Telescope Reviews: How's this dream team?

The 26T5 is a great alternative to the 31T5. I have them both, and used both last night from my suburban Raleigh observing spot in my driveway.

1) The ONLY practical issue the "too-large" exit pupil of the 31T5 creates is that if you often observe from light-pollution affected suburban skies, the sky background can seem only slightly darker than naked-eye, reducing contrast. That's it, period. Nevertheless, because the primary purpose of the 31T5 in your collection is to serve as a low-power widefield eyepiece, the issue that a too-large exit pupil supposedly "wastes" some light and aperture is completely irrelevant in practice. Also, 31mm is a short-enough focal length that it does not cause secondary shadowing or other vignetting in the overwhelming majority of scopes (among the reasons Nagler probably chose that for the uber-Terminagler's focal length). The weight issue (2.2lbs) of the 31T5 can, however pose significant balancing issues in many scopes, unless you have means to counterbalance it (sliding the dovetail forward in the mount, easily mountable/removable counterweights toward the bottom of a dob, etc).

2) The 26T5 DOES provide a noticeably darker, more contrasty background under suburban light-polluted skies, and provides an impressively immersive "spacewalk" widefield view that only suffers in comparison if you've freshly swapped out a 31T5 from the focuser under dark skies. Let's put it this way - after I got a 31T5, I saw NO reason whatever to get rid of my 26T5, which has repeatedly proven worth its keep. Don't get me wrong - in situations that allow the 31T5 to strut its stuff, I'll usually choose to bring out the 31 (most amazing widefield on the planet IMHO), but the 26 is also superb, and will keep you quite happy with fewer situations where there are useage issues.

As to the Powermate issue, I'm getting along just great with a 2x Powermate coupled with my 13E and 8E with my 12" f/4.9 dob and 90mm APO refractors; the impact of the Powermate is virtually seamless and invisible with both eyepieces - you get literal division of the focal-length in half to 6.5 and 4mm with no impact on eye relief, field of view (vignetting) visible dimunition of light (from other than shortening focal length) etc. MAGNIFICENT views of Jupiter with the powermate + either 13 or 8 Ethos. though 4mm is short enough that in my dob, I'm bumping up against seeing limits many nights, but still a worthwhile view.

Also, you won't miss all that much not having any focal lengths between 31 or 26mm and the 13Ethos. I've kept my 17T4 Nagler, but I wouldn't have purchased it had I obtained the 13E first.

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Chris M., aka "First Sight"
Orion XT12i Dob with Moonlite CR-2 focuser
WO Megrez 90 refractor on UniStar Light mount
Nikon 10x50 Binoculars