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Equipment Discussions >> Eyepieces

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faackanders2
Carpal Tunnel


Reged: 03/28/11

Re: ES 25mm 100 AFOV Shipped new [Re: smallscopefanLeo]
      #5632535 - 01/20/13 01:09 AM

I could just see it now. Demand for the old eyepieces is less since it comes in the old black box.

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JMW
Pooh-Bah


Reged: 02/11/07

Loc: Nevada
Re: ES 25mm 100 AFOV Shipped new [Re: faackanders2]
      #5641142 - 01/24/13 05:48 PM

I just got back from 4 nights in Death Valley. I was able to observe for 2 nights at Mesquite Springs campground. I did public outreach astronomy for about 30 people the first night and about 15 the 2nd night. There were a lot of scouts and others camping over the 3 day weekend. It was plenty dark for showing the brighter stuff under a 1st quarter moon. The ES25mm 100AFOV eyepiece was used for stuff like M44, M45 and the double cluster. People had no problems with eye placement. After about 3 hours, I set my alarm for 2am and went to bed waiting for the moon to go down.

I spent from 2 to 4 AM enjoying a quite campground with no lights and the moon was down. The 25mm eyepiece was quite useful for scanning the skies. I was using a TEC 140 refractor on a Discmount DM6. It was on a Planet tripod with Losmandy extension. I was able to see Mararian's chain, Leo's triplet and many other galaxies. There was enough of a breeze to chill the air but not enough to bother the scope. The 2nd night I set the alarm for 3am. The wind at that time was too strong so I went back to bed.

I was able to do some back and forth between the ES 25 100 AFOV, the Ethos 21 and Naglar 31T5. There is a lot of overlap between the true field of view of the 31T5 and the ES 25. Both are good eyepieces. If I only used one scope at a time I probably wouldn't own both. Since I am often observing with a 20 inch dob I will keep all of them.

The eyepiece is heavy but it wasn't a problem for my Discmount DM6. I don't think it will mater much on our Obsession 20F5. It may be a problem on an 8-12 inch tube dob.


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Jobryant
sage


Reged: 01/13/09

Re: ES 25mm 100 AFOV Shipped new [Re: JMW]
      #5641761 - 01/25/13 12:01 AM

Good report Jeff! So if you happen to only use one scope at a time what EP would you choice to own the 31T5 or the ES 25?

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JMW
Pooh-Bah


Reged: 02/11/07

Loc: Nevada
Re: ES 25mm 100 AFOV Shipped new [Re: Jobryant]
      #5643357 - 01/25/13 09:03 PM

I will defer that opinion until I have a chance to try them both out in the Obsession 20F5. That would give me a better idea of how it works in a faster scope. When I was trying identify smaller galaxies the additional magnification with the ES 25 was apparent. I didn't have a chance to look a extremely wide objects such as the North America or Veil nebula.

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faackanders2
Carpal Tunnel


Reged: 03/28/11

Re: ES 25mm 100 AFOV Shipped new [Re: JMW]
      #5644290 - 01/26/13 12:08 PM

Quote:

I will defer that opinion until I have a chance to try them both out in the Obsession 20F5. That would give me a better idea of how it works in a faster scope. When I was trying identify smaller galaxies the additional magnification with the ES 25 was apparent. I didn't have a chance to look a extremely wide objects such as the North America or Veil nebula.




Thanks for the visual report. I also have 20mm 100AFOV and 30mm 82AFOV eyepieces, and would like to have your opion on the new 25 100AFOV and which you would use more. I would antipate (me) using the 25mm 100 AFOV the most out of the 3 for widest high power view, if I had all three.


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JMW
Pooh-Bah


Reged: 02/11/07

Loc: Nevada
Re: ES 25mm 100 AFOV Shipped new [Re: faackanders2]
      #5644696 - 01/26/13 04:38 PM

I am not trying to decide on which one to keep. For me, the ES 25mm 100 AFOV is a keeper along with the 21 Ethos and 31T5 Naglar. I think it is finally time to put my T4 Naglars on the market. I really like the 22T4 and 17T4, less so the 12T4. These were my first 3 Televue eyepieces. I just can't fit them all in my case. It is also getting to be a bit heavy. I may buy a Paracorr type II with the proceeds from selling the T4s. Do you think there is any advantage in trying to sell 3 T4s as a set?

