Hi, I just noticed this old thread being looked at in the "who's online" pages. I've had some experience with some of the EPs mentioned here.
HYPERIONS- these are a take on the LVWs, but not a clone. These are optimised for SCTs, and with the only exception of the 5mm, are poor performers in Newts. Particularly fast Newts. Like I said, the 5mm is the exception, & it is a cracker in my 8" f/4 Newt!
I had my heart set on Hyperions for a long time, having read many good reviews of them. BUT, what I had missed was the good reviews were all from SCTs & Maks, not Newtonians. It cost me a lot of money this lesson as I bought most of the Hyperion range & found them most distressing to use.
In a strange quirk of things, after a chat with ol' Wavytone about his LVW collection, I came to see why the Hyperions are a poor match to Newt's - they use a Smythe lens as their field lens (except the 5mm & 24mm) which is an optical miss match for the curve of the Newt focal plane. The 24mm is a straight Erfle design, & the 5mm must be using a field lens more akin to a Barlow. One night while using the 13mm Hyperion, it occurred to me to change its Smythe field less for a Barlow - heck! It changed the EP completely, making it a fantastic EP in my fast Newtonians! Curious thing here is it works brilliantly with my cheapie GSO 1.25" 2X Barlow, but nowhere as well with the more 'highly specked' 2" ED 2X Barlow.
Of the 6 Hyperions I've owned, I've kept only the 5mm, & the "Frankenstein" 13mm.
Vixen LVWs - these are excellent performers in ALL scope types, which is just about totally unique in all other EP ranges. I had a good fang of Wavy's LVWs a while ago (thanks again, Wavy
). The 8mm opened my eyes to two aspects of EPs that is next to never mentioned: 1, the ease of use or the lack of eyestrain after long term use - the 8mm is extraordinarily easy to use over an extended period time. 2, variations in performance between EPs in a range. This last point leads me to the last EP review.
Pentax XWs - my experience with these is very limited, I own just the one, the 10mm. In my fast Newts it is excellent, easy to use, very well corrected, & excellent transmission. BUT, for me it is a pig in my C8! There is an optical mismatch here as the eye position goes from very forgiving in my Newts to impossible to manage in the C8. If I can't comfortably look into & use an EP, it doesn't matter any other of its properties - it's unusable, simple as that. Wavy tried it in his Mak one night & loved it. I have to say I agreed with him that it was easier to use in his Mak too. It's just not good in an SCT.
But this does not mean I'm going to right off the entire range of individual XWs. Reading other of the many reviews on XWs shows there is a variation in performance according to the scope design they are used in. Much like the Hyperions. The 14mm is known to be poor in fast Newts, & I think the 30mm too, but they are great in CATs.
I for one am still not sold on my 10mm XW. I can't use it in my C8, which leaves a problematic gap in the useful magnifications at my disposal for the Moon & planets. What is paramount in the EPs in my collection is that they ALL perform well in ALL my scopes. This Pentax is on borrowed time with me.
To finish, if you are considering any EP, do your home work - very few EPs do well in all scope optical designs, including premium lines. Don't just accept a blanket thumbs up for this or that EP, particularly if the recommendation comes from a review that uses a different scope design to the one you will be using it in. I now try to always emphasis the scope along with the EP in question.
Mental
