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Eyepiece Comebacks

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#76 Sarkikos

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Posted 28 October 2013 - 07:36 AM

I concur, Mike. I simultaneously had smoothy and newbie TV Plossls. I kept the newbies. Better edge correction. More neutral tone.

- Jim


The earliest version smoothies had plano eye and field lenses. The TV Plossls with concave outer surfaces have better edge correction. Could your smoothies have been the old plano type? I have a mixed set of TV Plossl smoothies and newbies, from 7.4 to 26mm. All of my TV Plossls have concave eye/field lenses, and they all have very nice edge correction.

I haven't noticed a more neutral tone in my newer TV Plossls. To my eyes, all the TV Plossls I've looked through - smoothie and newbie- have the warm, amber, "coffee" tone. I like that tone for Jupiter belts and lunar maria. I'll have to check out the newer ones to see if the tone is more neutral than the smoothies.

Mike

#77 Jeff Morgan

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Posted 28 October 2013 - 07:50 AM

Jeff,

What's the 19.05mm eyepiece in the pic, a Symmetrical?

Looks like an Edmund.

Thanks,

-Chuck


Yes, it was an Edmund.

#78 leonard

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Posted 28 October 2013 - 11:32 AM

Hello ,

>>>> I'm sorry, but this will not be possible in a 2" barrel. - With 50mm FL Max AFOV will be about 57°. <<<<

Dreaming without knowledge is a wonderful thing as anything is possible !!!

I thank you for pointing this out to me .

Leonard

#79 Chuck Hards

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Posted 28 October 2013 - 12:11 PM

The Pretoria was a great idea and a good eyepiece that went too soon . It never had time to bloom in its own right.



The issue with the Preforia concept is that it only works in Newtonians and you have to buy one for each focal length. Coma correctors are more practical.
Jon


That's exactly the reason I sold my Pretoria some years ago.

Of course, I regret it now. :bawling:

#80 Monoeil

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Posted 28 October 2013 - 12:39 PM

Your Bertele looks like a 30mm to me adapted from a microscope eyepiece.

Years ago, I owned an Intes 18mm Bertele eyepiece and it was pretty awful: strong yellow tone and ghosting. Not worth a cheap Plossl.

Reality can be somewhat different from theory...

#81 bremms

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Posted 28 October 2013 - 12:48 PM

18mm Intes Bertele is a lousy EP. the bright pink coatings look cool.
My vote is for
Zeiss Abbe II
Meade smoothie 5 element super Plossls Those beat the pants off the Celestron sivertops.
Never used a Pretoria, heard good things.

#82 JustaBoy

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Posted 28 October 2013 - 01:16 PM

I think that the biggest problem with Pretoria sales was the 50° AFOV in the time of the 82° Naglers.

I had the U/O 28mm and the Vernonscope 20mm. I thought they did really well, but I have gone to all refractors now, so they went bye-bye.

Damnit! :-(

-Chuck

#83 Jon Isaacs

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Posted 28 October 2013 - 01:22 PM

I think that the biggest problem with Pretoria sales was the 50° AFOV in the time of the 82° Naglers.

I had the U/O 28mm and the Vernonscope 20mm. I thought they did really well, but I have gone to all refractors now, so they went bye-bye.

Damnit! :-(

-Chuck


If I am not mistaken, one of the Pretoria's had a reasonably wide field of view, the other did not.

Jon

#84 JustaBoy

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Posted 28 October 2013 - 01:30 PM

I think that all of them are in accordance with the original design, but I'm wrong about at least something every day:-)

-Chuck

#85 Jeff Morgan

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Posted 28 October 2013 - 02:31 PM

Your Bertele looks like a 30mm to me adapted from a microscope eyepiece.

Years ago, I owned an Intes 18mm Bertele eyepiece and it was pretty awful: strong yellow tone and ghosting. Not worth a cheap Plossl.

Reality can be somewhat different from theory...


It's construction is a little odd, I do not know if it was adapted from a binocular, microscope, or built as a telescope eyepiece. It needs a cleaning so I'll post a few better pics when I take it apart.

It does have nice MgFL coatings (which you may be able to see in that picture), no yellow tone noted. We were looking at open clusters in Cass, no ghosts noted but Jupiter would be a better test. It did notably better than the UO Konigs in Round One, but we only spent about 20 minutes with it - more eyepiece time is needed.

I never expected it to replace my Panoptics, but for the price I could hardly go wrong, even if just to get first-hand experience and satisfy curiosity.

#86 leonard

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Posted 28 October 2013 - 09:01 PM

Hi Jon


The 16mm is said to have 60 deg. AFOV.
How sad that I owned one and cannot remember .


Leonard

#87 leonard

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Posted 28 October 2013 - 11:33 PM

Hello ,


>>>> The issue with the Preforia concept is that it only works in Newtonians and you have to buy one for each focal length. Coma correctors are more practical. <<<<<

The eyepiece was designed to work in fast newtonians so why bring up anything else , so I would not see that as a detrimental.
From what I have read it works just fine in all size newtonian scopes in the F4 to F5 range.
I have no reason to own a Paracorr and do not look forward to owning one . One reason would be weight , I don't like lots of weight at the focuser.
If it were me , using four different FL eyepieces for deep sky , just pop them in and out , no need to adjust anything would be the way to go .
But Pretoria eyepieces never developed pass the first introduction I guess because of the paracorr , which does not mean the paracorr is better or in anyway more practical just that more people went ffor TV eyepieces and the paracorr went with them .
Lets see , 6 elements, great views ,lighter in weight , whats not to like ?????
Take the time to read this eyepiece archive thread by bwilson , called : Pretoria eyepieces pictures , date 10/07 ,everything one would want to know is in the first 3 pages.
Leonard

#88 Starman1

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Posted 29 October 2013 - 01:08 AM

But a coma corrector works with all eyepieces, and parfocalizes them all.
Even if the Pretoria eyepieces still existed, they wouldn't satisfy everyone's taste in eyepieces.
Better to have a coma corrector in the scope, I think, whether attached to the focuser or merely inserted into it.

#89 Jeff Morgan

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Posted 29 October 2013 - 07:10 AM

Yes, a Pretoria would be ideal for a dedicated low-power Milky Way sweeper. Something along the lines of an Astroscan, where a large number of eyepieces would not be used, or even desired.

#90 greju

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Posted 29 October 2013 - 07:53 PM

Would like to see these Kowa's...

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#91 greju

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Posted 29 October 2013 - 07:54 PM

...or any of their derivitives. ;)

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#92 jdbastro

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Posted 29 October 2013 - 11:45 PM

I would like to see a more modern Collins I3 like eyepiece, say in a wide-field or better yet; a zoom!


There is the Micro Monocular which easily adapts for telescope use. It's ocular lens (eyepiece) provides a sharper image across the FOV and a slightly larger apparent FOV vs. the Collins I3.

The Micro is currently shipping.

Here's a pic:

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