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24mm ES 68º in an f/10 SCT Opinions...

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#1 Dave Bush

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Posted 17 August 2014 - 12:50 PM

Looking for opinions on this eyepiece's performance in an SCT at f/10.

 

I've got a Celestron Ultima 24mm and Celestron XCEL-LX 25mm both of which are wonderful but I'm wanting a bit more FOV.

 

I had the ES 82º 24mm but didn't like it.   So I'm curious about the 68º model.

 

Thanks


 

#2 areyoukiddingme

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Posted 17 August 2014 - 12:56 PM

I like it. I bought a pair for binoviewing in my Edge11, but the mono views are very nice too in my c6. I have also used it in my refractors and dobs.

 

They are very sharp too. Compared to my Meade 4000 super plossls, they are actually sharper, which was a surprise. I find the eye relief comfortable (I don't wear glasses), and the fov is nice. It's a bit of a bargain.


 

#3 152ED

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Posted 18 August 2014 - 06:41 PM

Speaking only for my 34mm Meade 5000 swa vs my 30mm uwa in the 12" sct, the 34 is slightly brighter, very sharp on axis and slightly less sharp at the edge than the uwa.  It has great transmission however and not much pincushion, and eye relief is huge compared to the 30.

 

I also have the 24 uwa and it has the most off axis astigmatism of all the s5k uwa's.  Not even close to the 30, 18 & 8.8, which are the best of the set in this regard, IMO.


Edited by 152ED, 18 August 2014 - 06:43 PM.

 

#4 stevew

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Posted 19 August 2014 - 10:59 PM

Looking for opinions on this eyepiece's performance in an SCT at f/10.

 

I've got a Celestron Ultima 24mm and Celestron XCEL-LX 25mm both of which are wonderful but I'm wanting a bit more FOV.

 

I had the ES 82º 24mm but didn't like it.   So I'm curious about the 68º model.

 

Thanks

Just curious about what's not to like about the ES 24MM 82* ?

 

Steve


 

#5 Dave Bush

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Posted 19 August 2014 - 11:08 PM

 

Looking for opinions on this eyepiece's performance in an SCT at f/10.

 

I've got a Celestron Ultima 24mm and Celestron XCEL-LX 25mm both of which are wonderful but I'm wanting a bit more FOV.

 

I had the ES 82º 24mm but didn't like it.   So I'm curious about the 68º model.

 

Thanks

Just curious about what's not to like about the ES 24MM 82* ?

 

Steve

 

Steve, 

 

Before I sold it I had compared it with my Ultima and XCEL-LX and found that it didn't see as deep as those other two.  I could see fainter stars with the others.  Also, sharpness fell off at around 85% of the way to the edge.  That by itself would not necessarily cause me to bail on it but the lack of sharpness and ability to pull out faint stars was significant for me.  Plus it's heavy.

 

Now contrast that with my ES 82º 18mm which is fantastic in all aspects.  Pinpoint, edge to edge.  And it revealed faint stars just as well as my 18mm Ultima and 18mm XCEL-LX.

 

But I would like a wider FOV eyepiece at the 24mm length thus my interest in the ES 68º model.


 

#6 stevew

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Posted 19 August 2014 - 11:40 PM

Dave, thanks for the quick response.

I am surprised at your answer, as I own the ES24 82* as well as the 30mm, and 18mm and I love them all.

My 24 is sharp all the way to the edge even in my 16 inch F-4.5.

Maybe there is some quality variation from eyepiece to eyepiece.

Do you have the newer nitrogen or argon purged or is it one of the older models?

 

Steve


 

#7 Dave Bush

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Posted 19 August 2014 - 11:45 PM

Dave, thanks for the quick response.

I am surprised at your answer, as I own the ES24 82* as well as the 30mm, and 18mm and I love them all.

My 24 is sharp all the way to the edge even in my 16 inch F-4.5.

Maybe there is some quality variation from eyepiece to eyepiece.

Do you have the newer nitrogen or argon purged or is it one of the older models?

 

Steve

Mine was the latest argon purged one.  For some reason, it was the poorest performing of all the ES 82's that I have.  The 18 being the best.  


 

#8 Megabusa

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Posted 21 August 2014 - 12:22 AM

In my 11" Edge My best EPs or my 34MM 68 so far , I just got some new ES EPs but the weather has not been so good here for me to try them out , I'm kinda shocked that you would prefer the 68 over the 82 but , I don't recall looking through a ES 82 24mm EP , but like Steve said , all I hear is very good things about them . :waytogo:


Edited by Megabusa, 21 August 2014 - 12:42 AM.

 

#9 csrlice12

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Posted 21 August 2014 - 08:33 AM

Don't have an SCT, and the ES68 24mm is a nice eyepiece....my ES82 24mm (and 30mm) is one of the original, nonwaterproof versions and looks like a giant tick sucking the photons out of the sky, but the views are great.  M8 in the 24mm is just framed beautifully....heavy bugger though, and possibly too big ergonomically for an SCT....


 

#10 dotnet

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Posted 21 August 2014 - 09:04 AM

looks like a giant tick sucking the photons out of the sky

 

:rofl:


 

#11 aatt

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Posted 21 August 2014 - 09:31 AM

I don't have a SCT, but I so own the 24mm and it really suffers from coma at F/5. At  f/8 is is a very sharp eyepeice to the edge. I have stopped using my 32mm Plossl with my F/8 as the 24mm simply is light years ahead in performance. Although I don't know of any specific optical  issues that go along with SCTs, I imagine that at F/10 you would find the ES 24 to be a very fine performer.


 

#12 Brian Carter

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Posted 21 August 2014 - 09:49 AM

I don't have a SCT, but I so own the 24mm and it really suffers from coma at F/5. At  f/8 is is a very sharp eyepeice to the edge. I have stopped using my 32mm Plossl with my F/8 as the 24mm simply is light years ahead in performance. Although I don't know of any specific optical  issues that go along with SCTs, I imagine that at F/10 you would find the ES 24 to be a very fine performer.

 

 

The 24mm does NOT suffer from coma at F/5, your scope suffers from coma at F/5 and this has nothing to do with the eyepiece.  There's a thread on this recently you should read.  The 24mm may indeed suffer badly at F/5, I don't know.  But IT does NOT suffer from coma.

 

I use the 24ES68 in my C8 and it works great.  I find it very comfortable and just a lovely eyepiece in all possible ways.


 

#13 aatt

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Posted 21 August 2014 - 10:59 AM

O.K. what is the thread then?


 

#14 Brian Carter

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Posted 21 August 2014 - 11:02 AM

http://www.cloudynig...19-mm-panoptic/


 

#15 ChristianG

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Posted 21 August 2014 - 04:34 PM

Looking for opinions on this eyepiece's performance in an SCT at f/10.

 

I've got a Celestron Ultima 24mm and Celestron XCEL-LX 25mm both of which are wonderful but I'm wanting a bit more FOV.

 

I had the ES 82º 24mm but didn't like it.   So I'm curious about the 68º model.

 

Thanks

 

Hi.

 

I had a complete set of Celestron X-Cel LX. I also had an ES68 24 mm which I used with f/12-f/15 Maksutovs. ES68 24 mm is very contrasty, sharp over most of the field of view and very well built. Significantly better than the X-Cel LX in my opinion. Still I sold the ES68 and all the X-Cel LX after a couple months however. Why? In the case of the X-Cel, I was just not happy with kidney beaning and eyeball reflections. In the case of the ES68:

 

--It is a bit bulky--no big deal really.

 

--Rubber eyecup, not twist-up eyecup--again no big deal.

 

--But big deal for me: the 68 degree AFOV is achieved via a good amount of pincushion distortion. The ES68 24 mm has a 27.1 mm field stop, which should give only 59 degrees apparent field of in the absence of geometric distortion. Somehow, absence of pincushion/barrel distortion is important for me, I do terrestrial observing sometimes and that aberration bothers me. The true field of view of the ES68 24 mm is about the same as in a Paradigm 60 degrees 25 mm. Which has comparable sharpness, contrast etc. for half the price and very little geometric distortion.

 

So in the end I got a whole set of Paradigms (Agena Dual ED Starguiders in fact). But that's just me! Have fun shopping.

 

--Christian


 

#16 jeffmac

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Posted 21 August 2014 - 08:24 PM

I don't have a SCT, but I so own the 24mm and it really suffers from coma at F/5. At  f/8 is is a very sharp eyepeice to the edge. I have stopped using my 32mm Plossl with my F/8 as the 24mm simply is light years ahead in performance. Although I don't know of any specific optical  issues that go along with SCTs, I imagine that at F/10 you would find the ES 24 to be a very fine performer.

 
 
The 24mm does NOT suffer from coma at F/5, your scope suffers from coma at F/5 and this has nothing to do with the eyepiece.  There's a thread on this recently you should read.  The 24mm may indeed suffer badly at F/5, I don't know.  But IT does NOT suffer from coma.
 
I use the 24ES68 in my C8 and it works great.  I find it very comfortable and just a lovely eyepiece in all possible ways.


Not sure if this is a dumb question but here goes: If the edges in the ES 24mm 68 look good at f10, how does it look with the reducer at f6.3? The reducer/corrector shortens the focal length but also corrects the field somewhat. So, when will the field look better...at the scope's native f10 or at f6.3?

Regards,

Jeff

Edited by jeffmac, 21 August 2014 - 08:27 PM.

 

#17 ausastronomer

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Posted 21 August 2014 - 08:29 PM

Play nice people

Cheers,
 

#18 Scanning4Comets

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Posted 21 August 2014 - 08:38 PM

The 24mm ES 68 is excellent @ F/10.


Edited by Scanning4Comets, 21 August 2014 - 09:17 PM.

 

#19 Brian Carter

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Posted 21 August 2014 - 08:41 PM

 

 

I don't have a SCT, but I so own the 24mm and it really suffers from coma at F/5. At  f/8 is is a very sharp eyepeice to the edge. I have stopped using my 32mm Plossl with my F/8 as the 24mm simply is light years ahead in performance. Although I don't know of any specific optical  issues that go along with SCTs, I imagine that at F/10 you would find the ES 24 to be a very fine performer.

 
 
The 24mm does NOT suffer from coma at F/5, your scope suffers from coma at F/5 and this has nothing to do with the eyepiece.  There's a thread on this recently you should read.  The 24mm may indeed suffer badly at F/5, I don't know.  But IT does NOT suffer from coma.
 
I use the 24ES68 in my C8 and it works great.  I find it very comfortable and just a lovely eyepiece in all possible ways.

 


Not sure if this is a dumb question but here goes: If the edges in the ES 24mm 68 look good at f10, how does it look with the reducer at f6.3? The reducer/corrector shortens the focal length but also corrects the field somewhat. So, when will the field look better...at the scope's native f10 or at f6.3?

Regards,

Jeff

 

 

 

It it looks better with the reducer.  The SCT field is curved, and although it doesn't bother me too bad with the 24mm, it is noticeable.  With the flattened, it looks just about perfect.  Tiny bit of astigmatism near the edge, but I'd say 95% of the field is very nice.


 

#20 ausastronomer

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Posted 23 August 2014 - 04:56 AM

I have closed this thread as there is another identical thread running

 

 

http://www.cloudynig...s/#entry6175891


 






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