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Dual Barrel Eyepieces

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#1 bengreen

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Posted 01 August 2020 - 01:13 PM

Hi. I've seen tons of discussion about 1.25" vs 2" eyepieces. But I haven't been able to find anything about dual sized barrels.

The reason I'm asking is that I finally have a decent grab 'n go fast refractor that's been telling me it would be happy with an eyepiece midway between 5mm & 8mm for planetary.

Among the offerings in this range that I've been considering are the Morpheus 6.5mm and Russell 6.7mm Koenig. I do like wide. Both have dual 1.25/2" barrels.

Are there any practical benefits or caveats regarding this barrel design other than the convenience of not having to bother with adapters?

In reality, the Russell choice may be moot. I've been happy with the Koenigs I've bought from Gary but he seems to have a vendetta against his own design, declining to sell the 6.7 - 1.25/2", even though it's been listed as in stock on his web site for years. He said a customer told him it had damaged their diagonal.

Edited by bengreen, 01 August 2020 - 01:23 PM.


#2 Brian Carter

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Posted 01 August 2020 - 01:21 PM

Nope, it is 100% about the convenience of not needing adaptors.

 

i hate adaptors. I hate having to fiddle with anything in the dark, in the middle of the night.  If it’s cold, I hate it even more. A long time ago, bought a bunch of 2” adaptors for my 1.25” eyepieces so I never had to go back and forth again.  One of my better decisions. 


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#3 Starman1

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Posted 01 August 2020 - 02:53 PM

Hi. I've seen tons of discussion about 1.25" vs 2" eyepieces. But I haven't been able to find anything about dual sized barrels.

The reason I'm asking is that I finally have a decent grab 'n go fast refractor that's been telling me it would be happy with an eyepiece midway between 5mm & 8mm for planetary.

Among the offerings in this range that I've been considering are the Morpheus 6.5mm and Russell 6.7mm Koenig. I do like wide. Both have dual 1.25/2" barrels.

Are there any practical benefits or caveats regarding this barrel design other than the convenience of not having to bother with adapters?

In reality, the Russell choice may be moot. I've been happy with the Koenigs I've bought from Gary but he seems to have a vendetta against his own design, declining to sell the 6.7 - 1.25/2", even though it's been listed as in stock on his web site for years. He said a customer told him it had damaged their diagonal.

Careful.  1.25" eyepieces with 2" skirts are still 1.25" eyepieces.

And in a refractor, if used as 2", the 1.25" section can hit the diagonal mirror.

Specifically, Morpheus eyepieces (except the 17.5mm) have their focal planes at the shoulder of the 1.25" section.

The 2" outer is more a convenience for newtonian users, and, even then, the eyepieces will require a LOT of out focus if used as 2".

I use the Morpheus eyepieces exclusively as 1.25" eyepieces in my newtonian so the focal points are not dramatically different than other eyepieces.

Of course, Brian's solution is a good one if you don't want to use a 1.25" adapter--simply convert them all to 2" by attaching adapters to each eyepiece.

It's what I ended up doing with the 17.5 Morpheus to make it parfocal with the others.


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#4 csrlice12

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Posted 01 August 2020 - 04:12 PM

And in a refractor, if used as 2", the 1.25" section can hit the diagonal mirror.

 

Ask me how I know....


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#5 bengreen

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Posted 01 August 2020 - 04:15 PM

Thanks. If I get one, I'll be sure and check clearances first.



#6 Chuck2

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Posted 02 August 2020 - 01:07 AM

Simple solution...

 

When using a Baader Morpheus or Mark IV Zoom in a 2" mirror diagonal, use this inexpensive extension tube to ensure the 1-1/4" eyepiece nose does not hit the diagonal mirror...

 

https://agenaastro.c...-extension.html



#7 SeattleScott

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Posted 02 August 2020 - 01:31 AM

Yep definitely check the spacing in daylight first. My LVWs are fine but I won’t be buying a 2” prism anytime soon.

Scott

#8 25585

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Posted 02 August 2020 - 06:50 AM

A benefit of some adapters is they have smooth noses, so if undercuts bother you, they need not with such a 2" adapter.



#9 *skyguy*

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Posted 02 August 2020 - 07:36 AM

The dual barrel16mm Nagler looks pretty ridiculous when it's in the 1.25" focuser on my 5.5" Comet Catcher.  However, it's an amazing eyepiece when matched with the f/3.64 scope. Who cares about looks!

 

Comet_Catcher_Dob.jpg

 

 



#10 Starman1

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Posted 02 August 2020 - 10:31 AM

Simple solution...

 

When using a Baader Morpheus or Mark IV Zoom in a 2" mirror diagonal, use this inexpensive extension tube to ensure the 1-1/4" eyepiece nose does not hit the diagonal mirror...

 

https://agenaastro.c...-extension.html

That would lift the focal plane of the eyepiece quite a distance out and require a lot more in travel of the focuser.

It would essentially lift the 1.25" shoulder out to where it would be if the eyepiece were used in a 1.25" adapter.

I fail to see the advantage over simply using the eyepiece as a 1.25" with a 1.25" adapter.



#11 RickM.

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Posted Yesterday, 06:13 AM

And in a refractor, if used as 2", the 1.25" section can hit the diagonal mirror.

 

Ask me how I know....

How do you know?  grin.gif



#12 Chuck2

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Posted Today, 03:45 AM

Careful.  1.25" eyepieces with 2" skirts are still 1.25" eyepieces.

And in a refractor, if used as 2", the 1.25" section can hit the diagonal mirror.

 

Don,

I was merely offering a solution to your comment above that using a dual barrel type Baader eyepiece in their 2" skirt format may strike the mirror in a 2" diagonal. No worries if you add a simple, short, $26 extension.

https://agenaastro.c...-extension.html

 

That would lift the focal plane of the eyepiece quite a distance out and require a lot more in travel of the focuser.

It would essentially lift the 1.25" shoulder out to where it would be if the eyepiece were used in a 1.25" adapter.

I fail to see the advantage over simply using the eyepiece as a 1.25" with a 1.25" adapter.

Correct, a short extension essentially lifts the eyepiece to where it would be using a 1.25" adapter; however, there are advantages. With a short extension you are able to attach Baader's 2.25x matched barlow and filters without the eyepiece sticking precariously from the 1.25" adaptor. In the 1.25" format the barlow doesn't seat well, the eyepiece sits high, looks ridiculous and is not as robust as using the 2" skirt format. At star parties, people constantly try to "steer" my scope by the grabing the eyepiece. If your scope came with a decent focuser with good travel and a 2" diagonal, why not use the Baader's in their 2" skirts?

 

Just offering user options, for about the same price you can get either a 1.25 adaptor or short extension.



#13 AstroVPK

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Posted Today, 11:10 AM

Nope, it is 100% about the convenience of not needing adaptors.

 

i hate adaptors. I hate having to fiddle with anything in the dark, in the middle of the night.  If it’s cold, I hate it even more. A long time ago, bought a bunch of 2” adaptors for my 1.25” eyepieces so I never had to go back and forth again.  One of my better decisions. 

 

One of the biggest benefits of standardizing to 2" for me has been avoiding two sets of filters. For the price of a few fairly cheap adaptors, I can stay with 2" filters for al my eyepieces.




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