Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Reflectors

Pages: 1
Kevdog
Pooh-Bah
*****

Reged: 07/11/12

Loc: Desert Hills, AZ
Paracorr vs ES Coma Corrector new
      #6485346 - 04/24/14 11:11 AM

I know the Paracorr II is THE one to get. But it looks like ES have come out with their own version. http://agenaastro.com/explore-scientific-hr-coma-corrector.html

So is the ES one any good for an f4.5 18" Obsession? What do I get for the extra $150 with the Paracorr? It looks like it is easier to tune.

Plus I was wondering, I have all ES82 eyepieces (30, 18, 11, 7). Would they all use the same setting in the ES, so I wouldn't have to switch anyway. I'm guessing no, since 2 are 2" and 2 are 1.25" and will be in the adapter?

Anyone used both and have any comments/pros/cons?

Thanks!


Post Extras: Print Post   Remind Me!   Notify Moderator  
OrdinaryLight
sage
*****

Reged: 11/06/13

Loc: Massachusetts
Re: Paracorr vs ES Coma Corrector new [Re: Kevdog]
      #6485385 - 04/24/14 11:35 AM

I was tempted by the ES during the recent NEAF sale but some searching revealed that my focuser doesn't have the required 32mm+ of in-focus travel. Your Obsession probably has a fancier focuser than my Chinese Dob so it may not be an issue in your case.

Post Extras: Print Post   Remind Me!   Notify Moderator  
maakhand
professor emeritus
*****

Reged: 09/15/09

Loc: florida, usa
Re: Paracorr vs ES Coma Corrector new [Re: OrdinaryLight]
      #6485431 - 04/24/14 11:50 AM

i think at f/4.5 you should be fine with regular paracorr. usually around 180~200 in used market.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Darren Drake
Carpal Tunnel
*****

Reged: 10/09/02

Loc: Chicagoland
Re: Paracorr vs ES Coma Corrector new [Re: maakhand]
      #6485452 - 04/24/14 11:59 AM

The folks at ES told me at the WSP that this one only has a 1.06X (I think) mag increase instead of the 1.15X from the TV. That alone makes this an interesting item....

Edited by Darren Drake (04/24/14 12:19 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
okieav8rAdministrator
I'd rather be flying!
*****

Reged: 03/01/09

Loc: Oklahoma!
Re: Paracorr vs ES Coma Corrector new [Re: maakhand]
      #6485493 - 04/24/14 12:20 PM

Quote:

i think at f/4.5 you should be fine with regular paracorr. usually around 180~200 in used market.




I agree. Unless one is getting a very fast mirror, the regular Paracorr will work just fine, for a lot less $$$.


Post Extras: Print Post   Remind Me!   Notify Moderator  
George N
Carpal Tunnel
*****

Reged: 05/19/06

Loc: Binghamton & Indian Lake NY
Re: Paracorr vs ES Coma Corrector new [Re: okieav8r]
      #6485553 - 04/24/14 12:54 PM

I would assume that the ES lens is a very good product, just based on their eyepiece efforts. Are they in people’s hands yet?

With the Paracoor II you get published results on how well it corrects coma (better than the original, but the improvement may not be needed) and a tunable top designed to work with Ethos eyepieces (earlier Paracoor won’t), and a lens group designed for removal for use in imaging. Also the machining quality is first rate, with two screws to hold in the eyepiece. The adjustment of the top is very smooth, which is great for actually focusing with it. It is on the heavy side.

At NEAF, TV had a new 3-inch Paracoor, and ES had an 8-inch carbon-fiber tube astrographic Newt with their coma reducer installed in the bottom of the focuser. It was actually a little cheaper than their 6” Mak-Newt.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Paracorr vs ES Coma Corrector new [Re: Kevdog]
      #6486519 - 04/24/14 08:46 PM

The ES might be fine, but if I were buying this item, I would get a Paracorr, a proven performer, with a long track record of success.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Paracorr vs ES Coma Corrector new [Re: Darren Drake]
      #6487359 - 04/25/14 09:13 AM

Quote:

The folks at ES told me at the WSP that this one only has a 1.06X (I think) mag increase instead of the 1.15X from the TV. That alone makes this an interesting item....




and if you look at the chart they're suppose to be good down to the mid 3.whatevers.

and they have a lot more finer focusing helical top, but only a little more smoother.

https://www.youtube.com/watch?v=mLwzqxgbkbI


Post Extras: Print Post   Remind Me!   Notify Moderator  
JimMo
I'd Rather Do It Myself


Reged: 01/08/07

Loc: Under the SE Michigan lightdom...
Re: Paracorr vs ES Coma Corrector new [Re: Pinbout]
      #6487538 - 04/25/14 10:52 AM

Quote:

Quote:

The folks at ES told me at the WSP that this one only has a 1.06X (I think) mag increase instead of the 1.15X from the TV. That alone makes this an interesting item....




and if you look at the chart they're suppose to be good down to the mid 3.whatevers.

and they have a lot more finer focusing helical top, but only a little more smoother.

https://www.youtube.com/watch?v=mLwzqxgbkbI




Is there a quicker way to change settings on the ES? That would be an awful lot of turns to go from say a 21 or 17 Ethos to an 8 or 6 Ethos which have the widest setting difference on a PC2. Sounds like you's need barrel extensions and parfocalizing rings to get them set up so as not to spend the whole evening spinning the "tunable top" to change settings.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Paracorr vs ES Coma Corrector new [Re: JimMo]
      #6487556 - 04/25/14 11:06 AM

Quote:

Is there a quicker way to change settings on the ES?




yeah use a motor.


