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ES 24mm 68 vs Agena StarGuider 25mm 60

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#1 KTAZ

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Posted 05 July 2020 - 12:00 PM

I had a chance last night to pop both of these in my SCT and do a quick comparison.

 

I bought the Agena to see if it was truly an upgrade from an old Chinese 26mm plossl. Yes; it is a fine eyepiece for the money ($60). However I wanted to see just what difference I could make out against a higher priced offering.

 

I used the Summer Beehive Cluster as a target. The ES offers a 68 degree field versus the 60 degree of the SG; however, at 24mm the magnification is slightly higher than the AG and the overall impression of the star field is only sightly larger and very similar. I was again impressed by the AG and the clear crisp center view. Both the ES and the SG were pretty much equal here offering crisp pinpoints and views of some very faint stars in the background. Where the AG broke down was the peripheral view. The final 30-40% of the FOV exhibited coma in stars, especially visable when slightly defocused. They were much harder to see at focus, which may be a better measure for the casual observer. The ES bested the AG here with little visable aberrations until the last 10-15% of the field.

 

On Jupiter, I felt the ES provided better contrast and "snap-to" focus than the Agena, but barely. Again, the AG held up nicely for its price point, which is less than half that of the ES when purchased new.

 

How to make a decision between the two? Easy, since the views were marginally better in the ES, you keep that one. BUT, that becomes more difficult when considering comfort and form factor. Something I gave little thought to in the past. Both eyepieces offer long eye relief; but the AG has a nice solid twist-up eyecup versus a simple rubber roll-up on the ES. The ES is also heavier and a little more bulbous in the hand. I found it easier to handle the AG in the dark; and the eyecup, for me, was a clear winner when trying to position your eye away from the lens at the right distance. I wear glasses for distance, but not during observing.

 

What to do? I will wait until I get darker skies to decide. With a full moon I do not feel that I could really do a complete evaluation until I can get some darker backgrounds so I can look at some targets with less skyglow.

 

Thought from other users are welcome! I'd love to hear your experience with either, or both.


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#2 sg6

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Posted 05 July 2020 - 12:28 PM

Thought: At least you do say the ES costs more.

Have seen the Starguiders compared to Delos and the person says they are not as good. However when talking of over a 6x cost difference here, £50 compared to £336 I would seriously hope the Delos was better.

 

The one aspect often said is as you do: The Starguider is a comfortable eyepiece.

In a way the price is comfortable also.


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#3 havasman

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Posted 05 July 2020 - 03:34 PM

Focal ratio of the scope in which the simpler eyepieces are used is critical. They will not match the performance of better corrected eyepieces below @ f6 and at f4.7 and down the performance gaps grows pretty quickly. That correction for faster scopes/steeper light cones is what your $ gets you. Yes, the $60 eyepieces are top bargains especially in their best performance range at f8 and above.


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#4 Jon Isaacs

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Posted 05 July 2020 - 08:23 PM

Focal ratio of the scope in which the simpler eyepieces are used is critical. They will not match the performance of better corrected eyepieces below @ f6 and at f4.7 and down the performance gaps grows pretty quickly. That correction for faster scopes/steeper light cones is what your $ gets you. Yes, the $60 eyepieces are top bargains especially in their best performance range at f8 and above.

 

I have the 25 mm, 18mm, 12mm, 8 mm, 5mm and 3.2 mm Astro-Tech Paradigms, same eyepieces as the Starguiders. 

 

I also have the 16 mm and 24mm Meade SWA's, optically the same as the ES 16 mm and 24 mm 68°.  And there's Naglers, Panoptics and Ethos, what my friend Bob calls my varsity set.

 

My scopes range from F/4.06 to F/7.5 with most being around F/5..

 

Here's the thing: You can't generalize about the Paradigms. The 25 mm does show a good deal of off-axis astigmatism in faster scopes, the 18 mm too. But they're different designs and the 12mm, 8 mm and 5 mm are really quite sharp across the field very different than the 18 mm and 25 mm. I'm talking tight round stars in the NP-101, in my F/4.4 Dobs at F/5.06 with the Paracorr.

 

In the shorter focal lengths, it's easier to manufacture affordable eyepieces that are sharp across the field. They're going to be negative-positive eyepiece's and the negative section gets smaller and smaller with shorter focal lengths.

 

The 25 mm Paradigm is not a negative-positive design....seems like a modified Erfle or something.

 

Jon


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#5 Miranda2525

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Posted 05 July 2020 - 10:31 PM

I had a chance last night to pop both of these in my SCT and do a quick comparison.

 

I bought the Agena to see if it was truly an upgrade from an old Chinese 26mm plossl. Yes; it is a fine eyepiece for the money ($60). However I wanted to see just what difference I could make out against a higher priced offering.

