View Full Version here: : Stratus & Hyperion in Ultra wide mode, how they compare to other ultra wides.

18-10-2006, 09:59 AM
This is a conversation Steve and I had, I thought others might have something to add....

Hi Steve!

Thanks for all your help so far!

I have a quick question for you.... As you might know I have purchased a 10" Dob and now I'm keen to get a wide field EP to use for finding objects and getting that "emersed" view.

I liked the view through your Andrews 30mm 80 degree eyepiece however I did find the aberations (I think it was seaguling) quite distracting.

I'm interested in the fact that the Stratus & Hyperion EP's can have their lower elements removed to give a wider and less magnifyed view (as described in this thread (http://www.iceinspace.com.au/forum/showthread.php?t=6558&highlight=stratus+mod) ). I think this could be good for me as I could essentialy have a good 17mm and (with barlow removed) a wider 30mm (although lesser quality) in the one EP.

So my question is... How do you think your 17mm Hyperion (or a 17mm Stratus) with lens removed compares to your Andrews 30mm, in regards to aberations and FOV?

Thanks Steve!


Steve's Reply:

Hi Dave .... good question, and to be honest I have hardly used my Hyperion 17mm in it's "6 element" mode, ie with the bottom 1.25" barrel assembly removed. Keep in mind that while in it's "separated" form it becomes a 2" eyepiece, which is no problem in the GSO dobs as they take 2" ep's just fine! The Baader Hyperions DO unscrew, the Orion Stratus do NOT.

What I can tell you that IF I remove the lower end the 17mm in terms of focal length it becomes something like a 30mm ep (give or take a bit, it's pretty difficult to say, and the manufacturer have not published figures as far as I can see).
I suspect it is still not an 80 degree apparent field of view unit ..... possibly it is still a 68 degree ep, same as before the end is removed, or perhaps it is somewhere in between, again I'd need to do some careful testing to try and prove this either way.

I'll try the comparison between the 2 as soon as I get a chance, sadly I can't make Ron's place this weekend, I may go out Tuesday night instead weather permitting, I have already asked Ron if he would like a visitor again :-)

I DID see 2 interesting things in the new Aust Sky and Telescope mag that arrived in the post today, read my thread posting here, you may find it relevant.

There is of course another option - William, who owns the big timber 25" dob that is often at Ron's place, has an eyepeice that is also 2" barrel 30mm focal length Ultra Wide 80 degree view, so it's the same specs on paper as my Andrews unit, but in a much more expensive brand than my Andrews one. I think he paid something like $350-400 for it, it IS an awesome eyepiece, no seagulling, and provides better contrast (ie black sky appears blacker, whites are whiter, just like washing powder! lol) One day I may seek one of these out, for now I'll settle for my 30mm Andrews UWA, my 8mm Stratus and 17mm Hyperion (and the 2nd hand 13mm Hyperion I am just buying from another member here - can't wait!)

ALL the best, hope to catch up with you again soon!

18-10-2006, 10:52 AM
The half-Stratus is much worse on its own than the 1rpd/Andrews ultra-wide or the GSO Superview. It is pretty much useless at f/5 unless you re-barlow it. If you want to see the ultra-wide field (with the Stratus 13mm) you need to give up the long eye relief. Eye relief becomes < 7mm.

19-10-2006, 01:42 AM
Very interesting Steve ... thanks for that, sounds like you've saved me from wasting time and good dark skies experimenting. I knew there was a good reason I hadn't tried it much before.

I don't suppose Steve you can comment at all on using Stratus / Hyperions in a binoviewer? Anyone else?? Just a thought I had recently in an email conversation with Gary Beal, and now I am having trouble ridding myself of the idea. Trouble is that this IS an expensive idea to experiment with, if only to find it's a dud concept.