Post Extras: Print Post   Remind Me!   Notify Moderator  
sixela
Postmaster
*****

Reged: 12/23/04

Loc: Boechout, Belgium
Re: Paracorr vs ES Coma Corrector new [Re: Pinbout]
      #6487700 - 04/25/14 12:18 PM

Use parfocalisation rings. I think a manufacturer of parfocalisation rings bribed ES to design the top this way ;-).

Post Extras: Print Post   Remind Me!   Notify Moderator  
precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: Paracorr vs ES Coma Corrector new [Re: sixela]
      #6487923 - 04/25/14 01:54 PM

Make sure you've got enough in-focus range to use the ES, it requires more than the Paracorr... more than the GSO CC too. It will not work with your typical metal tube Chinese dob, that knocked it out of consideration for me.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Kevdog
Pooh-Bah
*****

Reged: 07/11/12

Loc: Desert Hills, AZ
Re: Paracorr vs ES Coma Corrector new [Re: precaud]
      #6488397 - 04/25/14 05:27 PM

Well, any in-focus will knock it out for me. I'm already at the verge of in-focus problems. In fact I sold my 1.6x 2" barlow as I couldn't focus anything with it. I probably need to shorten the tubes as the JMI focuser the previous owner put on the scope is a bit taller than the original. I just don't have time to mess with it right now!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Scott in NCAdministrator
80mm Refractor Fanatic
*****

Reged: 03/05/05

Loc: NC
Re: Paracorr vs ES Coma Corrector new [Re: Darren Drake]
      #6488452 - 04/25/14 05:52 PM

Quote:

The folks at ES told me at the WSP that this one only has a 1.06X (I think) mag increase instead of the 1.15X from the TV.




This may help to explain the reports that the ES requires a bit more in-focus than the TV.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Paracorr vs ES Coma Corrector new [Re: Scott in NC]
      #6489107 - 04/26/14 01:52 AM

ES in-travel compared to eyepiece with focal plane at shoulder: 32mm.
TV in-travel: 14mm.
I dare say most dobs aren't going to have an extra 32mm of intravel.
Be prepared to cut your poles.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Paracorr vs ES Coma Corrector new [Re: Kevdog]
      #6489112 - 04/26/14 01:55 AM

Quote:

I know the Paracorr II is THE one to get. But it looks like ES have come out with their own version. http://agenaastro.com/explore-scientific-hr-coma-corrector.html

So is the ES one any good for an f4.5 18" Obsession? What do I get for the extra $150 with the Paracorr? It looks like it is easier to tune.

Plus I was wondering, I have all ES82 eyepieces (30, 18, 11, 7). Would they all use the same setting in the ES, so I wouldn't have to switch anyway. I'm guessing no, since 2 are 2" and 2 are 1.25" and will be in the adapter?

Anyone used both and have any comments/pros/cons?

Thanks!



As with the Paracorr, if you find the perfect setting for just one of those, you freeze the focuser and focus using the top of the HRCC. The in-focus setting is the setting for the other eyepiece.
Obviously, this will be easier if your eyepieces are parfocal.
If, like my switch from a 21 Ethos to a 13 Ethos, the difference in setting is 0.7", be prepared for some unscrewing of the top.


Post Extras: Print Post   Remind Me!   Notify Moderator  
jpcannavo
scholastic sledgehammer
*****

Reged: 02/21/05

Loc: Ex NYCer, Now in Denver CO!
Re: Paracorr vs ES Coma Corrector new [Re: Darren Drake]
      #6489202 - 04/26/14 04:44 AM

Quote:

The folks at ES told me at the WSP that this one only has a 1.06X (I think) mag increase instead of the 1.15X from the TV. That alone makes this an interesting item....





Darren

Not sure, but it may be that Paracorr's magnification is the "cost" in their optical design that achieves a negligible introduction (i.e. less than the diffraction limit) of spherical aberration - a nice accomplishment for a paraboloid with a sub aperture coma corrector. Would be curious to know how the ES - with significantly less magnification - fares in this regard.

Joe


Post Extras: Print Post   Remind Me!   Notify Moderator  
sixela
Postmaster
*****

Reged: 12/23/04

Loc: Boechout, Belgium
Re: Paracorr vs ES Coma Corrector new [Re: Starman1]
      #6489215 - 04/26/14 05:22 AM

Quote:

be prepared for some unscrewing of the top.




If you're like me, you'll give up and buy a 2" barrel extender and 2" parfocalisation ring for that 13mm Ethos...


Post Extras: Print Post   Remind Me!   Notify Moderator  
precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: Paracorr vs ES Coma Corrector new [Re: Starman1]
      #6489266 - 04/26/14 07:00 AM

Quote:

ES in-travel compared to eyepiece with focal plane at shoulder: 32mm.
TV in-travel: 14mm.
I dare say most dobs aren't going to have an extra 32mm of intravel.
Be prepared to cut your poles.




I am still amazed that they put that design into production, eliminating, as it does, such a large percentage of the potential user base. Someone at ES didn't have their thinking cap on.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Paracorr vs ES Coma Corrector [Re: precaud]
      #6489370 - 04/26/14 08:47 AM

Quote:

Quote:

ES in-travel compared to eyepiece with focal plane at shoulder: 32mm.
TV in-travel: 14mm.
I dare say most dobs aren't going to have an extra 32mm of intravel.
Be prepared to cut your poles.




I am still amazed that they put that design into production, eliminating, as it does, such a large percentage of the potential user base. Someone at ES didn't have their thinking cap on.




I thought [but never tried] the paracorr II needs 19.5mm of in-travel.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
17 registered and 22 anonymous users are browsing this forum.

Moderator:  ausastronomer, Phillip Creed, JayinUT, okieav8r 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 812

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics