Baader Hyperions in 2" mode

[W0nderste]

Hi,

I have a Baader Hyperion 8mm I bought a while ago, but not really had much chance to use it.

but I also just bought an Evostar 72ED. I intend to get a 2" diagonal, and thought great, I can use the baader hyperion with the 1.25 nose piece removed.

unfortunately I just found out that 1.25 nose piece has optics in it so removing it changes the focal length of the EP in 2" mode.

has anyone used a hyperion with 2" only connector?  What focal length does the 8mm become with front optics removed?

ta

[Ricochet]

I don't think the hyperions are designed to be used like that. If you remove the bottom set of lenses the distortions and aberrations from the eyepiece will most likely be absolutely terrible. What you should do is to get a 2"-1.25" reducer to use in the 2" diagonal so you can use 1.25" eyepieces. If you want to use the Hyperion as 2" you will have to buy an additional 2" extension to screw onto the bottom of the eyepiece so that the 2" section of the barrel is as long or longer than the 1.25" section. 

However, given that the 72ED is quite a small telescope you may want to stick to 1.25" eyepieces for ease of balance. A 24mm 68" eyepiece would give you 3.9° which you may find is actually wide enough. 

[John]

Without the 1.25 inch nose and the optics within it, the Hyperions (except the 24mm I think) become 22.9mm focal length eyepieces but not terribly well corrected ones. As indicated above, the general feeling is that they are best used as 1.25 inch eyepieces.

 

 

 

[johninderby]

Yes have heard they aren’t very nice to use without the 1.25” nosepiece.

[W0nderste]

16 minutes ago, Ricochet said:

I don't think the hyperions are designed to be used like that. If you remove the bottom set of lenses the distortions and aberrations from the eyepiece will most likely be absolutely terrible. What you should do is to get a 2"-1.25" reducer to use in the 2" diagonal so you can use 1.25" eyepieces. If you want to use the Hyperion as 2" you will have to buy an additional 2" extension to screw onto the bottom of the eyepiece so that the 2" section of the barrel is as long or longer than the 1.25" section. 

However, given that the 72ED is quite a small telescope you may want to stick to 1.25" eyepieces for ease of balance. A 24mm 68" eyepiece would give you 3.9° which you may find is actually wide enough. 

Thanks.

dumb question then, but why give the scope a 2" connector if you are better with 1.25 diagonal and 1.25 EPs

[W0nderste]

11 minutes ago, John said:

Without the 1.25 inch nose and the optics within it, the Hyperions (except the 24mm I think) become 22.9mm focal length eyepieces but not terribly well corrected ones. As indicated above, the general feeling is that they are best used as 1.25 inch eyepieces.

 

 

 

 

7 minutes ago, johninderby said:

Yes have heard they aren’t very nice to use without the 1.25” nosepiece.

thanks for the info

Hmm, why bother with the 2" functionality then if they are not practical to use 🤔

[John]

2 inch eyepieces can show much larger true fields than 1.25 inch eyepieces of the same focal length.

With the 72ED though I wonder if the 2 inch focuser is mainly aimed at imagers ?

Baader likes to give lots of options for use with their gear. Generally these options work well but with the Hyperion 1.25 inch eyepieces removing the lower optic assembly leaves an optical set based on the Erfle eyepiece design which can work well with a slow scope (eg: F/10, F/12 etc) but struggle with edge correction in faster scopes, such as the ED72 at F/5.8.

As you have the 8mm Hyperion, if you can get hold of a 2 inch diagonal, why not try it and see for yourself ?

 

[Ricochet]

8 hours ago, W0nderste said:

Thanks.

dumb question then, but why give the scope a 2" connector if you are better with 1.25 diagonal and 1.25 EPs

The 2" barrel allows someone with a 2" eyepiece clamp to put the eyepiece straight into the 2" clamp without using a reducer, but you do not remove the 1.25" section of the eyepiece to do this. 

The problem with this approach is that the 1.25" section protrudes a long way below the 2" section and you don't want to damage anything by pushing the eyepiece in too far, for instance the mirror in your diagonal, and so it really only serves newtonians with a good amount of out focus travel. 

 

[scotty38]

I have the 10mm and briefly tried it without the 1.25 section the other night. As I placed it in to my (WO 2") diagonal I could see it was like looking down a tunnel so took it out before even giving it a chance. Maybe I was too hasty so will try again though....