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List of Paracorr settings for all brands of EP's

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#176 Michael11

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Posted 17 September 2012 - 11:42 AM

Hello,
I'm using a combination of a universal paracorr (plu-1106) and a tunable top (see attachment). Should I follow the same settings as with type-1 visual?

Another question - can I simply make the distance between eyepiece field lens and the paracorr lens equal to 55mm, or there are other considerations?

thanks in advance.

Attached Files



#177 Starman1

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Posted 17 September 2012 - 01:38 PM

Hello,
I'm using a combination of a universal paracorr (plu-1106) and a tunable top (see attachment). Should I follow the same settings as with type-1 visual?

Another question - can I simply make the distance between eyepiece field lens and the paracorr lens equal to 55mm, or there are other considerations?

thanks in advance.

When the tunable top is added, you essentially have a Paracorr I, so settings will be the same.
The 55mm spacing is between the lens of the Paracorr and the Focal Plane of the eyepiece. That focal plane can be anywhere in the barrel:
in simple eyepieces it's where the iris (knife-edge baffle) is below the bottom lens of the eyepiece. In complex eyepiece designs it can be in-between lenses.

But, as I mentioned, you only have to get one eyepiece right and you can determine the setting for all the others visually and without measurements.

#178 Michael11

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Posted 18 September 2012 - 12:35 PM

Ok, thanks.

#179 csrlice12

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Posted 11 October 2012 - 11:05 AM

Looking at the Televue site, the 13mmT1 (nor any other T1s) are listed. Any ideas why not?

#180 Starman1

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Posted 11 October 2012 - 12:08 PM

Looking at the Televue site, the 13mmT1 (nor any other T1s) are listed. Any ideas why not?

Maybe because they haven't been made since the '80s--since before there was a Paracorr?
It would be easy enough to determine the correct setting, though, using the same technique one uses on a non-TeleVue eyepiece (see previous posts).

#181 Sarkikos

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Posted 12 November 2012 - 08:36 PM

While I was at my dark site this past weekend waiting for the sky to clear, I determined Paracorr Type I settings for a few more eyepieces:

Astro-Tech Titan-II 40mm: Setting 5
Edmund RKE 28.7: Setting 3
Edmund Plossl 28: Setting 3.5
Brandon 12: Setting 4

Mike

#182 Metalmanstan

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Posted 13 November 2012 - 10:02 PM

So may I ask this. I have an orion 12" intelliscope and I have een reading here and there about the paracorr. What is a paracorr? I heard it is not 'needed' but it's good to have for fast scopes. What does it do exactly? Do I need it? It seems very expensive but if I do need it...... I will find a way. If I can't ask it in this thread please delete it and I will make a new one. Thanks!!

#183 Starman1

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Posted 14 November 2012 - 01:48 AM

A Paracorr is a coma corrector made by TeleVue to correct the coma that is a natural by-product of paraboloidal mirrors. Hence, "Para" "Corr".
What is coma?
It is a stretching out of star images along radial lines (from the center out). In the center, there is no stretching, but the farther from center you go, the more stretched the star images.
The stars at the edge begin to resemble comets. Comets is a word from coma in Latin, which means hair. The constellation Coma Berenices means Bernice's hair.
So coma is an aberration that is present in all newtonian images, but which grows worse quickly the shorter the f/ratio of the scope.
No one thinks they need a coma corrector at f/6. By f/5 it's a generous percentage. By f/4.5 at least 50% feel the need, and by f/4 nearly everyone uses a coma corrector.
Your scope is f/5, so it's nice, but not absolutely essential unless you want the star images at the edge of the field to be just as small and sharp as they are in the center. Most people don't expect that, but once you have some experience with a scope where the stars literally are tiny pinpoints from edge to edge in the field, it's kind of hard to go back to having stars in the outer parts of the field look a little flared.

As a matter of exaggeration, the stars in a fast scope look a little like the stars from the flight deck of the Millenium Falcon jumping to lightspeed (in Star Wars) without coma correction, and look like the same field before the jump to lightspeed with coma correction. Of course, it's not that bad, but you get the idea.

Here's a good article to read on the subject:
http://www.astromart...p?article_id=50

#184 SteveG

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Posted 14 November 2012 - 01:13 PM

In short, a Paracorr sharpens up the view in f5 or shorter reflectors. I resisted for years, but finally got one (used) this year. I'm really pleased with the results, even at f5.

