Ken82 Posted October 9, 2020 Share Posted October 9, 2020 I decided to upgrade my eyepieces from 82 to 100 degree. The first one arrived this week 😀 Ill need a coma corrector for my dob though. 7 1 Link to comment Share on other sites More sharing options...
John Posted October 9, 2020 Share Posted October 9, 2020 A good start down the 100 degree road ! What focal ratio is your dob ? My 12 inch is F/5.3 but I don't find a CC necessary at that focal ratio with my Ethos's. Link to comment Share on other sites More sharing options...
Paul73 Posted October 9, 2020 Share Posted October 9, 2020 Wonderful eyepieces! I managed without a CC at f4.7. Definitely need one at f4. Although I sold my E21 to pay for the f4 scope. 😁 Enjoy Paul Link to comment Share on other sites More sharing options...
Viktorious Posted October 9, 2020 Share Posted October 9, 2020 Nice! I just sold my 82s as well and have two 100s (20 and 13mm) in shipping to me :). I did however go for the cheaper APM XWA version. We'll see how they do in my f/4.24 (an f/4 with a CC that lives in the focuser). 1 Link to comment Share on other sites More sharing options...
Ships and Stars Posted October 9, 2020 Share Posted October 9, 2020 1 hour ago, Ken82 said: I decided to upgrade my eyepieces from 82 to 100 degree. The first one arrived this week 😀 Ill need a coma corrector for my dob though. You can't go far wrong with the 21E! A beauty. Link to comment Share on other sites More sharing options...
mark81 Posted October 9, 2020 Share Posted October 9, 2020 Fantastic! The only cylinder shaped thing of that size I can look into is my coffee cup! Enjoy... 1 Link to comment Share on other sites More sharing options...
Louis D Posted October 9, 2020 Share Posted October 9, 2020 If you want to do it justice, then you'll just have to get the TV Paracorr T2.😉 If you want to go cheaper on it, then there's the Explore Scientific CC or the GSO/Revelation CC. I have the latter, and it just needs a 25mm extension tube to clean up 95% of the coma at f/5 to f/6. It does need to be removed for high power work because it contributes a bit of spherical aberration that the TVPT2 doesn't. 1 Link to comment Share on other sites More sharing options...
Ken82 Posted October 9, 2020 Author Share Posted October 9, 2020 1 hour ago, John said: A good start down the 100 degree road ! What focal ratio is your dob ? My 12 inch is F/5.3 but I don't find a CC necessary at that focal ratio with my Ethos's. F5 bresser. I did notice quite a bit of coma using my Celestron luminous 31, 23 and baader zoom. I’m not sure if that’s down to collimation or quality of the eyepiece ? Link to comment Share on other sites More sharing options...
Ken82 Posted October 9, 2020 Author Share Posted October 9, 2020 3 minutes ago, Louis D said: If you want to do it justice, then you'll just have to get the TV Paracorr T2.😉 If you want to go cheaper on it, then there's the Explore Scientific CC or the GSO/Revelation CC. I have the latter, and it just needs a 25mm extension tube to clean up 95% of the coma at f/5 to f/6. It does need to be removed for high power work because it contributes a bit of spherical aberration that the TVPT2 doesn't. Yes that’s next on my shopping list along with the legendary 13mm ethos 😀 2 Link to comment Share on other sites More sharing options...
John Posted October 9, 2020 Share Posted October 9, 2020 2 minutes ago, Ken82 said: F5 bresser. I did notice quite a bit of coma using my Celestron luminous 31, 23 and baader zoom. I’m not sure if that’s down to collimation or quality of the eyepiece ? That could be astigmatism from the eyepiece rather than coma from the scope mirror or maybe a mix of both. The Ethos are really well corrected in fast scopes - it's what Tele Vue do excellently. Personally I would try the Ethos 21 for a few sessions and see if you see anything towards the field edges that bothers you. I have the 21, 13, 8 and 6mm Ethos and they are my main set with my 12 inch dob and used without a coma corrector. This useful article shows what the aberrations look like so you might be able to tell them apart: http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html 4 Link to comment Share on other sites More sharing options...
Louis D Posted October 9, 2020 Share Posted October 9, 2020 7 minutes ago, Ken82 said: F5 bresser. I did notice quite a bit of coma using my Celestron luminous 31, 23 and baader zoom. I’m not sure if that’s down to collimation or quality of the eyepiece ? Focus on a star at the edge of the eyepiece and rack focus on either side of that best focus. If the star distorts into a tangential line on one side of best focus and a radial line on the other, that's astigmatism rather than coma you're predominately dealing with. If it looks basically the same on either side like a teardrop fanning out away from the center, that's probably coma. If the star splits into a rainbow radially, that's chromatic aberration. 1 Link to comment Share on other sites More sharing options...
martinl Posted October 9, 2020 Share Posted October 9, 2020 I used this very eyepiece with an f/5 Newtonian and while I could certainly see coma towards the edges it never detracted from the views. I never tried it with a Paracorr, though. People say that once you try a Paracorr you’ll never go back, so I try to avoid trying one. 3 Link to comment Share on other sites More sharing options...