 

I used the Summer Beehive Cluster as a target. The ES offers a 68 degree field versus the 60 degree of the SG; however, at 24mm the magnification is slightly higher than the AG and the overall impression of the star field is only sightly larger and very similar. I was again impressed by the AG and the clear crisp center view. Both the ES and the SG were pretty much equal here offering crisp pinpoints and views of some very faint stars in the background. Where the AG broke down was the peripheral view. The final 30-40% of the FOV exhibited coma in stars, especially visable when slightly defocused. They were much harder to see at focus, which may be a better measure for the casual observer. The ES bested the AG here with little visable aberrations until the last 10-15% of the field.

 

On Jupiter, I felt the ES provided better contrast and "snap-to" focus than the Agena, but barely. Again, the AG held up nicely for its price point, which is less than half that of the ES when purchased new.

 

How to make a decision between the two? Easy, since the views were marginally better in the ES, you keep that one. BUT, that becomes more difficult when considering comfort and form factor. Something I gave little thought to in the past. Both eyepieces offer long eye relief; but the AG has a nice solid twist-up eyecup versus a simple rubber roll-up on the ES. The ES is also heavier and a little more bulbous in the hand. I found it easier to handle the AG in the dark; and the eyecup, for me, was a clear winner when trying to position your eye away from the lens at the right distance. I wear glasses for distance, but not during observing.

 

What to do? I will wait until I get darker skies to decide. With a full moon I do not feel that I could really do a complete evaluation until I can get some darker backgrounds so I can look at some targets with less skyglow.

 

Thought from other users are welcome! I'd love to hear your experience with either, or both.

Get a 25mm Meade HD-60. It's flatter across the field in fast telescopes than the 25mm AT Paradigm or Agena Starguider.



#6 KTAZ

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Posted 05 July 2020 - 11:16 PM

Get a 25mm Meade HD-60. It's flatter across the field in fast telescopes than the 25mm AT Paradigm or Agena Starguider.

I have an f10 which is not considered a fast telescope. Also, I’m not a really a fan of recent Meade products.


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#7 BFaucett

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Posted 05 July 2020 - 11:38 PM

I have the 25 mm, 18mm, 12mm, 8 mm, 5mm and 3.2 mm Astro-Tech Paradigms, same eyepieces as the Starguiders. 

 

I also have the 16 mm and 24mm Meade SWA's, optically the same as the ES 16 mm and 24 mm 68°.  And there's Naglers, Panoptics and Ethos, what my friend Bob calls my varsity set.

 

My scopes range from F/4.06 to F/7.5 with most being around F/5..

 

Here's the thing: You can't generalize about the Paradigms. The 25 mm does show a good deal of off-axis astigmatism in faster scopes, the 18 mm too. But they're different designs and the 12mm, 8 mm and 5 mm are really quite sharp across the field very different than the 18 mm and 25 mm. I'm talking tight round stars in the NP-101, in my F/4.4 Dobs at F/5.06 with the Paracorr.

 

In the shorter focal lengths, it's easier to manufacture affordable eyepieces that are sharp across the field. They're going to be negative-positive eyepiece's and the negative section gets smaller and smaller with shorter focal lengths.

 

The 25 mm Paradigm is not a negative-positive design....seems like a modified Erfle or something.

 

Jon

 

Hey Jon!  wave.gif

 

Jon and I had a nice discussion via PM last May about the Paradigm and Starguider Dual ED eyepieces. Here's a little table that I created for that discussion that I thought I would share here:

 

msg-230527-0-00258800-1590255416.jpg

 

 

Yet, Astronomics describes each eyepiece in their series as:  "The six lens/four group design and two ED (Extra-low Dispersion) glass elements of the [insert focal length here] Astro-Tech Paradigm..."

 

I wonder which specs are correct? Some posters on CN do seem to favor some of the focal lengths in the line/series over other focal lengths. I wonder if the varying number of lens elements and groups might have some bearing on that? I also wonder if Astronomics might have gotten a little carried away with "copy and paste" when writing the lens spec descriptions of each eyepiece on their website. Or, is Agena incorrect with their lens spec descriptions?

 

Just some food for thought...  Cheers! Bob F. smile.gif


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#8 Miranda2525

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Posted 06 July 2020 - 12:19 AM

I have an f10 which is not considered a fast telescope. Also, I’m not a really a fan of recent Meade products.

The 25mm Meade HD 60 will still be better at F/10. I've used it in fast telescopes and slow, and it's a great eyepiece.
I am just trying to help, but you seemed to already have your mind made up.

 

Good luck.


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#9 KTAZ

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Posted 06 July 2020 - 08:28 AM

The 25mm Meade HD 60 will still be better at F/10. I've used it in fast telescopes and slow, and it's a great eyepiece.
I am just trying to help, but you seemed to already have your mind made up.

 

Good luck.

Actually your comment is perfectly valid; didn't mean to come off as closed minded.

 

The Meade might be another potential choice for the budding astronomer that is looking for an alternative to the "stock" eyepiece that shows up in the box with their scope.