#185 Metalmanstan

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Posted 14 November 2012 - 10:19 PM

Does it make it easier to focus the image at high powers or just at any time? and do you need certain eyepieces for it? I had a tough time focusing my 12" f4.9 tonight at about 170x so I was wondering if I needed this? I also started to notice the coma issue tonight. After reading about the paracorr and what it does I started to notice it. I also see that there very expensive.... :-(

#186 Starman1

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Posted 14 November 2012 - 10:48 PM

Does it make it easier to focus the image at high powers or just at any time? And do you need certain eyepieces for it? I had a tough time focusing my 12" f4.9 tonight at about 170x so I was wondering if I needed this? I also started to notice the coma issue tonight. After reading about the Paracorr and what it does I started to notice it. I also see that they're very expensive.... :-(

No, it doesn't change the on-axis images. If you were having trouble focusing, perhaps the seeing conditions just didn't allow that high a power to be used. I've seen nights where 100X was really pushing it on my 12.5", but other nights where 608X was possible.
It's the luck of the draw, assuming your optics are cooled down and your scope is collimated. If it looked good at lower powers, it was probably seeing.

You don't need special eyepieces for a coma corrector.

Yes, they are expensive, but they are on sale right now, so they are a little less expensive. Many people balk at the high price. It's quite understandable.

#187 Doug Culbertson

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Posted 15 November 2012 - 09:15 AM

With an f/4.9, I would just look for a used Type 1 Paracorr rather than spending the princely sum being asked for the Type 2. They can typically be found on the used market for $175-$225.

#188 Sarkikos

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Posted 15 November 2012 - 09:57 AM

With an f/4.9, I would just look for a used Type 1 Paracorr rather than spending the princely sum being asked for the Type 2. They can typically be found on the used market for $175-$225.



That's what I did. In my world, the full price of a new Paracorr Type 2 is out of the question. At f/4.8, my optics don't need correction that badly.

Mike

#189 SteveG

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Posted 15 November 2012 - 12:58 PM

With an f/4.9, I would just look for a used Type 1 Paracorr rather than spending the princely sum being asked for the Type 2. They can typically be found on the used market for $175-$225.



That's what I did. In my world, the full price of a new Paracorr Type 2 is out of the question. At f/4.8, my optics don't need correction that badly.

Mike


As did I - yes the full price is too much! I think I paid $215 for my Type 1, tunable top model. It should be noted that it adds a magnification factor of 1.15x.

#190 ohioalfa64

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Posted 17 December 2012 - 10:43 PM

Sarikakis,
You should publish your findings as a list for Paracorr 1 and Paracorr 2. I own the PC 1 w tunable top. I have a 12.5" dob at f/4.0. With the PC it is 4.6. I was surprised to see that you believe the Nagler 22T4 requires a deeper/lower/closer setting than the ES 20mm 100 deg. I find that surprising. Similarly you find the ES 30mm 82 N2 is easily handled in the PC1, but the Nagler 31mm T5 cannot properly in-focus and must "bottom out" for its improved results--not optimal. Same with Ethos 17 and 21mm. Sounds like you are recommending ES series WFOV eyepieces for budget constrained PC1 owners as they fit. Thanks for the analysis.

#191 gb_astro

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Posted 16 January 2013 - 04:43 AM

So am I right in thinking that Televue is not publishing Delos settings for the Paracorr type I?

gb.

#192 Starman1

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Posted 16 January 2013 - 12:04 PM

So am I right in thinking that Televue is not publishing Delos settings for the Paracorr type I?

gb.

The 12mm and shorter use the same setting as other TeleVue 1.25" eyepieces.
The 17.3 and 14 would use the top turned in all the way and that wouldn't be quite far enough for ideal correction, but it will still be a big improvement.

And, as has been mentioned, if you have even one eyepiece for which a perfect setting has been found or dialed in, you can insert any other eyepiece and focus using the tunable top. When you achieve focus, that setting will be ideal for that eyepiece. Next time, you can pre-set the tunable top to that setting before inserting the eyepiece.

