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Classic eyepiece comparisonIf I had to rate them

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#1 Richard Whalen

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Posted 01 November 2018 - 09:02 PM

Last night I spent a few hours comparing 3 classic eyepieces.

 

Scope: 6" f12 D&G achromat

 

Eyepieces:

 

15mm TV widefield. 122x

Meade 15.5 RG 118x

Celestron 16mm erfle 114x

 

target was very faint stars in M42, e star in trap, nebulosity and Rigels companion.

 

First off let me say all 3 are fine eyepieces in this scope. At f12, it is quite forgiving. Results may be very different in faster scopes. All 3 eyepieces are based on erfle design.

 

First up was the 15.5 RG. Found the faintest star  I could see see some of the time. Nice wide fov, pretty sharp over the entire fov.

 

Next tried the TV 15mm WF, was suprise at the much smaller fov, about 20% less. Also could only see the faint star maybe 20% of the time. Stars at the edge of the fov seemed bigger, less sharp, And the wings showed a hair less less color and a hair less brightness.

 

Next I tried the Celestron erfle. It was razor sharp in the center of the field of view, the faint star was not as faint and was seen 100% of the time. Had same fov as the TV WF. It equaled the Meade in edge of field sharpness, brightness of wings, though about 20% less fov.

 

I swapped eyepiece around for an hour and came up with same results. Also the Celestron was easier to find best focus, and tied with Meade for comfort. It also was the only one to consistently show the "e" star in the trap, Orion was low and seeing was not great. The TV never showed a hint of it, though the Meade did 50% of the time.

 

Went to Rigel, the Celestron again impressed, gave the best view of the companion with the Meade a very very close second. The TV was a bit further back, not as clean and easy to see.

 

Overall, the Celestron and Meade were very close, the Celestron just edging it out on sharpness and transmission by maybe 1 or 2%, the Meade winning the fov size. The Televue finished 3rd in all respects, but not by much. The Meade is the lightest.

 

If I had to rate them, the Celsetron beinging the baseline 100, the Meade would be 99, and the TV 95. I am going to try them in my F7 apo next, I suspect the TV might do better in it.

 

The old Celestron erfles have always been a favorite of mine for good reason I guess. Star testing them show they have a smooth polish, they don't detract from the scope on axis. Of the three they snap to focus the best, and are comfortable to use to boot. The Meade will remain in my lineup for its wider fov, sharpness and light weight. The TV  is on the fence, depends how it does in my faster refractor.

 

As said, all three eyeices are very good, a casual view would not show any differences except the larger fov of the Meade. Really had to push to see differences. All three are a good value on the used market, most so the Celestron which rarely come up for sale. If you value smaller size over modern super wide eyepices one of them may be for you.

 

 


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#2 jim kuhns

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Posted 01 November 2018 - 09:19 PM

I own a 16mm UO wide field that I have since 1984 and performance is very good.
Mainly use this eyepiece on the planets. Viewing through my Cave 10" F/6 with this
eyepiece at Saturn especially is very enjoyable.
Do you ever use a barlow?
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#3 M11Mike

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Posted 01 November 2018 - 10:18 PM

Maybe that's WHY T/V discontinued the WF's and replaced them with Panoptics???   :-)  

 

I have owned both the 16 and 20mm Celestron Erfles and always like them --- but when I did side by side comparisons about a year ago (similar to yours) against the T/V Panoptic 15 and 19 --- the Pans easily won out.  

 

Center contrast and resolution was about the same --- but the T/V's easily had superior near edge definition and resolution.   And a slightly LARGER FOV to boot.

 

My take here are your key words F12 Achro  & "FORGIVING".  Now - my test was done is a less "forgiving" F10 Celestron SCT.

 

I think for slower scopes (F12 - F15) the Celestron Erfles are great - but in faster scopes (especially F8 and below) you're going to experience issues with them away from center.   Least that has been my experience.  And I too had some longer FL refractors where they worked perfectly. 

 

MP/BL      



#4 bremms

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Posted 02 November 2018 - 10:02 AM

Last night I spent a few hours comparing 3 classic eyepieces.

 

Scope: 6" f12 D&G achromat

 

Eyepieces:

 

15mm TV widefield. 122x

Meade 15.5 RG 118x

Celestron 16mm erfle 114x

 

target was very faint stars in M42, e star in trap, nebulosity and Rigels companion.