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Astrojensen
Post Laureate
*****

Reged: 10/05/08

Loc: Bornholm, Denmark
Re: ES 25mm 100 AFOV Shipped new [Re: JMW]
      #5644757 - 01/26/13 05:12 PM

Quote:

Do you think there is any advantage in trying to sell 3 T4s as a set?




Very likely not. You almost have to sell the set at a somewhat lower price than if you sell them individually, since nearly all people aren't interested in all three focal lengths, but only one of them, maybe two. If there's someone out there looking for them all, he will contact you anyway and you might be able to make him a better deal, since you will only have to send one package, instead of three, thereby cutting your expenses and trouble.

But I think you'll be able to sell them much faster, if you sell them individually.


Clear skies!
Thomas, Denmark


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plav1959
sage
*****

Reged: 05/10/07

Loc: Central Florida
Re: ES 25mm 100 AFOV Shipped new [Re: Astrojensen]
      #5644805 - 01/26/13 05:46 PM

You may have an issue selling as a set, but the good news is they should sell very quickly. I put a 22T4 and a 12T4 on AM and they were both sold within a couple of hours. I'll be very interested to hear how the 25 does in your dob, both with and without a type II paracorr.

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MRNUTTY
Carpal Tunnel
*****

Reged: 11/22/11

Loc: Mendon, MA
Re: ES 25mm 100 AFOV Shipped [Re: plav1959]
      #5645006 - 01/26/13 07:49 PM

I got that 24T4 ;-)

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Shneor
scholastic sledgehammer
*****

Reged: 03/01/05

Loc: Northern California
Re: ES 25mm 100 AFOV Shipped new [Re: Starman1]
      #5652871 - 01/30/13 05:55 PM

Quote:

What do you mean when you say field curvature offset coma?
Field curvature slowly defocuses the star images, but they stay round. Coma stretches the star images radially into fan shapes.
Field curvature can defocus coma, too, making the comatic image slightly larger and out of focus, but it doesn't reduce coma. It can only make the appearance of it worse.
So what you say cannot be reconciled.
I notice a slight amount of astigmatism near the edge, and depending on which side of focus you sit, this could appear to reduce the radial width of the comatic star (while stretching it circumferentially). On the other side of focus, it would make it worse.
I got a quick glance at the Perseus Double Cluster with the eyepiece in a Paracorr II, and the star images displayed a trace of astigmatism, but no obvious coma or field curvature. Since the Paracorr corrects the last two, it's not surprising what I saw. Without the Paracorr, it displayed the normal amount of coma for an f/5 scope and a 100 degree field, i.e. a lot.
However, if the eyepiece actually corrected coma, it would display coma in the Paracorr, and it did not.
Once again, current eyepieces do not correct for coma. If they did, they'd only be useful in short f/ratio newtonians.

Edit:
It just dawned on me that what you are calling field curvature is actually rectilinear distortion (wherein straight lines appear curved near the edge of the field, so ||| becomes )|( in the eyepiece.
Yes, the eyepiece has a lot of that, as do other 100 degree eyepieces.
The correction of RD is impossible in a widefield eyepiece without leaving in tons of Angular Magnification Distortion (AMD), which is considered to be the more deleterious form of distortion in astronomical viewing.
RD is more noticeable when panning quickly, but usually doesn't bother most observers.
AMD, on the other hand, distorts images terribly, so most modern designers opt for RD over AMD.

Field curvature is when the focal plane is curved toward or away from the eye at the edge and it results in out of focus stars. I don't think that was what you were talking about.



Hi Don,
Sorry to take so long to respond, the flu laid me low for almost a couple of weeks, and I lost interest in almost everything.

I think you are correct in describing the distortion. I don't claim it was planned, but in an area roughly 60-90% of the radius, coma seemed to be less than it ought to be.
If the weather cooperates, I'll check it out again this weekend. Last time, I neglected to change to my observing contact lenses, and that may also have affected the view. The distortion was obvious when panning, however.

Clears,


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: ES 25mm 100 AFOV Shipped new [Re: Shneor]
      #5652911 - 01/30/13 06:11 PM

Quote:

I am not trying to decide on which one to keep. For me, the ES 25mm 100 AFOV is a keeper along with the 21 Ethos and 31T5 Naglar. I think it is finally time to put my T4 Naglars on the market. I really like the 22T4 and 17T4, less so the 12T4. These were my first 3 Televue eyepieces. I just can't fit them all in my case. It is also getting to be a bit heavy. I may buy a Paracorr type II with the proceeds from selling the T4s. Do you think there is any advantage in trying to sell 3 T4s as a set?

