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Baader Hyperion HYP-31 AND HYP 36 EYEPIECES.

eyepieces
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#1 ras

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Posted 07 November 2019 - 04:11 PM

I am trying to avoid the expense of switching the 1.25" diagonal on my Celestron Evolution 8 to a 2" diagonal so I can use a low power  eyepiece with a 70 degree or better AFOV. for deep sky observing.  The other day I ran across Baader's Hyperion 31mm and 36mm eyepieces which offer a 72 degree AFOV and can be used on either 1.25" or 2" diagonals.  I talked to a tech at Highpoint Scientific who assured me that the field of view would be the same for either size diagonal.  This sounds like the solution to my problem.  Has anyone had any experience using either of these eyepieces. with a 1.25" diagonal?



#2 Mitrovarr

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Posted 07 November 2019 - 04:26 PM

You can't cheat the field stop. If you get an eyepiece that has a wider TFOV than a 32mm plossl or 24mm 68 degree eyepiece, the edge of field illumination will suffer. No way around it.

You'll just have to get a 2" diagonal or a focal reducer if you want fields larger than those available in a 32mm plossl or 24mm 68 degree.
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#3 Viktorious

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Posted 07 November 2019 - 07:34 PM

The technical data sheet from Baader states a 55° AFOV for the 31mm and a 50° AFOV for the 36mm when they are used with the 1.25" barrels.

Screenshot_20191108-015634_Adobe Acrobat.jpg


Edited by Viktorious, 07 November 2019 - 08:00 PM.

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#4 John Huntley

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Posted 07 November 2019 - 07:39 PM

As above, using the 1.25 inch barrel resticts the apparent field of view to the maximum field stop which can be accomodated by the smaller internal diameter barrel.

 

No "free lunch" I'm afraid.



#5 Starman1

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Posted 07 November 2019 - 10:11 PM

And the use of that 1.25" adapter introduces obtrusive vignetting and a very funky exit pupil experience.
It's my opinion the 1.25" adapter provided with those eyepieces is essentially unusable.
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#6 Scott in NC

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Posted 07 November 2019 - 10:19 PM

I talked to a tech at Highpoint Scientific who assured me that the field of view would be the same for either size diagonal. 

Unfortunately, it sounds like he either misunderstood your question or he was sadly misinformed.  I used to own both of these eyepieces and would never have considered using the 1.25" adapter due to the degree of vignetting that it caused.



#7 SeattleScott

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Posted 07 November 2019 - 11:45 PM

I think the 1.25” adapter is kind of a gimmick, so if you have a 2” diagonal on one scope but you also have, say, a Meade ETX that only takes 1.25” eyepieces, then potentially you could just get one low power eyepiece to use with both scopes. But yeah, I haven’t heard of anyone who really uses it. Easier to buy a 32 Plossl for the 1.25” scopes than mess with taking adapter on and off.

Scott
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#8 Riccardo_italy

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Posted 08 November 2019 - 05:48 AM

In any case, a 31mm 55° is remarkably wide for a 1.25" eyepiece.
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#9 SeattleScott

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Posted 08 November 2019 - 06:37 AM

Yes, that would put it on par with say a 35 Ultima.

Scott

#10 Starman1

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Posted 08 November 2019 - 10:17 AM

In any case, a 31mm 55° is remarkably wide for a 1.25" eyepiece.

Well, the apparent field will be heavily vignetted, and it depends how much vignetting you can tolerate

as to how large you feel the apparent field really is. A 55° field will be vignetted in 1.25" at 31mm.


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#11 ras

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Posted 08 November 2019 - 10:29 AM

Thanks for all your replies.  When it sounds too good to be true, it usually is.  


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#12 Starman1

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Posted 08 November 2019 - 12:33 PM

If you want to see the effects of using a 2" eyepiece in a 1.25" focuser, get one of these and try it:

https://agenaastro.c...ce-adapter.html

And you will see why trying to use a 2" eyepiece in a 1.25" holder is not a good idea.


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#13 junomike

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Posted 09 November 2019 - 09:00 AM

If you want to see the effects of using a 2" eyepiece in a 1.25" focuser, get one of these and try it:

https://agenaastro.c...ce-adapter.html

And you will see why trying to use a 2" eyepiece in a 1.25" holder is not a good idea.

It should be called a "Bottleneck Adapter".



#14 cimar

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Posted 09 November 2019 - 10:42 AM

The 31mm Aspheric is a great 2" Eyepiece - I use it for low power observation and star hopping at my dobsonian - but I don't like it as an 1.25" Eyepiece due to vignetting and weird exit pupil.


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#15 F.Meiresonne

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Posted 09 November 2019 - 11:04 AM

i looked the specs up. I cannot understand why they provide an 1.25 inch adapter...which is useless considering the specs of the eyepiece itself...

That adapter seems a hars compromise...


Edited by F.Meiresonne, 09 November 2019 - 11:05 AM.


#16 Jon Isaacs

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Posted 09 November 2019 - 10:45 PM

The 31mm Aspheric is a great 2" Eyepiece - I use it for low power observation and star hopping at my dobsonian - but I don't like it as an 1.25" Eyepiece due to vignetting and weird exit pupil.

 

I have had a friends 31 mm Baader Aspheric for the past two months. I've used it a number of times in my Dobs and the NP-101. To my eye, there's a lot of off-axis astigmatism.

 

Jon



#17 SeattleScott

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Posted 09 November 2019 - 11:34 PM

Well I had a Meade Series 5000 26mm Super Plossl that I liked with my F4 Schmidt-Newtonian. Until I got an ES 24/82 and realized how bad the Meade was (at F4). Just depends on what you are used to!

Interestingly the 5.5mm does much better, but then it is a different design from the rest of the series.

Scott

#18 Highburymark

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Posted 10 November 2019 - 08:29 AM

I use the 36mm with the 1.25” adapter and a PVS-14 monocular for night vision - admittedly not what the eyepiece was designed for. Even then, the edges display astigmatism. Wouldn’t recommend it for a fast telescope.
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