Dantooine Posted October 10, 2020 Share Posted October 10, 2020 7 hours ago, Viktorious said: Nice! I just sold my 82s as well and have two 100s (20 and 13mm) in shipping to me :). I did however go for the cheaper APM XWA version. We'll see how they do in my f/4.24 (an f/4 with a CC that lives in the focuser). Well I’ve just this minute had a go with my APM 20, it’s my only non ethos eyepiece. With my eyes it held its own against the ethos so don’t think you have to lower your expectations by much. A very fine eyepiece. 1 Link to comment Share on other sites More sharing options...
Dantooine Posted October 10, 2020 Share Posted October 10, 2020 (edited) 9 hours ago, Ken82 said: I decided to upgrade my eyepieces from 82 to 100 degree. The first one arrived this week 😀 Ill need a coma corrector for my dob though. Well if that’s the first one things will only get cheaper from now on. It’s the only fl of ethos I wouldn’t stretch to so keep hold of it. Congrats 🥳 Edited October 10, 2020 by Dantooine 3 Link to comment Share on other sites More sharing options...
Sunshine Posted October 10, 2020 Share Posted October 10, 2020 9 hours ago, Ken82 said: Ill need a coma corrector for my dob though. Judging by the size and weight of that hand grenade you'll need a counterweight too! 1 Link to comment Share on other sites More sharing options...
alan potts Posted October 10, 2020 Share Posted October 10, 2020 One of the 100 degree TeleVue's I choose to keep, I did find it needed the paracorr with this though in my F4.3 Dob, I personally don't see the point in paying 800 quid and then settling for coma, the trouble is the parrcorr is another 400. I did see a difference in the TeleVue parrcorr's between the new Mk2 and the old Mk 1 ( I have a feeling there was a model before what I call the Mk 1) The new current model is the only one that gave me perfect results. Great eyepiece though. Alan Link to comment Share on other sites More sharing options...
RickEm Posted October 10, 2020 Share Posted October 10, 2020 Welcome to the club. The 21mm Ethos is a gem. 1 Link to comment Share on other sites More sharing options...
jetstream Posted October 10, 2020 Share Posted October 10, 2020 The 21E is one of the best eyepieces made IMHO. Link to comment Share on other sites More sharing options...
Don Pensack Posted October 10, 2020 Share Posted October 10, 2020 8 hours ago, alan potts said: One of the 100 degree TeleVue's I choose to keep, I did find it needed the Paracorr with this though in my F4.3 Dob, I personally don't see the point in paying 800 quid and then settling for coma, the trouble is the Paracorr is another 400. I did see a difference in the TeleVue Paracorrs between the new Mk2 and the old Mk 1 ( I have a feeling there was a model before what I call the Mk 1) The new current model is the only one that gave me perfect results. Great eyepiece though. Alan The Paracorr II has optimized positions for the 21mm Ethos, the 17mm Ethos and the 31mm Nagler, which the Paracorr I did not. There were at least 3 different versions of the Paracorr I and versions before it. 2 Link to comment Share on other sites More sharing options...
alan potts Posted October 10, 2020 Share Posted October 10, 2020 31 minutes ago, Don Pensack said: The Paracorr II has optimized positions for the 21mm Ethos, the 17mm Ethos and the 31mm Nagler, which the Paracorr I did not. There were at least 3 different versions of the Paracorr I and versions before it. I had both for a while Don, I am not sure which version of Parrcorr 1 I had, the second one I think, it was not as good on Ethos for sure. Alan Link to comment Share on other sites More sharing options...
Ken82 Posted October 10, 2020 Author Share Posted October 10, 2020 It looks patchy cloud tonight so I’ll get it on the dob 😀 I had a play this afternoon with my refractor. Wow love it 😊 4 Link to comment Share on other sites More sharing options...
Ken82 Posted October 12, 2020 Author Share Posted October 12, 2020 I can definitely report the majority of the aberrations I was seeing earlier were from the eyepiece I was using. I could only get glimpses of stars using the dob and ethos but the views were quite spectacular. I’d say that a Paraccor won’t be necessary at this point although I’d like to try it out at some point down the line. Right now I’m going to work out what magnifications I’d like to use and get a set of ethos. Maybe 21, 13, 8 and 6 at first look. Very pleased with this 😀 ken 3 Link to comment Share on other sites More sharing options...
Dantooine Posted December 21, 2020 Share Posted December 21, 2020 On 10/10/2020 at 15:38, jetstream said: The 21E is one of the best eyepieces made IMHO. Shhh I haven’t got a 21 1 2 Link to comment Share on other sites More sharing options...
HollyHound Posted December 21, 2020 Share Posted December 21, 2020 2 hours ago, Dantooine said: Shhh I haven’t got a 21 Yet... 🤣 I certainly have no interest whatsoever in an Ethos of any kind this year either 😬 Link to comment Share on other sites More sharing options...
John Posted December 21, 2020 Share Posted December 21, 2020 Just now, HollyHound said: Yet... 🤣 I certainly have no interest whatsoever in an Ethos of any kind this year either 😬 I'm not sure that they would be your "cup of tea" to be honest with you "try before you buy" 1 Link to comment Share on other sites More sharing options...
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