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Best planetary EPs being made today...

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#1 jpcannavo

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Posted 28 June 2013 - 05:26 AM

Perhaps relating the market trend towards wide field, "glass heavy" designs, many of the favored high end planetary EPs are no longer being produced (Zeiss, University Optics HDs, Baader GOs, Pentax SMC XOs, etc.). Curious, therefore, to hear opinions are as to best planetary EPs in current production.

Joe

Preemptive post script: Clearly the above question, as I have raised it, is fuzzy. That is, planetary EP optimization varies with variables such as focal ratio of scope, driven vs undriven mount, need for eyeglasses etc. As such, my hope here is to generate discussion, rather than to definitively answer a somewhat vague question.

#2 dweller25

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Posted 28 June 2013 - 05:40 AM

For me it's the Pentax XW series, I have the 7 and 5 and they give me the best planetary views I have ever had.

#3 Mark9473

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Posted 28 June 2013 - 05:42 AM

http://www.universityoptics.com/

#4 John Huntley

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Posted 28 June 2013 - 06:20 AM

The best I've used was a 5mm TMB Supermonocentric. They were out of production for a while but are being produced again now I believe.

The Pentax XW's are superb too with the bonus of comfortable eye relief and a large field of view.

The Baader Genuine Ortho's (replaced by the Astro Hutech orthos now) and the newer Baader Classic Ortho's do really well if you can handle the relatively narrow field of view and limited eye relief.

#5 jpcannavo

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Posted 28 June 2013 - 06:26 AM

John
I have heard this about the XWs over and over again. I since wondered how the TV Delos stack up against them.
Joe

#6 MikeBOKC

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Posted 28 June 2013 - 06:58 AM

For me it's a tie between the XW (7 and 20) and my 16mm Brandons, either mono or binoviewed.

#7 John Huntley

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Posted 28 June 2013 - 07:05 AM

John
I have heard this about the XWs over and over again. I since wondered how the TV Delos stack up against them.
Joe


Joe,

I've not had the pleasure of using a Delos as yet but from all the reports I've read I believe the two types are very, very evenly matched in performance.

#8 BillP

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Posted 28 June 2013 - 07:11 AM

1 - TMB Supermonos. Markus still produces these so technically still in production. However, not all focal lengths available all the time. So sporadic availability.

2 - Brandon. Always a strong performer for planetary. Downside is only short focal lengths are 6mm and 8mm.

3 - Abbe Orthos. Basically, the major quality ones out there...Baader Classic Orthos, new Hutech Orthos, new UO Orthos. While I have not tested the new Hutech and UO, my expectation is that equals to the BGO and old UO HDs that they replaced.

And of course, the many quality premiums do fantastic and only lag very slightly behind the classics - important for the dedicated planetary observer but the difference not always important to others. E.g., XWs, Delos, etc.

#9 csrlice12

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Posted 28 June 2013 - 07:22 AM

7XW, but I must admit, the NLVs are very nice too.

#10 iluxo

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Posted 28 June 2013 - 08:04 AM

For planetary you don't need a sharp field more than a few minutes of arc. Lowest number of air-glass surfaces and/or elements is the way to do this.

#1. natures own eyeball, with the lens removed for a cataract operation. Focus the primary mirror directly on your retina. No eyepiece at all, and no lens in your eye either so that piece of badly corrected biological junk is finally out of the way. Mind-bogglingly good clarity over a small field is the result.

But not for everyone.

#2. Afocal reflector. Just 2 clean mirrors, tiny field of view like a Galilean telescope but achieved with a convex parabolic secondary. I made one, once. Clarity was awesome and on-axis aberrations effectively nil (the scope was effectively f/19).

It's not something anyone would make unless you can do it yourself and tolerate a scope with an apparent field of view around 2 degrees, and an actual field of view in minutes.

#3. Spherical ball. Just two surfaces.

#4. Monocentric, three cemented elements. Steinheil was first, TMB revived the idea.