#193 Sarkikos

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Posted 16 January 2013 - 12:53 PM

ohioalfa64,

Sarikakis,
You should publish your findings as a list for Paracorr 1 and Paracorr 2. I own the PC 1 w tunable top. I have a 12.5" dob at f/4.0. With the PC it is 4.6. I was surprised to see that you believe the Nagler 22T4 requires a deeper/lower/closer setting than the ES 20mm 100 deg. I find that surprising. Similarly you find the ES 30mm 82 N2 is easily handled in the PC1, but the Nagler 31mm T5 cannot properly in-focus and must "bottom out" for its improved results--not optimal. Same with Ethos 17 and 21mm. Sounds like you are recommending ES series WFOV eyepieces for budget constrained PC1 owners as they fit. Thanks for the analysis.


This isn't my thread. I've only contributed some of the eyepiece settings. I don't own any Naglers or Ethos, and I don't have an ES 20mm 100, so I can't say anything about those settings.

However, I do recommend ES eyepieces. All of mine have performed well in my Paracorr Type 1. None of my ES have needed more in-focus or out-focus than the Paracorr 1 could provide.

Mike

#194 gb_astro

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Posted 16 January 2013 - 09:56 PM

So am I right in thinking that Televue is not publishing Delos settings for the Paracorr type I?

gb.

The 12mm and shorter use the same setting as other TeleVue 1.25" eyepieces.
The 17.3 and 14 would use the top turned in all the way and that wouldn't be quite far enough for ideal correction, but it will still be a big improvement.

And, as has been mentioned, if you have even one eyepiece for which a perfect setting has been found or dialed in, you can insert any other eyepiece and focus using the tunable top. When you achieve focus, that setting will be ideal for that eyepiece. Next time, you can pre-set the tunable top to that setting before inserting the eyepiece.


Great, thanks,
gb.

#195 photiost

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Posted 01 February 2013 - 09:14 PM

This is a VERY long thread as many people have contributed very useful information on this topic

Just wondering if anyone has been keeping track of the posts and the reported settings for various eyepieces posted here ...
if so, perhaps a table or partial list exists ? :bow:

I did find most of the TV eyepieces with their Paracorr settings posted on their website
.

#196 maire

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Posted 13 May 2013 - 05:51 AM

I can't read all posts... Is there a pdf file for Parracor type 2 settings for other brands? :jump:
Eric

#197 Starman81

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Posted 25 May 2013 - 01:13 AM

This is a VERY long thread as many people have contributed very useful information on this topic

Just wondering if anyone has been keeping track of the posts and the reported settings for various eyepieces posted here ...
if so, perhaps a table or partial list exists ? :bow:

I did find most of the TV eyepieces with their Paracorr settings posted on their website
.


There is a sign in the break room at my workplace which says, "If you see a mess, you own it".

:grin:

#198 Doc Willie

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Posted 30 June 2013 - 10:34 AM

Does it make it easier to focus the image at high powers or just at any time? and do you need certain eyepieces for it? I had a tough time focusing my 12" f4.9 tonight at about 170x so I was wondering if I needed this? I also started to notice the coma issue tonight. After reading about the paracorr and what it does I started to notice it. I also see that there very expensive.... :-(


Actually, I have found the Paracorr useful on occassion for focussing: Often when I am hunting a planetary nebula, and I have a fuzzy object in the center, being able to focus right out the the edge ensures the blurriness is from the object, not my focus.

#199 Sarkikos

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Posted 02 October 2013 - 09:02 AM

I recently upgraded to a Paracorr II. On my last trip to a dark site, I determined a couple settings for the PII.

Leica ASPH: A, and then focus a little in.

LVW 8: A.5 (halfway between A & B)

Mike

#200 Starman81

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Posted 01 December 2013 - 09:17 PM

Anyone input the Delos line into the settings?

All the Delos eyepieces except the 17.3 and 14 will use setting "D" with the Paracorr's supplied 1.25" adapter.
The 17.3 and 14 will require setting "A" for right now, also using the 1.25" adapter.
There may be another, lower-profile, 1.25" adapter for the 17.3 and 14.0 a little later on, as the "perfect" correction for those two will require a setting a little farther in than setting "A".
But "A" will still correct a lot better than no Paracorr, in the same way that the original Paracorr didn't completely correct the 31 Nagler or 21 Ethos but they still were improved a lot over no Paracorr.


Don, will the 17.3/14 Delos only come close to working optimally with the Type 2 ParaCorr? I tried both in my Type 1 (PCV-2000) on setting 1 and the 14 Delos edge performance compared to the XW 14 left much to be desired in the f/4.3 STS 11.






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