.
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#46 russell23

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Posted 20 October 2020 - 04:09 PM

Well field curvature you can focus it out and your eyes (brain) may accommodate it.  If you are younger you might be less susceptible to it.  I am pushing 50 year old eyes (non glasses wearer) and I could pull off a 24mm/82 degree (2" ES) with my 600FL 80ED.  But like I said, it's NOT that the scope is unusable with a 31N or 41P.  If you went with a 480FL 80mm well I had to step down to a 24/68 in 1.25".  Personally, I would go 2" because with either scope there are going to be some huge nebula like the Veil, etc that you want a large exit pupil and filter and you won't be bothered if some of the stars at the edge are out of focus. 

 

I just agree with Jon and wanted to make a point of this too.  Because I made the 'mistake' of thinking I wanted the widest field possible so got an 80mm scope JUST because I thought wow 4-5 degrees FOV - oh boy.  In theory you can get that with the right eyepiece to do that, BUT in reality it's not all in focus - lol.  So if you want a nice in focus wide FOV you wind up using a bit more power anyway reducing the FOV or you pony up $4k for an NP-101is.   However, at least for me and I don't speak for all - I mainly used FLs between around 18-11-7 give or take and then had the 4-5mm for planets and lunar.  Most objects even open clusters are going to fit in the FOV of a 13-10mm.  You will like an ED80 on a Porta II so light and just easy to use.  No excuses to go out and observe unless clouded over. - lol

 

cheers

 

k

That was pretty much my experience with a Williams Optcs 61mm f/5.9 APO.   I could get around 3.0 deg of sharp FOV.  Eyepieces could provide me more field, but only about the inner 3.0 deg was sharp.  I ended up using the 18.2 DeLite with it because that was sharp to the field stop.



#47 gwlee

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Posted 20 October 2020 - 07:22 PM

I ordered the AT80ED. It fills a couple of roles that my Z8 doesn't.

I think that’s a good choice. An 80mm is lighter scope and requires a lighter mount than the 4-inch you were considering, so it will provide the most portability and FOV, and your Z8 will offer more optical performance when you need it. 


Edited by gwlee, 20 October 2020 - 07:23 PM.

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#48 YAOG

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Posted 20 October 2020 - 07:35 PM

Thanks for the info. I'll go with a 2" diagonal then.

If you are planning to use a 2" diagonal, check the weight as the better made diagonals are heavier and you may want to have a longer dovetail to ensure balancing flexibility. 



#49 russell23

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Posted 20 October 2020 - 08:31 PM

Thanks for the info. I'll go with a 2" diagonal then.

What are you thinking for a 2" widefield eyepiece?  I had the 80mm f/7 SV Access.  The 560mm focal length is fairly forgiving to wide fields, but most low cost wide fields will be a mess over a significant fraction of the field.   As long as you understand that it can be ok.   Also, with a 2" diagonal and eyepiece the back end weight may be quite a bit more than the objective end.    I seem to recall that with my 2" Vernonscope quartz diagonal and a 2" eyepiece the diagonal end would drop when the altitude is not locked.  You'll probably need a long enough dovetail to shift weight forward so that it balances better. 

 

 



#50 arrrrgon

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Posted 20 October 2020 - 10:26 PM

What are you thinking for a 2" widefield eyepiece? I had the 80mm f/7 SV Access. The 560mm focal length is fairly forgiving to wide fields, but most low cost wide fields will be a mess over a significant fraction of the field. As long as you understand that it can be ok. Also, with a 2" diagonal and eyepiece the back end weight may be quite a bit more than the objective end. I seem to recall that with my 2" Vernonscope quartz diagonal and a 2" eyepiece the diagonal end would drop when the altitude is not locked. You'll probably need a long enough dovetail to shift weight forward so that it balances better.


I have a couple I'll try out, but worst case scenario I'll get a 1.25" diagonal if the 2" doesn't work well. I bought the gso 2" dielectric. I have a Q70 which is pretty heavy and the 30mm that came with my Z8. It's not very heavy.

Edited by arrrrgon, 20 October 2020 - 10:31 PM.

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