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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. 

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.

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 😊 

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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.

 

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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). 

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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.

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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 ? 

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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 😀

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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

 

 

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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.

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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. 

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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. 

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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. 

FAAB8CBA-6788-4434-B8B7-4F87EE35C2BD.jpeg

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 🥳 

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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

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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.

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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

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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 

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  • 2 months later...
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 :icon_scratch:

"try before you buy" :thumbright:

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