#5. If anyone made a modern one with coated surfaces, a Ramsden or Huygens. 2 elements, 4 surfaces. but there's no such beastie.

#6. probably a tie between good orthos, Brandons, RKE (3 elements, 4 air-glass surfaces) or Kellner.

#7. The short Vixen LV's, the 7-9mm were indistinguishable from the 8mm RKE IMHO. Any design with around Smythe lens and 5 elements - Masayuma's, Takahashi and the rest.

#8. Widefields. OK, because thats what we all have but not ideal IMHO, far more elements in the way than really necessary, on-axis.

#11 Astrojensen

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Posted 28 June 2013 - 08:15 AM

For planetary you don't need a sharp field more than a few minutes of arc. Lowest number of air-glass surfaces and/or elements is the way to do this.

#1 Spherical ball. Just two surfaces.

#2. Monocentric, three cemented elements. Steinheil was first, TMB revived the idea.

#3. If anyone made a modern one with coated surfaces, a Ramsden or Huygens. 2 elements, 4 surfaces. but there's no such beastie.

#4. probably a tie between good orthos, RKE (3 elements, 4 air-glass surfaces) or Kellner.


You miss a few things:

#1.5: Achromatic cemented doublet. Two lenses, two air/glass surfaces. Available in a large number of focal lengths from Edmund Optics with military-grade scratch-dig ratios.

#3: Zeiss has made coated huygenians of superb quality. They are, however, no better than Kellners or orthos. Super crisp, but suffers from lateral color and ghosting. They do, however correct for false color in long achromats.


Clear skies!
Thomas, Denmark

#12 iluxo

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Posted 28 June 2013 - 08:16 AM

Ah thank you. Just a few off the top of my head, it's late here.

Super crisp, but suffers from lateral color and ghosting. They do, however correct for false color in long achromats.

For years I used to wonder about what would be possible using modern glass types to come up with with a singlet lens (like a solar scope), a secondary lens somewhere halfway (the Dialyte refractor) and a very simple eyepiece specifically designed to match. It would be a single fixed combination but I couldn't help suspecting there are solutions that would easily outperform modern apo's with current eyepieces.

#13 t.r.

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Posted 28 June 2013 - 08:33 AM

Does anyone know what TMB Supermonocentrics are available from Markus currently? I saw an ad a few days ago announcing a new run of focal lengths but it is gone now. I'm thinking I should pick up one pair of these for the binoviewer.

#14 george tatsis

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Posted 28 June 2013 - 08:35 AM

7XW, but I must admit, the NLVs are very nice too.


Being the owner of both, I'll have to agree 100%. ;)

By the way, the NLVs are a bit brighter than the old LV series , which I used to have too.

Still looking for a used NLV 4mm , but I haven't been able to nail one though :(

George

#15 csrlice12

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Posted 28 June 2013 - 08:48 AM

Have the 5,9, and 10 NLV and they're in my case with my Naglers. In my XLT, they see more time then the naglers, love that tracking ability.....

#16 Mark9473

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Posted 28 June 2013 - 09:05 AM

Does anyone know what TMB Supermonocentrics are available from Markus currently?

Their website lists 7, 8, 9, 10 mm.

#17 jpcannavo

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Posted 28 June 2013 - 09:10 AM

For planetary you don't need a sharp field more than a few minutes of arc. Lowest number of air-glass surfaces and/or elements is the way to do this.

#1 Spherical ball. Just two surfaces.


There is an optical question that this design - as in The Siebert Planispheres - has always raised for me. While the advantage of optical simplicity would seem to be maximized in spherical ball lens, how can such a steeply curved singlet avoid on-axis image degradation secondary to both spherical and chromatic aberration?

#18 Jeff Morgan

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Posted 28 June 2013 - 10:55 AM

I've not had the pleasure of using a Delos as yet but from all the reports I've read I believe the two types are very, very evenly matched in performance.


I have run the comparison between the 10 Delos and the 24 Brandon barlowed down to 10 mm. The Brandon was noticeably superior on Saturn and double stars. (See my post from April 18, 2011 number 5179553.)