 

First off let me say all 3 are fine eyepieces in this scope. At f12, it is quite forgiving. Results may be very different in faster scopes. All 3 eyepieces are based on erfle design.

 

First up was the 15.5 RG. Found the faintest star  I could see see some of the time. Nice wide fov, pretty sharp over the entire fov.

 

Next tried the TV 15mm WF, was suprise at the much smaller fov, about 20% less. Also could only see the faint star maybe 20% of the time. Stars at the edge of the fov seemed bigger, less sharp, And the wings showed a hair less less color and a hair less brightness.

 

Next I tried the Celestron erfle. It was razor sharp in the center of the field of view, the faint star was not as faint and was seen 100% of the time. Had same fov as the TV WF. It equaled the Meade in edge of field sharpness, brightness of wings, though about 20% less fov.

 

I swapped eyepiece around for an hour and came up with same results. Also the Celestron was easier to find best focus, and tied with Meade for comfort. It also was the only one to consistently show the "e" star in the trap, Orion was low and seeing was not great. The TV never showed a hint of it, though the Meade did 50% of the time.

 

Went to Rigel, the Celestron again impressed, gave the best view of the companion with the Meade a very very close second. The TV was a bit further back, not as clean and easy to see.

 

Overall, the Celestron and Meade were very close, the Celestron just edging it out on sharpness and transmission by maybe 1 or 2%, the Meade winning the fov size. The Televue finished 3rd in all respects, but not by much. The Meade is the lightest.

 

If I had to rate them, the Celsetron beinging the baseline 100, the Meade would be 99, and the TV 95. I am going to try them in my F7 apo next, I suspect the TV might do better in it.

 

The old Celestron erfles have always been a favorite of mine for good reason I guess. Star testing them show they have a smooth polish, they don't detract from the scope on axis. Of the three they snap to focus the best, and are comfortable to use to boot. The Meade will remain in my lineup for its wider fov, sharpness and light weight. The TV  is on the fence, depends how it does in my faster refractor.

 

As said, all three eyeices are very good, a casual view would not show any differences except the larger fov of the Meade. Really had to push to see differences. All three are a good value on the used market, most so the Celestron which rarely come up for sale. If you value smaller size over modern super wide eyepices one of them may be for you.

Most of the time Iv'e found the faintest star seen has more to do with seeing, dirty optics and slight focus differences. I have a TV15mm WF and had a 16mm circle T Erfle (same as the Celestron ostensibly).  I found the TV 15 WF much better at EOF, similar at the center and it had less background scatter.(5" F12 D&G and a 10"F6 Newt) It definitely has better coatings than the circle T Erfle. The faint test you are describing shows about 0.5 mag difference. That is a vast difference in transmission ~58%. The TV's coatings have < 0.3% reflection per surface and the circle T Erfle about 1.5%. I'm sure you saw what you saw, but there may have been other factors involved.



#5 Richard Whalen

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Posted 02 November 2018 - 06:53 PM

All eyepieces were clean, coatings like new. Went back and forth over 20 times, so seeing was not an issue. Most of my Celestron erfles are circle V, will have to check what the 16 is. As I said, different scope probably different results. I find many scopes seem to like certain eyepieces better then others, probably why I have so many eyepieces. I was expecting the order to be reversed, was a bit suprised at my results. I did not include a Panoptic as it is a much newer design, not a "classic" eyepiece imho. Plus I really dont care for them, to much distortion when sweeping. They seem to be designed for faster scopes. As many here collect long focal length scopes and vintage eyepieces I kept it to these three I had in my case at the time. Next time I will try in my f7 apo, then maybe my f16 refractor. I use none of these in my 8" f15.5, as the 17mm Nagler seems a perfect mid power eyepiece in that scope.


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#6 Jim Curry

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Posted 02 November 2018 - 10:14 PM

Nice report, thank you.

 

Jim


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#7 rolo

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Posted 02 November 2018 - 10:53 PM

Good job Richard ! I appreciate your time and effort with this reportwaytogo.gif  I've had all three of those eyepieces but never did a side by side.



#8 starman876

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Posted 03 November 2018 - 10:00 AM

Sounds like the Celestron is the sleeper in that bunch.  Great report.  Thanks




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