Help needed with Baader Hyperion 8mm and 17mm

[Jules76 (Julian)]

Hey,

I wondering if someone else with a Hyperion 8mm or 17mm can help me. When using my Baader Hyperions out in the dark with 1.25" filters, I presumed that the front 1.25" section was all the same and was interchanging them instead of unscrewing the filter on and off. I just realised today to my shock after looking at them together for the first time (I brought them seperately) that they aren't the same! One has a large lens opening on the end, the other very small. I tried finding pictures on the web but they weren't much help.

Can anyone with either of these eyepieces tell which one is suppose to be on which? **sheepish grin**

Thanks

[GeoffW1 (Geoff)]

Originally Posted by Jules76

Hey,

I wondering if someone else with a Hyperion 8mm or 17mm can help me. When using my Baader Hyperions out in the dark with 1.25" filters, I presumed that the front 1.25" section was all the same and was interchanging them instead of unscrewing the filter on and off. I just realised today to my shock after looking at them together for the first time (I brought them seperately) that they aren't the same! One has a large lens opening on the end, the other very small. I tried finding pictures on the web but they weren't much help.

Can anyone with either of these eyepieces tell which one is suppose to be on which? **sheepish grin**

Thanks

Hi,

I have these 2 EPs also. The smaller of the 2 extension lenses belongs on the 8 mm EP.

Thanks for the alert.

Cheers

[Jules76 (Julian)]

Hi Geoff,

Thank you very much for the prompt reply. I did indeed have them the wrong way around.

All sorted now and lesson learnt.

[citivolus (Ric)]

Try having the 8, 13, 17, and 24 and having to figure out which goes where

Fortunately I never use them in the 1.25 configuration. If I ever sell them, though, I'll have to figure it out again.

[Jules76 (Julian)]

Originally Posted by citivolus

Fortunately I never use them in the 1.25 configuration. If I ever sell them, though, I'll have to figure it out again.

You mean you have the front 1.25" element detached all the time? How so? I was under the impression that without that front element, it changed the focal length of all the eyepieces to 20mm+.

[citivolus (Ric)]

You seem to have me on that one. I use eyepieces so little these days that I missed it, as I mostly use the 24mm during initial alignment and visual use, and it does not have a lens in this component. I guess I always just assumed that this last element was a parfocalising corrector to compensate for focal length differences when using it as a 2", due to the eyepiece sitting back farther when in the 1.25" configuration.

According to Baader's info:

Each Hyperion eyepiece in the series is actually two eyepieces in one! Simply by unscrewing the forward 1.25-inch diameter portion of barrel that houses the negative achromat lens group, will provide a wide-field eyepiece of much longer focal length. Color correction remains
excellent, and the field curvature that results is no greater than in a decent specimen of the 6-element Erfle design (and that’s what it is actually, when the negative achromat is removed).

[GeoffW1 (Geoff)]

Originally Posted by Jules76

You mean you have the front 1.25" element detached all the time? How so? I was under the impression that without that front element, it changed the focal length of all the eyepieces to 20mm+.

Hi,

Yes, about 22 mm according to this

http://www.alpineastro.com/Hyperion-...s-Version2.pdf

Cheers