Baader Hyperion 1.25" or 2"?

[Gilps]

I've bought my missus a 2nd hand CPC800 for Xmas, so we've yet to play with it, but I'm pretty excited right now.

As well as the original 1.25" star diagonal and 40mm EP, I also have a William Optics 2" Dielectric Diagonal and 38mm Skywatcher Panaview EP. In addition to the scope, I have also bought her a couple of new EPs which are the 21mm and 13mm Baader Hyperions.

My thoughts are that I will put the original diagonal and EP to one side to gather dust, and just leave the WO diagonal on there all the time as the Panaview can only work in that one, but my question is this, what is the best way to use the Hyperions? Should I keep them as 1.25" and use the adapter in the diagonal, or keep them as 1.25" put in to the 2" fitting hopefully without damaging the prism in the diagonal, or convert them to 2" and use them that way.

From looking on the Baader website it seems that if I unscrew the 1.25" part from the bottom then I will lengthen the FL which seems a bit pointless as I have bought these lengths for a reason.

I'm looking for some advice on the pros and cons of running the Hyperions as 1.25" or 2".

Thanks

[John]

Hyperions are 1.25" eyepieces - personally I'd use them that way with a 1.25" - 2" adaptor in the WO diagonal. With the lower lens set (in the 1.25" barrel) removed they become 22mm (or something like that). If you want to vary their focal length the Fine Tuning Rings work pretty well but are a bit fiddly to use in the dark and you could get dust / dirt inside the eyepiece.

[gustavo_sanchez]

I use my 10mm Hyperion directly on my 2" diagonal and it does not hit the prism. The eyepiece literature states that you should not do that if you add the fine tuning rings, since it will lengthen the eyepiece too much and then it will hit the prism.

[Nexus 6]

Wow! buying a scope for the missus for Chrismas, I might try that then. I could look after it for her. LOL

Alan

[Gilps]

Just thought I would give you an update on this. We had been using the Baader EP's in the 2" diagonal without the adaptor, so in effect letting them drop down into the diagonal further than they would if using the 1.25" adaptor. This was just laziness as we often use the 2" 38mm and didn't bother to fit the adaptor. I wondered if this would alter the focal length and magnification of the EP's, or if the EP FL was set and could not be altered by lifting or lowering it to the prism, but had no way to check it as stars looked the same with or without the adaptor. However, when we got to look at something larger, like the Moon, I realised the error of my ways. By using the EP's directly on to the 2" fitting we were in effect lengthening the FL and reducing the magnification.

We fitted the adaptor and now get the full benefit especially when observing the Moon, which we are just blown away by at the moment.

[sixela]

what is the best way to use the Hyperions?

If you have a diagonal and can't insert them deeply, in 1,25" mode. You shouldn't unscrew the 1.25" lower part -- that changes the eyepiece and removes the Smyth lens group(and except for the 21mm leaves you a fairly so-so eyepiece, although to be honest they're actually almost usable in an SCT.)

The '2" mode' is obtained by just leaving the eyepiece as is but inserting them deeper, until the 2" shoulder. But they go in so deeply that you need lots of focuser out-travel that way, and you should check what happens in your diagonal. One of three things: one, they can be fully inserted up to the 2" shoulder and hit nothing, two, they hit a safety stop somewhere and three, the 1.25" part hits the diagonal prism or mirror. Obviously, if the latter happens you shouldn't use them in 2" mode.

If you actually unscrew the 1.25" part with the field doublet you can insert them safely again, in 2" mode, and you have a longer focal length eyepiece. Pretty bad on fast scopes, but perhaps useful in an SCT.

The only advantage of the 2" mode is not having to bother with a 2"-1.25" adapter if your other eyepieces are all 2" eyepieces. They're really 1.25" eyepieces and the 2" barrel is just there for reasons of convenience mainly for Newt users (who can insert these deeply, even though some need 2" extensions anyway in 2" mode and so may also prefer 1.25" mode).

[sixela]

By using the EP's directly on to the 2" fitting we were in effect lengthening the FL and reducing the magnification.

No, that is not true, unless you actually remove the lower lens group. What does happen is that if you have a scope with moveable mirror, having to move the focal plane inward with the scope focuser to meet the lower position of the eyepiece focal plane will change the SCT effective focal length slightly.

[red dwalf]

you want to view the moon when its no more than half lit then it`s stunning !

all the shadows and creaters are very visable, at the moment it`s too bright and all the detail gets washed out, also get a moon filter to help reduce the brightness,

lovely scope by the way and i think the hyperions work well with the longer focal length scopes

[Nexus 6]

Hi Gilps, nice to see you have been out using the 800, ye you were being lazy not fitting the 1.25 adaptor into the diagonal

As has been said, look out for the Moon if you get the chance over the next week, its really a tremendous sight!

Alan

[Gilps]

We did try it without the moon filter initially. Blimey, that was bright. Then we fitted the Meade ND filter and everything was good.

[Nexus 6]

We did try it without the moon filter initially. Blimey, that was bright. Then we fitted the Meade ND filter and everything was good.

:)

Alan