That being said, the Delos was actually very good in an absolute sense. If you're primarily a DSO person and planets are just a short distraction between observing M7 and M8, the Delos is probably good enough. But if planets are your thing, you can get a quality ortho or Brandon for less money.

Since I ran that head-to-head I have acquired a 14 Delos and 8 Delos (as you can see, I hate them). Over the summer I'll make it a point to run the 8 Delos against the 8 Brandon.

#19 izar187

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Posted 28 June 2013 - 11:15 AM

Perhaps relating the market trend towards wide field, "glass heavy" designs, many of the favored high end planetary EPs are no longer being produced (Zeiss, University Optics HDs, Baader GOs, Pentax SMC XOs, etc.). Curious, therefore, to hear opinions are as to best planetary EPs in current production.

Joe

Preemptive post script: Clearly the above question, as I have raised it, is fuzzy. That is, planetary EP optimization varies with variables such as focal ratio of scope, driven vs undriven mount, need for eyeglasses etc. As such, my hope here is to generate discussion, rather than to definitively answer a somewhat vague question.


I'll put in a vote for Siebert Starsplitters:
http://www.siebertop...rtho page).html

#20 tomharri

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Posted 28 June 2013 - 11:35 AM

Sieberts are junk cause he doesn't have access to hi-quality coatings.

The Pentax XW and Delos are equal to the Zeiss II's on the planets with big eye lens and relief and wide field advantage.

#21 leonard

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Posted 28 June 2013 - 11:40 AM

Hello ,


>>>>>>>> #1.5: Achromatic cemented doublet. Two lenses, two air/glass surfaces. Available in a large number of focal lengths from Edmund Optics with military-grade scratch-dig ratios. <<<<<<<<<

Thomas have you or someone you know tried using these doublets as eyepieces ??? Have been hoping someone would give them a shot but it seems no one has.

Leonard

#22 bremms

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Posted 28 June 2013 - 12:08 PM

TV Plossls are very good. Parks GS-5 7.5mm and 10mm, Zeiss Abbe's, Brandons and various other Orthos. To my eyes the TV Plossls are good as the Brandons and are much better off axis. Had a 10mm edmund triplet in a homemade barrel (machined), but couldn't stand the tiny FOV. Dead on.. it was great. Do have a couple of Radians I use more for planet outreach. They are good, but loose a little contrast to the simple EP's
Still like Orthos, TV Plossls and Brandons. My Parks GS5 7.5mm is very good too.

#23 Astrojensen

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Posted 28 June 2013 - 12:14 PM

Sieberts are junk cause he doesn't have access to hi-quality coatings.



So my prewar 9mm Zeiss ortho is junk, 'cause it has no coatings?


Clear skies!
Thomas, Denmark

#24 bremms

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Posted 28 June 2013 - 12:18 PM

Yea, throw them in the trash. Send it to me, I have some other junk pre war Zeiss stuff.

#25 Astrojensen

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Posted 28 June 2013 - 12:21 PM

Thomas have you or someone you know tried using these doublets as eyepieces ???



Yes. I had an 18mm, with the lens being the achromatic doublet from an old Kellner. It was extremely good on-axis, with super high contrast. It easily outperformed my 18mm UO ortho, especially on objects with very low contrast. It was insanely sharp as well. It was a killer eyepiece for sunspot details.

Somehow, the lens has gotten damaged and has developed a slightly gray surface on one side. Cleaning didn't seem to help. It hadn't cost me anything, so no economic loss, but I sometimes used it for experiments. It had a very narrow field of view, around 12°, but apart from that, it was comfortable to look through. The performance was best when the flattest side of the lens faced the focal plane, showing much less field curvature then.

I've wanted to make a set from Edmund lenses, but I don't have a lathe and many of these lenses are very small, so high precision is needed. My 18mm was only 6mm in diameter.


Clear skies!
Thomas, Denmark






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