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#10 Jon Isaacs

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Posted 06 July 2020 - 09:29 AM

Actually your comment is perfectly valid; didn't mean to come off as closed minded.

 

The Meade might be another potential choice for the budding astronomer that is looking for an alternative to the "stock" eyepiece that shows up in the box with their scope.

 

 

 

I believe the 25 mm Meade 60° is only available used.

 

Jon



#11 Miranda2525

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Posted 06 July 2020 - 11:30 AM

Actually your comment is perfectly valid; didn't mean to come off as closed minded.

 

The Meade might be another potential choice for the budding astronomer that is looking for an alternative to the "stock" eyepiece that shows up in the box with their scope.

The Meade "alternative" is a hecova lot better than a generic eyepiece that shows up in the box with their scopes.



#12 Miranda2525

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Posted 06 July 2020 - 11:31 AM

I believe the 25 mm Meade 60° is only available used.

 

Jon

Which won't be hard to find, if one is patient and waits, plus it's cheap, and very good.



#13 SeattleScott

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Posted 06 July 2020 - 11:46 AM

The Xcel LX 25 is optically the same as the Meade, is currently available and doesn’t say Meade on it (for those who don’t like Meade). This is really the low cost competitor to ES 24/68, APM 24 UFF and 24 Pan. The Paradigm/Starguider 25 is a lower cost alternative more than a lower cost competitor.

Scott
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#14 SeattleScott

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Posted 06 July 2020 - 11:54 AM

Which won't be hard to find, if one is patient and waits, plus it's cheap, and very good.

It’s truly amazing that an eyepiece I purchased new for $70 can be this good. I have no hesitation using it at F4. For $10 more than a Paradigm it was a no-brainer. Granted the line isn’t all this good so paradigms might be as good or better at 12mm or 5mm from what I hear. The paradigm 25 just isn’t as good as most of the others.

Scott
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#15 Supernova74

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Posted 06 July 2020 - 11:58 AM

Amateur Astronomy can be a strange hobby at times useally spending considerable more means better quality in optical performance it doesn’t seem to be always the case in eyepieces.think you have to spend a lot a time at the EP on all various objects to decide.the jump for me was a little easier from Exsplore scientific to Televue as I noticed colour seemed to be more apparent and sharpness towards the very edge FOV also build quality seems second to none.



#16 Starman1

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Posted 06 July 2020 - 12:34 PM

Hey Jon!  attachicon.gifwave.gif

 

Jon and I had a nice discussion via PM last May about the Paradigm and Starguider Dual ED eyepieces. Here's a little table that I created for that discussion that I thought I would share here:

 

msg-230527-0-00258800-1590255416.jpg

 

 

Yet, Astronomics describes each eyepiece in their series as:  "The six lens/four group design and two ED (Extra-low Dispersion) glass elements of the [insert focal length here] Astro-Tech Paradigm..."

 

I wonder which specs are correct? Some posters on CN do seem to favor some of the focal lengths in the line/series over other focal lengths. I wonder if the varying number of lens elements and groups might have some bearing on that? I also wonder if Astronomics might have gotten a little carried away with "copy and paste" when writing the lens spec descriptions of each eyepiece on their website. Or, is Agena incorrect with their lens spec descriptions?

 

Just some food for thought...  Cheers! Bob F. smile.gif

Agena is correct.  Astronomics just cut and pasted from one to the other.


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#17 Starman1

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Posted 06 July 2020 - 12:37 PM

I have the 25 mm, 18mm, 12mm, 8 mm, 5mm and 3.2 mm Astro-Tech Paradigms, same eyepieces as the Starguiders. 

 

The 25 mm Paradigm is not a negative-positive design....seems like a modified Erfle or something.

 

Jon

Jon,

You missed this thread:

https://www.cloudyni...r#entry10294071

It seems the 25mm is a negative-positive design after all.



#18 Jon Isaacs

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Posted 06 July 2020 - 05:12 PM

Jon,

You missed this thread:

https://www.cloudyni...r#entry10294071

It seems the 25mm is a negative-positive design after all.

 

Maybe.. but the field stop/focal plane is before the optics and exactly what role the negative lens plays is not clear.

 

It certainly does not seem to possess the qualities one normally associates with a negative-positive eyepiece.

 

In any event, it's very different in performance and design than others in the Paradigm/Starguider lineup and that's the important point here.

 

It could be what Ernest was talking about recently, a Smyth lens versus a Lens Before Focus.

 

https://www.cloudyni.../#entry10212818

 

"Do not confuse Smyth lens and eyepiece negative lens group before focus (LBF). Smyth lens shall be installed as close as possible to focus with as little as possible influence to focal length, while LBF installed as far as possible from forward focus to influence as much as possible to focal length (eyepiece or objective lens). They work in very different way. LBF is more similar to Barlow (but not identical)..."

 

I think what we call negative-positive is what Ernest calls LBF.

 

Jon


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