--------------------
Jeff




Jeff,

Why would you keep all three considering they are all so close in focal length?


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JMW
Pooh-Bah


Reged: 02/11/07

Loc: Nevada
Re: ES 25mm 100 AFOV Shipped new [Re: Scanning4Comets]
      #5653229 - 01/30/13 09:18 PM

I almost always take two scopes to view at dark sites. Sometimes I will also set up a C11 EdgeHD along with the dob and refractor. Most of my viewing is with my 17mm or longer eyepieces. I only go shorter to look at planets or planetary nebula. There is a big difference from the 21 Ethos and Nagler 31T5 so I don't think they are redundant. It will take a summer of viewing before I would make any decision regarding pruning any eyepieces other than my T4 Naglers. I have a Pelican 1550 case and store my eyepieces standing up so I do have a lot of room.

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Jobryant
sage


Reged: 01/13/09

Re: ES 25mm 100 AFOV Shipped new [Re: JMW]
      #5716281 - 03/06/13 12:18 PM

Well I couldn't resist and I had to order me one of these ES25100s. I placed my order from Atronomics on March 1st and received it in the mail yesterday March 5th.

First thing is I really like the cool box the EP came in it's awesome. Unfortunately while I was admiring mine I noticed it was damaged a bit. Normally I wouldn't care too much about the condition of the box but with such a nice looking box like this one I must admit I was pretty bummed when I found the flaw.

The main reason for acquiring this EP is to see if I could use it for my daytime viewings. The allure of viewing with a 25mm 100 degree EP during the day was too much for me to resist even after reading all the early reports suggesting it will probably not work very well for terrestrial viewing. I'll be comparing it against my current daytime champ the 30mm Leitz. I really like the Leitz so in order for me to keep the 25mm ES it will need to perform very well. Side note all the testing was done during the day.

So far I've only been able to use the new EP for about an hour and my initial gut feeling is that I won't be using the ES25100 as a daytime EP. Reason being is that during this short time I already think that the distortion will more than likely be too great for me to overcome. Normally I can handle distortion very well but the amount in the ES25100 is pushing it for me. I felt that I got a bit light headed after viewing with it so no matter how good the EP is if it makes me sick I won't be using it. Hopefully I will get use to looking through a fishbowl without loosing my lunch.

These first impressions are just that and I'll need more time viewing with the EP before making my final decision. With that being said here are a few other things I noticed so far.

In my 50mm F5.6 and 114mm F5.3 refractors curvature was noticeably present. When focusing on axis I'd say about 80% looked in really sharp and in focus at one time. When focusing more towards the outer 1/3rd of the FOV my eyes of 36 years were able to barely overcome the majority of the curvature and I was able to get sharp focus across the entire FOV. The Leitz was the better EP when it came to curvature. More testing is needed to see if coma is present or not.

I felt the on axis sharpness was great on par with the Leitz which is excellent on axis. Color and contrast looked great but I definitely need more time testing this because I was more concentrating on checking the sharpness of the EP then anything else.

I must say I was pleasantly surprised how comfortable the EP was in regards to eye relief, eye placement and lack of blackouts. All these features came together really well for me. I was able to see the entire 100 degrees without nearly as many blackouts as I initially thought I would experience. Yes I did need to tilt my head a bit to see the edges but it was very naturally feeling and not awkward at all for me to do. Even though eye placement to prevent blackouts was fairly easy for me to obtain and hold I found that there seems to be an eye placement sweet spot that was very hard for my to achieve but once found I noticed a reduction in the color fringing seen around the edges.

So far I prefer to remove the rubber eye guard while viewing. The rubber eye guard does in fact feel soft and comfortable against your skin so that's not a issue. I've never like using the eye guards no matter what EP is the reason for me not using the eye guard.

Well that's about it for now. Overall I feel it's a great EP but like others mentioned before me probably not going to be a favorite for terrestrial viewers.


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Rinaldo
Pooh-Bah


Reged: 06/28/04

Loc: Lawng-eye-lind - New York, USA
Re: ES 25mm 100 AFOV Shipped new [Re: Jobryant]
      #5717156 - 03/06/13 07:54 PM

That box is GREAT!

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star drop
contra contrail
*****

Reged: 02/02/08

Loc: Snow Plop, WNY
Re: ES 25mm 100 AFOV Shipped new [Re: Rinaldo]
      #5718048 - 03/07/13 10:19 AM

The heck with the eyepiece. Let's play with the box?

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DRodrigues
super member


Reged: 08/08/11

Re: ES 25mm 100 AFOV Shipped new [Re: Jobryant]
      #5769419 - 03/31/13 06:13 PM

Quote:


So far I've only been able to use the new EP for about an hour and my initial gut feeling is that I won't be using the ES25100 as a daytime EP. Reason being is that during this short time I already think that the distortion will more than likely be too great for me to overcome. Normally I can handle distortion very well but the amount in the ES25100 is pushing it for me. I felt that I got a bit light headed after viewing with it so no matter how good the EP is if it makes me sick I won't be using it. Hopefully I will get use to looking through a fishbowl without loosing my lunch.




Jobryant, did you got used to this ep for daylight use?
Did you ever used an Ethos 21 or 17, for daylight use? If so, how do you compare those to the ES100 25?
I use an Ethos 17 for my cr-birding http://www.pt-ducks.com/cr-telescopes.htm#Test%20of%2082%C2%BA,%20100%C2%BA%20and%20102%C2%BA%20AFOV%20zooms and love it...


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davidpitre
Post Laureate
*****

Reged: 05/10/05

Loc: Central Texas
Re: ES 25mm 100 AFOV Shipped new [Re: JMW]
      #5769569 - 03/31/13 07:45 PM

Quote:

I will defer that opinion until I have a chance to try them both out in the Obsession 20F5.




I don't know if you know your fully dilated pupil size, but for me the 31 Nagler would not be my choice for a 20" f/5 , as it gives about a 6.5mm exit pupil. This is larger than many older eyes can accommodate. At 5.1mm the ES 25mm seems more useable.


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Fred1
Carpal Tunnel
*****

Reged: 09/19/07

Loc: Somewhere in the Orion Spur
Re: ES 25mm 100 AFOV Shipped new [Re: davidpitre]
      #5770500 - 04/01/13 11:00 AM

Has anyone determined the Paracorr setting for the ES 25mm 100°? I fiddled with it some in a friend's 16" f/4.2 as I haven't had a chance to try it in my own scope, yet. Seemed the C or D setting was getting it close. I think B was best for my ES 9mm 100°. Comments?

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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: ES 25mm 100 AFOV Shipped new [Re: Fred1]
      #5770522 - 04/01/13 11:14 AM

Quote:

Has anyone determined the Paracorr setting for the ES 25mm 100°? I fiddled with it some in a friend's 16" f/4.2 as I haven't had a chance to try it in my own scope, yet. Seemed the C or D setting was getting it close. I think B was best for my ES 9mm 100°. Comments?



You can figure it out easily.
Put in an eyepiece for which you know the correct setting of the Paracorr.
Focus the telescope with the Paracorr set to the correct setting for that eyepiece.
Remove the eyepiece and insert the 25mm.
Focus using the tunable top of the Paracorr, not the focuser knobs.
When the eyepiece is in focus, that is the correct setting of the Paracorr for that eyepiece.
Make a note of it and that will be the setting you select before inserting the 25mm the next time.
You may have to make a tiny focuser adjustment to get perfect focus, but this principle works for all eyepiece that have a proper setting within the range of the Paracorr's tunable top (and 99%+ do).
The only thing required is 1 eyepiece for which you know the correct setting of the Paracorr, and you can determine that by trial and error by using every setting of the Paracorr and focusing then looking at the edge of the field and picking the setting that is best corrected (and it can even be done with the stars slightly out of focus).


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Fred1
Carpal Tunnel
*****

Reged: 09/19/07

Loc: Somewhere in the Orion Spur
Re: ES 25mm 100 AFOV Shipped new [Re: Starman1]
      #5771176 - 04/01/13 04:45 PM

Thanks, Don. That's what I did, but perhaps it's the rectilinear distortion of the EP (plus my own slight astigmatism) that's having me waffle between C and D. I used a 24mm Pan set to D and focused before inserting the ES 25mm. I should be able to spend more time on it Wednesday night when I'm out with my 18".

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